| 1. |
- Cai, Yixiao, 1986-
(författare)
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Bio-Nano Interactions : Synthesis, Functionalization and Characterization of Biomaterial Interfaces
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Current strategies for designing biomaterials involve creating materials and interfaces that interact with biomolecules, cells and tissues. This thesis aims to investigate several bioactive surfaces, such as nanocrystalline diamond (NCD), hydroxyapatite (HA) and single crystalline titanium dioxide, in terms of material synthesis, surface functionalization and characterization.Although cochlear implants (CIs) have been proven to be clinically successful, the efficiency of these implants still needs to be improved. A CI typically only has 12-20 electrodes while the ear has approximately 3400 inner hair cells. A type of micro-textured NCD surface that consists of micrometre-sized nail-head-shaped pillars was fabricated. Auditory neurons showed a strong affinity for the surface of the NCD pillars, and the technique could be used for neural guidance and to increase the number of stimulation points, leading to CIs with improved performance.Typical transparent ceramics are fabricated using pressure-assisted sintering techniques. However, the development of a simple energy-efficient production method remains a challenge. A simple approach to fabricating translucent nano-ceramics was developed by controlling the morphology of the starting ceramic particles. Translucent nano-ceramics, including HA and strontium substituted HA, could be produced via a simple filtration process followed by pressure-less sintering. Furthermore, the application of such materials as a window material was investigated. The results show that MC3T3 cells could be observed through the translucent HA ceramic for up to 7 days. The living fluorescent staining confirmed that the MC3T3 cells were visible throughout the culture period.Single crystalline rutile possesses in vitro bioactivity, and the crystalline direction affects HA formation. The HA growth on (001), (100) and (110) faces was investigated in a simulated body fluid in the presence of fibronectin (FN) via two different processes. The HA layers on each face were analysed using different characterization techniques, revealing that the interfacial energies could be altered by the pre-adsorbed FN, which influenced HA formation.In summary, micro textured NCD, and translucent HA and FN functionalized single crystalline rutile, and their interactions with cells and biomimetic HA were studied. The results showed that controlled surface properties are important for enhancing a material’s biological performance.
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| 2. |
- Cai, Yixiao, et al.
(författare)
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Bioderived Calcite as Electrolyte for Solid Oxide Fuel Cells : A Strategy toward Utilization of Waste Shells
- 2017
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 5:11, s. 10387-10395
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Tidskriftsartikel (refereegranskat)abstract
- The excessive consumption of synthesized materials and enhanced environmental protection protocols necessitate the exploitation of desirable functionalities to handle our solid waste. Through a simple calcination and composite strategy, this work envisages the first application of biocalcite derived from the waste of crayfish shells as an electrolyte for solid oxide fuel cells (SOFCs), which demonstrates encouraging performances within a low temperature range of 450-550 degrees C. The single cell device, assembled from calcined waste shells at 600 degrees C (CWS600), enables a peak power density of 166 mW cm(-2) at 550 degrees C, and further renders 330 and 256 mW cm(-2) after compositing with perovskite La0.6Sr0.4Co0.8Fe0.2O3-delta (LSCF) and layer-structured LiNi0.8Co0.15Al0.05O2 (LNCA), respectively. Notably, an oxygen-ion blocking fuel cell is used to confirm the proton-conducting property of CWS600 associated electrolytes. The practical potential of the prepared fuel cells is also validated when the cell voltage of the cell is kept constant value over 10 h during a galvanostatic operation using a CWS600-LSCF electrolyte. These interesting findings may increase the likelihood of transforming our solid municipal waste into electrochemical energy devices, and also importantly, provide an underlying approach for discovering novel electrolytes for low-temperature SOFCs.
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| 3. |
- Cai, Yixiao, et al.
(författare)
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Biomineralization on Single Crystalline Rutile : The Modulated Growth of Hydroxyapatite by Fibronectin in a Simulated Body Fluid
- 2016
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Ingår i: RSC Advances. - 2046-2069. ; 6, s. 35507-35516
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to probe the complex interaction between surface bioactivity and protein adsorption on single crystalline rutile. Our previous studies have shown that single crystalline rutile possessed in vitro bioactivity and the crystalline faces affected the hydroxyapatite (HA) formation. However, upon implantation, a fast adsorption of proteins, from the biological fluids, is intermediated by a water layer towards the biomaterial interface. Thus the effect of protein on the bioactivity must be addressed. In this study, the HA growth dynamics on (001), (100) and (110) faces was investigated in a simulated body fluid with the presence of fibronectin (FN) by two different processes. The surface adhesion of each face before and after FN adsorption, as revealed by direct numerical values, was determined by atomic force microscopy (AFM) based peak force quantitative nanomechanical mapping (PF-QNM) for the first time. The findings suggest the surface energies of FN pre-adsorbed (001), (100) and (110) faces have been enhanced, leading to the subsequent accelerated HA formation. Furthermore, (001) and (100) faces were found to have larger coverage of HA crystals than (110) face at an early stage. In addition, various characterizations were performed to probe the chemical and crystal structures of as-grown biomimetic HA crystals, and in particular, the Ca/P ratio variations at different soaking time points.
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| 4. |
- Cai, Yixiao, et al.
(författare)
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Changes in secondary structure of alpha-synuclein during oligomerization induced by reactive aldehydes
- 2015
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 464:1, s. 336-341
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Tidskriftsartikel (refereegranskat)abstract
- The oxidative stress-related reactive aldehydes 4-hydroxy-2-nonenal (HNE) and 4-oxo-2-nonenal (ONE) have been shown to promote formation of alpha-synuclein oligomers in vitro. However, the changes in secondary structure of alpha-synuclein and the kinetics of the oligomerization process are not known and were the focus of this study. Size exclusion chromatography showed that after 1 h of incubation, HNE induced the formation of an oligomeric alpha-synuclein peak with a molecular weight of about similar to 2000 kDa, which coincided with a decreasing similar to 50 kDa monomeric peak. With prolonged incubation (up to 24 h) the oligomeric peak became the dominating molecular species. In contrast, in the presence of ONE, a similar to 2000 oligomeric peak was exclusively observed after 15 min of incubation and this peak remained constant with prolonged incubation. Western blot analysis of HNE-induced alpha-synuclein oligomers showed the presence of monomers (15 kDa), SDS-resistant low molecular (30-160 kDa) and high molecular weight oligomers (>= 260 kDa), indicating that the oligomers consisted of both covalent and non-covalent protein. In contrast, ONE-induced alpha-synuclein oligomers only migrated as covalent cross-linked high molecular-weight material (>= 300 kDa). Both circular dichroism (CD) and Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy showed that the formation of HNE- and ONE-induced oligomers coincided with a spectral change from random coil to beta-sheet. However, ONE-induced alpha-synuclein oligomers exhibited a slightly higher degree of beta-sheet. Taken together, our results indicate that both HNE and ONE induce a change from random coil to beta-sheet structure that coincides with the formation of alpha-synuclein oligomers; albeit through different kinetic pathways depending on the degree of cross-linking. (C) 2015 Elsevier Inc. All rights reserved.
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| 5. |
- Cai, Yixiao, et al.
(författare)
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Fabrication of translucent nanoceramics via a simple filtration method
- 2015
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 5:121, s. 99848-99855
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Tidskriftsartikel (refereegranskat)abstract
- Generally, particle packing density, grain size and morphology are the important factors that affect the transparency of ceramics. In order to achieve better transparency of ceramics, efforts should be developed to eliminate or minimize light scattering or absorption. Therefore the porosity and size of crystals in a ceramic body should be strictly controlled. Typical transparent ceramics are fabricated by pressure-assisted sintering techniques such as hot isostatic pressing (HIP), spark plasma sintering (SPS), and pressure-less sintering (PLS). However, a simple energy efficient production method remains a challenge. In this study, we describe a simple fabrication process via a facile filtration system that can fabricate translucent hydroxyapatite based ceramics. The translucent pieces yielded from filtration exhibit optical transmittance that was confirmed by UV spectroscopy. Briefly, the morphology and size of ceramic nanoparticles, filtration pressure and filtration time are important parameters to be discussed. Compared with different hydroxyapatite nanoparticles, spherical nanoparticles easily form a densely packed structure, followed by sintered ceramics. When the strontium content in HA increases, the morphology of HA changes from nano-spheres to nano-rods, following a decrease in transparency. A pressure filtration model combining Darcy's law and the Kozeny-Carman relation has been discussed to simulate and explain why the translucent ceramics can be fabricated via such a simple process. This method could be further applied to prepare other translucent functional ceramics by controlling the size and morphology of ceramic particles.
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| 6. |
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| 7. |
- Cai, Yixiao, et al.
(författare)
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Strategy towards independent electrical stimulation from cochlear implants : Guided auditory neuron growth on topographically modified nanocrystalline diamond
- 2016
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Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1742-7061 .- 1878-7568. ; 31, s. 211-220
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Tidskriftsartikel (refereegranskat)abstract
- Cochlear implants (CI) have been used for several decades to treat patients with profound hearing loss. Nevertheless, results vary between individuals, and fine hearing is generally poor due to the lack of discrete neural stimulation from the individual receptor hair cells. A major problem is the deliverance of independent stimulation signals to individual auditory neurons. Fine hearing requires significantly more stimulation contacts with intimate neuron/electrode interphases from ordered axonal re-growth, something current CI technology cannot provide.Here, we demonstrate the potential application of micro-textured nanocrystalline diamond (NCD) surfaces on CI electrode arrays. Such textured NCD surfaces consist of micrometer-sized nail-head-shaped pillars (size 5 5 lm2) made with sequences of micro/nano-fabrication processes, including sputtering, photolithography and plasma etching.The results show that human and murine inner-ear ganglion neurites and, potentially, neural progenitor cells can attach to patterned NCD surfaces without an extracellular matrix coating. Microscopic methods revealed adhesion and neural growth, specifically along the nail-head-shaped NCD pillars in an ordered manner, rather than in non-textured areas. This pattern was established when the inter-NCD pillar distance varied between 4 and 9 lm.The findings demonstrate that regenerating auditory neurons show a strong affinity to the NCD pillars, and the technique could be used for neural guidance and the creation of new neural networks. Together with the NCD’s unique anti-bacterial and electrical properties, patterned NCD surfaces could provide designed neural/electrode interfaces to create independent electrical stimulation signals in CI electrode arrays for the neural population.
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| 8. |
- Cai, Yixiao, et al.
(författare)
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Utilization of Translucent Hydroxyapatite Nano-Ceramics as a Bio-Window Material
- 2016
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Ingår i: Nano Advances. ; 1, s. 45-49
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Tidskriftsartikel (refereegranskat)abstract
- Bioceramic materials are importantlyused in the field ofhard tissue engineering. The direct detection of cell response is almost impossible for mostof bioceramics due to theiropaqueness. Thus,the live tracking of cell behavior cannot be performedon these ceramics. In this study, we proposea strategy thatdirect observation of cell growth through hydroxyapatite (HA)ceramics can be realized by employing a translucent hydroxyapatite (tHA) nano-ceramic. We obtained MC3T3 preosteoblast cells and cultured them in the presence of tHA for up to 7 days. The results show that MC3T3cells were able to be seen through the tHA. In addition, live fluorescent staining confirmed that the MC3T3 cells were viable throughout the culture time period. The findings reveal the as-fabricated tHA nano-ceramics can bepotentialas a bio-window material for cell adhesion and proliferation.
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| 9. |
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| 10. |
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| 11. |
- Li, Zhiyang, et al.
(författare)
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Magnetic carbon nanotube modified S-scheme TiO2-x/g-C3N4/CNFe heterojunction coupled with peroxymonosulfate for effective visible-light-driven photodegradation via enhanced interfacial charge separation
- 2023
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Ingår i: Separation and Purification Technology. - : Elsevier. - 1383-5866 .- 1873-3794. ; 308
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Tidskriftsartikel (refereegranskat)abstract
- To remediate water bodies contaminated with organic micropollutants, recyclable and visible-light-driven coupled photocatalysis-peroxymonosulfate (PMS) activation systems were established by synthesizing magnetic-carbon-nanotubes (CNFe) modified TiO2-x/g-C3N4/CNFe (TCNCNFe) S-scheme heterojunction with oxygen vacancies (O-v) by a simple hydrothermal-calcination approach. The introduction of O-v and CNFe enhances the visible-light-harvesting efficiency and the internal electric field across the heterojunction accompanying favorable energy band bending could effectively migrate the photoexcited electrons along the S-scheme mechanism, thus highly suppressing in situ recombination and improving charge separation. Therefore the TCNCNFe-(30-500)/PMS/Vis system achieved 95.4% removal efficiency of atrazine after 30 min irradiation, meanwhile exhibited excellent recyclability without metal ion leaching due to the unique pod-like nanostructure of CNFe. Moreover, the impacts of certain various reaction variables on pollutant removal were explored to evaluate the practical application potential. Interestingly, the biotoxicity of the treated reaction filtrate was significantly alleviated compared to that of ATZ solution. Furthermore, the exploration of photocatalytic reaction mechanism revealed that the dominant reactive oxidizing species contributed in the following order: h(+) > (OH)-O-center dot > O-center dot(2)- > (SO4-)-S-center dot, and the feasible photodegradation pathway of atrazine was presented based on the determined in-termediates. Hence, this research work holds great promise in ecological environment protection using sustainable solar energy.
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| 12. |
- Liu, Xueqi, et al.
(författare)
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Study on charge transportation in the layer-structured oxide composite of SOFCs
- 2018
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Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 43:28, s. 12773-12781
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Tidskriftsartikel (refereegranskat)abstract
- In the past few years, triple (H+/O2-/e(-)) conducting materials have been regarded as one of the most promising electrode categories for solid oxide fuel cells (SOFCs). In this work, a layer-structured LiNi0.8Co0.15Al0.05O2-delta (LNCA) with triple conduction has been studied. The semiconductor-ionic conductor (SIC) LNCA-SDC composite has been fabricated by compositing the LNCA material with ionic conductor, i.e., samarium doped ceria (SDC). The electrochemical performance of the LNCA-SDC composite was studied by electrochemical impedance spectroscopy, while its electronic conductivity was confirmed by d.c. polarization method. It is found that the ionic conductivity of the composite is higher than the electronic conductivity by several orders of magnitude. The charge carriers and transportation properties of LNCA-SDC were studied using H+ and O2- blocking layer cells respectively. Results prove that the LNCA-SDC composite is a hybrid oxygen ion-proton conducting material. The oxygen ion conduction is dominated at low temperature (425 -500 degrees C), however, it is comparable with H+ conduction at high temperature (550 degrees C). Additionally, the formation of Li2CO3 under fuel cell operation environment was observed and the mechanism of the hybrid conductivity of LNCA-SDC was studied.
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| 13. |
- Liu, Yanyan, et al.
(författare)
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Superionic Conductivity of Sm3+, Pr3+, and Nd3+ Triple-Doped Ceria through Bulk and Surface Two-Step Doping Approach
- 2017
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 9:28, s. 23614-23623
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Tidskriftsartikel (refereegranskat)abstract
- Sufficiently high oxygen ion conductivity of electrolyte is critical for good performance of low-temperature solid oxide fuel cells (LT-SOFCs). Notably, material conductivity, reliability, and manufacturing cost are the major barriers hindering LT-SOFC commercialization. Generally, surface properties control the physical and chemical functionalities of materials. Hereby, we report a Sm3+, Pr3+, and Nd3+ triple-doped ceria, exhibiting the highest ionic conductivity among reported doped-ceria oxides, 0.125 S cm(-1) at 600 degrees C. It was designed using a two-step wet-chemical coprecipitation method to realize a desired doping for Sm3+ at the bulk and Pr3+/Nd3+ at surface domains (abbreviated as PNSDC). The redox couple Pr3+ Pr4+ contributes to the extraordinary ionic conductivity. Moreover, the mechanism for ionic conductivity enhancement is demonstrated. The above findings reveal that a joint bulk and surface doping methodology for ceria is a feasible approach to develop new oxide-ion conductors with high impacts on advanced LT-SOFCs.
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| 14. |
- Lu, Yuzheng, et al.
(författare)
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Progress in Electrolyte-Free Fuel Cells
- 2016
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Ingår i: FRONTIERS IN ENERGY RESEARCH. - : FRONTIERS MEDIA SA. - 2296-598X. ; 4
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Forskningsöversikt (refereegranskat)abstract
- Solid oxide fuel cell (SOFC) represents a clean electrochemical energy conversion technology with characteristics of high conversion efficiency and low emissions. It is one of the most important new energy technologies in the future. However, the manufacture of SOFCs based on the structure of anode/electrolyte/cathode is complicated and time-consuming. Thus, the cost for the entire fabrication and technology is too high to be affordable, and challenges still hinder commercialization. Recently, a novel type of electrolyte-free fuel cell (EFFC) with single component was invented, which could be the potential candidate for the next generation of advanced fuel cells. This paper briefly introduces the EFFC, working principle, performance, and advantages with updated research progress. A number of key R&D issues about EFFCs have been addressed, and future opportunities and challenges are discussed.
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| 15. |
- Malmstrom, Mikael, et al.
(författare)
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Waveguides in polycrystalline diamond for mid-IR sensing
- 2016
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Ingår i: Optical Materials Express. - 2159-3930 .- 2159-3930. ; 6:4, s. 1286-1295
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Tidskriftsartikel (refereegranskat)abstract
- 8 mm long channel waveguides were manufactured in polycrystalline diamond with inductively coupled plasma etching and characterized in terms of mode-profile and propagation loss in the 1.5 - 3.4 mu m spectral region. As proof of principle, the waveguides were evaluated in an evanescent field sensing setup targeting the CH absorption peak of isopropanol at similar to 3.4 mu m, showing good agreement with numerical finite element simulations. (C) 2016 Optical Society of America
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| 16. |
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| 17. |
- Malmström, Mikael, 1982-, et al.
(författare)
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Diamond waveguides for mid-IR sensing
- 2014
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Ingår i: Optics & Photonics in Sweden. ; , s. 1-1
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 18. |
- Russell, Camilla, et al.
(författare)
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Gold Nanowire Based Electrical DNA Detection Using Rolling Circle Amplification
- 2014
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 8:2, s. 1147-1153
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Tidskriftsartikel (refereegranskat)abstract
- We present an electrical sensor that uses rolling circle amplification (RCA) of DNA to stretch across the gap between two electrodes, interact with metal nanoparticle seeds to generate an electrically conductive nanowire, and produce electrical signals upon detection of specific target DNA sequences. RCA is a highly specific molecular detection mechanism based on DNA probe circularization. With this technique, long single-stranded DNA with simple repetitive sequences are produced. Here we show that stretched RCA products can be metalized using silver or gold solutions to form metal wires. Upon metallization, the resistance drops from T Omega to k Omega for silver and to Omega for gold. Metallization is seeded by gold nanoparticles aligned along the single-stranded DNA product through hybridization of functionalized oligonucleotides. We show that combining RCA with electrical DNA detection produces results in readout with very high signal-to-noise ratio, an essential feature for sensitive and specific detection assays. Finally, we demonstrate detection of 10 ng of Escherichia coli genomic DNA using the sensor concept.
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| 19. |
- Wang, Baoyuan, et al.
(författare)
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CoFeZrAl-oxide based composite for advanced solid oxide fuel cells
- 2016
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Ingår i: Electrochemistry communications. - : Elsevier BV. - 1388-2481 .- 1873-1902. ; 73, s. 15-19
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Tidskriftsartikel (refereegranskat)abstract
- A novel CoFeZrAl-oxide (CFZA) consisted of FeAl2O4, Co3O4 and ZrO2 was prepared by an auto ignition process, displaying a typical morphology of nanorods. The corresponding fuel cell was constructed by using CFZA as the ion-conducting membrane, incorporated between two layers of Ni0.8Co0.15Al0.05Li-oxide pasted on nickel foam (Ni-NCAL), which was used as both electrodes and current collectors. The fuel cell presented an open circuit voltage of 1.07 V and maximum power density of 631 mW/cm(2) at 600 degrees C. The reduction of FeAl2O4 to oxygen-deficient FeAl2O4 (delta) under H-2 condition contributed to the ionic conduction, then the ionic conductor FeAl2O4 (-) (delta) composited with insulator ZrO2 to further enhance the ionic conductivity due to composite effect.
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| 20. |
- Wang, Baoyuan, et al.
(författare)
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Fast ionic conduction in semiconductor CeO2-delta electrolyte fuel cells
- 2019
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Ingår i: NPG ASIA MATERIALS. - : Nature Publishing Group. - 1884-4049 .- 1884-4057. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Producing electrolytes with high ionic conductivity has been a critical challenge in the progressive development of solid oxide fuel cells (SOFCs) for practical applications. The conventional methodology uses the ion doping method to develop electrolyte materials, e.g., samarium-doped ceria (SDC) and yttrium-stabilized zirconia (YSZ), but challenges remain. In the present work, we introduce a logical design of non-stoichiometric CeO2-delta based on non-doped ceria with a focus on the surface properties of the particles. The CeO2-delta reached an ionic conductivity of 0.1 S/cm and was used as the electrolyte in a fuel cell, resulting in a remarkable power output of 660 mW/cm(2) at 550 degrees C. Scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy (EELS) clearly clarified that a surface buried layer on the order of a few nanometers was composed of Ce3+ on ceria particles to form a CeO2-delta@CeO2 core-shell heterostructure. The oxygen deficient layer on the surface provided ionic transport pathways. Simultaneously, band energy alignment is proposed to address the short circuiting issue. This work provides a simple and feasible methodology beyond common structural (bulk) doping to produce sufficient ionic conductivity. This work also demonstrates a new approach to progress from material fundamentals to an advanced low-temperature SOFC technology.
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| 21. |
- Wang, Baoyuan, et al.
(författare)
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Photovoltaic properties of LixCo3-xO4/TiO2 heterojunction solar cells with high open-circuit voltage
- 2016
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 157, s. 126-133
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Tidskriftsartikel (refereegranskat)abstract
- All-oxide solar cells are presently attracting extensive research interest due to their excellent stability, low-cost and non-toxicity. However, the band gap of metal oxides is lack of effective optimization and results in poor photovoltaic performance, thus hindering their practical applications. In this work, Co3O4 was investigated for application as a photo-absorber in all-oxide solar cells, and its band gap was optimized by introducing Li dopant into the spinel structure. LixCo3-xO4 nanoparticles, prepared via the hydrothermal method, were homogenously coated onto TiO2 mesoporous films, which were then used to fabricate planar heterojunction TiO2/LixCo3-xO4 solar cells (SCs). The effects of Li-doping on the heterojunction solar cell performance were further investigated. The findings revealed that the incorporation of Li ions into Co3O4 led to a significant enhancement in short-circuit current density (J(sc)). Remarkably, a high open-circuit voltage (V-oc) of 0.70 V was also achieved. Besides, reasons for the enhanced cell performance are the narrower band gap, reduced photogenerated carrier recombination and the more favorable energy band structure as compared with SCs assembled from pure Co3O4.
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| 22. |
- Wang, Baoyuan, et al.
(författare)
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Preparation and characterization of Sm and Ca co-doped ceria-La0.6Sr0.4Co0.2Fe0.8O3-delta semiconductor-ionic composites for electrolyte-layer-free fuel cells
- 2016
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 4:40, s. 15426-15436
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Tidskriftsartikel (refereegranskat)abstract
- A series of Sm and Ca co-doped ceria, i.e. Ca0.04Ce0.96-xSmxO2-delta (x = 0, 0.09, 0.16, and 0.24) (SCDC), were synthesized by a co-precipitation method. Detailed morphology, composition, crystal structure and electrochemical properties of the prepared materials were characterized. The results revealed that Sm and Ca co-doping could enhance the ionic conductivity in comparison with that of single Ca-doped samples. The composition as Ca0.04Ce0.80Sm0.16O2-delta exhibited a highest ionic conductivity of 0.039 S cm(-1) at 600 degrees C in comparison with the rest of the series, and the optimal ionic conductivity can be interpreted by the coupling effect of oxygen vacancies and mismatch between the dopant ionic radius and critical radius. Composite formation between the semiconductor La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF) and the as-prepared SCDC contributed to a remarkable improvement in the ionic conductivity, an unexpectedly high ionic conductivity of 0.188 S cm(-1) was obtained for LSCF-SCDC composites at 600 degrees C, which was four times higher than that of pure SCDC. Using transmission electron microscopy and spectroscopy approaches, we detected an enrichment of oxygen in the LSCF-SCDC interface region and a depletion of oxygen vacancies in LSCF-SCDC and LSCF-LSCF grain boundaries was significantly mitigated, which resulted in the enhancement of ionic conductivity of semiconductor-ionic LSCF-SCDC composites. The electrolyte-layer-free fuel cell (EFFC) fabricated from the LSCF-SCDC semiconductor-ionic membrane demonstrated excellent performances, e.g. 814 mW cm(-2) at 550 degrees C for using the LSCF-Ca0.04Ce0.80Sm0.16O2-delta (SCDC2).
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| 23. |
- Wang, Baoyuan, et al.
(författare)
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Semiconductor-ionic Membrane of LaSrCoFe-oxide-doped Ceria Solid Oxide Fuel Cells
- 2017
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 248, s. 496-504
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Tidskriftsartikel (refereegranskat)abstract
- A novel semiconductor-ionic La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF)-Sm/Ca co-doped CeO2 (SCDC) nanocomposite has been developed as a membrane, which is sandwiched between two layers of Ni0.8Co0.15Al0.05Li-oxide (NCAL) to construct semiconductor-ion membrane fuel cell (SIMFC). Such a device presented an open circuit voltage (OCV) above 1.0 V and maximum power density of 814 mW cm(-2) at 550 degrees C, which is much higher than 0.84 V and 300 mW cm(-2) for the fuel cell using the SCDC membrane. Moreover, the SIMFC has a relatively promising long-term stability, the voltage can maintain at 0.966 V for 60 hours without degradation during the fuel cells operation and the open-circuit voltage (OCV) can return to 1.06 V after long-term fuel cell operation. The introduction of LSCF electronic conductor into the membrane did not cause any short circuit but brought significant enhancement of fuel cell performances. The Schottky junction is proposed to prevent the internal electrons passing thus avoiding the device short circuiting problem.
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| 24. |
- Wang, Guangjun, et al.
(författare)
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Design, fabrication and characterization of a double layer solid oxide fuel cell (DLFC)
- 2016
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 332, s. 8-15
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Tidskriftsartikel (refereegranskat)abstract
- A double layer solid oxide fuel cell (DLSOFC) without using the electrolyte (layer) has been designed by integrating advantages of positive electrode material of lithium ion battery(LiNi0.8Co0.15Al0.05O2) and oxygen-permeable membranes material (trace amount cobalt incorporated terbium doped ceria, TDC + Co) based on the semiconductor physics principle. Instead of using an electrolyte layer, the depletion layer between the anode and cathode served as an electronic insulator to block the electrons but to maintain the electrolyte function for ionic transport. Thus the device with two layers can realize the function of SOFC and at the same time avoids the electronic short circuiting problem. Such novel DLFC showed good performance at low temperatures, for instance, a maximum power density of 230 mWcm(-2) was achieved at 500 degrees C. The working principle of the new device is presented.
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| 25. |
- Xia, Chen, et al.
(författare)
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Electrochemical properties of LaCePr-oxide/K2WO4 composite electrolyte for low-temperature SOFCs
- 2017
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Ingår i: Electrochemistry communications. - : ELSEVIER SCIENCE INC. - 1388-2481 .- 1873-1902. ; 77, s. 44-48
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we introduced tungstate into solid oxide fuel cells (SOFCs) for the first time by using a La/Pr-doped CeO2 (LCP)/K2WO4 composite as the electrolyte, which exhibited remarkably enhanced grain boundary conduction compared to that of single-phase LCP. The composition dependence of the electrical conductivity was investigated. As a result, the composite with 10 wt% K2WO4 was proven to be the optimum ratio, revealing a significantly higher ionic conductivity than LCP, along with a negligible electronic conductivity. The fuel cell using the LCP/K2WO4 electrolyte displayed an encouraging performance of 500 mW cm(-2) at 550 degrees C. These findings indicate that the LCP/K2WO4 composite is a promising electrolyte for low-temperature SOFCs.
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| 26. |
- Xia, Chen, et al.
(författare)
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Industrial-grade rare-earth and perovskite oxide for high-performance electrolyte layer-free fuel cell
- 2016
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Ingår i: Journal of Power Sources. - : Elsevier. - 0378-7753 .- 1873-2755. ; 307, s. 270-279
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, we report a composite of industrial-grade material LaCePr-oxide (LCP) and perovskite La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) for advanced electrolyte layer-free fuel cells (EFFCs). The microstructure, morphology, and electrical properties of the LCP, LSCF, and LCP-LSCF composite were investigated and characterized by XRD, SEM, EDS, TEM, and EIS. Various ratios of LCP to LSCF in the composite were modulated to achieve balanced ionic and electronic conductivities. Fuel cell with an optimum ratio of 60 wt% LCP to 40 wt% LSCF reached the highest open circuit voltage (OCV) at 1.01 V and a maximum power density of 745 mW cm-2 at 575°C, also displaying a good performance stability. The high performance is attributed to the interfacial mechanisms and electrode catalytic effects. The findings from the present study promote industrial-grade rare-earth oxide as a promising new material for innovative low temperature solid oxide fuel cell (LTSOFC) technology.
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| 27. |
- Xia, Chen, et al.
(författare)
-
Natural Mineral-Based Solid Oxide Fuel Cell with Heterogeneous Nanocomposite Derived from Hematite and Rare-Earth Minerals
- 2016
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 8:32, s. 20748-20755
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Tidskriftsartikel (refereegranskat)abstract
- Solid oxide fuel cells (SOFCs) have attracted much attention worldwide because of their potential for providing clean and reliable electric power. However, their commercialization is subject to the high operating temperatures and costs. To make SOFCs more competitive, here we report a novel and attractive nanocomposite hematite LaCePrOx (hematite LCP) synthesized from low-cost natural hematite and LaCePr-carbonate mineral as an electrolyte candidate. This heterogeneous composite exhibits a conductivity as high as 0.116 S cm(-1) at 600 degrees C with an activation energy of 0.50 eV at 400-600 degrees C. For the first time, a fuel cell using such a natural mineral-based composite demonstrates a maximum power density of 625 mW cm(-2) at 600 degrees C and notable power output of 386 mW cm(-2) at 450 degrees C. The extraordinary ionic conductivity and device performances are primarily attributed to the heterophasic interfacial conduction effect of the hematite-LCP composite. These superior properties, along with the merits of ultralow cost, abundant storage, and eco-friendliness, make the new composite a highly promising material for commercial SOFCs.
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| 28. |
- Xia, Chen, et al.
(författare)
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Semiconductor electrolyte for low-operating-temperature solid oxide fuel cell : Li-doped ZnO
- 2018
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Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 43:28, s. 12825-12834
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Tidskriftsartikel (refereegranskat)abstract
- Semiconductors have been successfully demonstrated as the electrolytes for solid oxide fuel cells (SOFCs) in recent years. Many such semiconductors have shown their potentials as a competent ionic conductor for fuel cell operation, indicated by the appreciable ionic conduction and electrochemical performance. In the present study, we depart from traditional electrolyte concept to introduce a new semiconductor electrolyte, Li-doped ZnO to low-operating-temperature SOFCs. The used material was synthesized via a co-precipitation method and investigated from phase structure, morphology and UV-vis absorption perspectives. Utilizing Li-doped ZnO as electrolyte layer, we found the corresponding fuel cell exhibited a remarkable maximum power density of 443 mW cm(-2) along with open circuit voltage (OCV) of 1.07 V at 550 degrees C, and represented a lower-temperature operation feasibility with power outputs of 138-165 mW cm(-2) at 425-450 degrees C. Besides, high ionic conductivities of 0.028-0.087 S cm(-1) and low activation energy of 0.5 eV were also found in the synthesized Li-doped ZnO at 425-550 degrees C. Our investigation in terms of electrochemical impedance spectra (EIS) analysis manifested that Li-doped ZnO as the electrolyte layer boosted the electrode reactions of the device, which resulted in rather small polarization resistances and eventually realized good low-temperature performances. Further study based on the rectification characteristic of Ni/Li-doped ZnO contact verified the Schottky junction formation of Li-doped ZnO with anodic Ni, which can avoid the underlying electronic short-circuiting problem. These findings show a profound significance of using doped semiconductor for the future exploitation of SOFC electrolytes.
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| 29. |
- Xia, Chen, et al.
(författare)
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Strategy towards cost-effective low-temperature solid oxide fuel cells : A mixed-conductive membrane comprised of natural minerals and perovskite oxide
- 2017
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Ingår i: Journal of Power Sources. - : Elsevier. - 0378-7753 .- 1873-2755. ; 342, s. 779-786
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Tidskriftsartikel (refereegranskat)abstract
- Our previous work has revealed the feasibility of natural hematite as an electrolyte material for solid oxide fuel cells (SOFCs), tailoring SOFCs to be a more economically competitive energy conversion technology. In the present work, with the aim of exploring more practical uses of natural minerals, a novel composite hematite/LaCePrOx-La0.6Sr0.4Co0.2Fe0.8O3-δ (hematite/LCP-LSCF) has been developed from natural hematite ore, rare-earth mineral LaCePr-carbonate, and perovskite oxide LSCF as a functional membrane in SOFCs. The heterogeneity, nanostructure and mixed-conductive property of the composite were investigated. The results showed that the hematite/LCP-30 wt% LSCF composite possessed balanced ionic and electronic conductivities, with an ionic conductivity as high as 0.153 S cm−1 at 600 °C. The as-designed fuel cell using the hematite/LCP-LSCF membrane exhibited encouraging power outputs of 303 – 662 mW cm−2 at 500 – 600 °C. These findings show that the hematite/LCP-LSCF based fuel cell is a viable strategy for developing cost-effective and practical low-temperature SOFCs (LTSOFCs).
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| 30. |
- Zhang, Wei, et al.
(författare)
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Mixed ionic-electronic conductor membrane based fuel cells by incorporating semiconductor Ni0.8Co0.15Al0.05LiO2-delta into the Ce0.8Sm0.2O2-delta-Na2CO3 electrolyte
- 2016
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 41:34, s. 15346-15353
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, a novel composite was fabricated by incorporating the semiconductor Ni0.8Co0.15Al0.05LiO2-delta (NCAL) into the ionic electrolyte Ce0.8Sm0.2O2-delta-Na2CO3 (NSDC), and further developed as a mixed-conducting membrane for single layer fuel cell (SLFC) applications. Experimentally, the crystal structure, morphology, chemical composition and thermo-stability of the composite were characterized by XRD, SEM and TGA. The best cell performance was investigated when the NSDC-NCAL membrane was optimized at a weight ratio of 6:4. On this basis, a number of interesting findings were obtained: i) the mixed conducting membrane did not cause any short circuit; on the contrary, the cell reached a decent open circuit voltage (OCV) of similar to 1.0 V. a high power density of 1072 mW cm(-2) was achieved at 550 degrees C for the NSDC-NCAL membrane based cell, which was much better than that using a pure NSDC electrolyte membrane. Electrochemical impedance spectroscopy (EIS) showed that the NSDC-NCAL composite exhibited significantly improved grain boundary conduction and reduced electrode polarizations, contributing to the resultant performance. To consolidate the usefulness of the device, we also conducted the durability test. The above findings indicate the strategy of introducing mixed NSDC-NCAL membrane is feasible for high-performance SLFCs operating at low temperatures.
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| 31. |
- Zhang, Wei, et al.
(författare)
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The fuel cells studies from ionic electrolyte Ce0.8Sm0.05Ca0.15O2-delta to the mixture layers with semiconductor Ni0.8Co0.15Al0.05LiO2-delta
- 2016
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 41:41, s. 18761-18768
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Tidskriftsartikel (refereegranskat)abstract
- The mixture of ionic electrolyte Ce0.8Sm0.05Ca0.15O2-delta (SCDC) and semiconductor Ni0.8Co0.15Al0.05LiO2-delta (NCAL) layers was used for low temperature solid oxide fuel cell (LT-SOFC) applications. Using the as-prepared SCDC-NCAL semiconductor-ionic layer to replace the ionic SCDC electrolyte, following results have been obtained: the SCDC electrolyte fuel cell reached a lower voltage, 1.05 V, and lower power output, 415 mW cm(-2), compared to that using the semiconductor-ionic layer, 1.06 V and 617 mW cm(-2) at 550 degrees C. The electrochemical impedance spectroscopy (EIS) was applied to investigate the electrochemical processes of the device; X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) for the microstructure and morphology of the as-prepared materials. The results have illuminated that the introduction of semiconductor into ionic electrolyte could make extended triple phase boundary (TPB) area, which can provide more active sites to accelerate the fuel cell reactions and enhance the cell performance. Furthermore, we also discovered that the ionic SCDC and electronic NCAL should be in an appropriate composition to achieve a balanced ionic and electronic conductivity, which is the key issue for high performance semiconductor-ionic fuel cells.
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