| 1. |
- Chen, X. X., et al.
(författare)
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Traditional earth-abundant coal as new energy materials to catalyze the oxygen reduction reaction in alkaline solution
- 2016
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Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686. ; 211, s. 568-575
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Tidskriftsartikel (refereegranskat)abstract
- Coal is an earth-abundant energy resource, however, its direct combustion results in serious environmental pollution. Therefore, it becomes important to design value-added products from coal and to maximize its value chain. Herein, brown coal was used to develop non-precious metal catalysts for the oxygen reduction reaction (ORR) in fuel cells as green energy conversion systems. The brown coal was first pretreated with different acids, followed by N-doping at 800 degrees C in a stream of NH3. A trace amount of Fe was further added to improve the electrocatalytic performance of the prepared catalyst towards ORR. The prepared coal-derived N-doped carbon further modified with 0.5% Fe exhibited onset potential of 0.92 V vs. RHE at a current density of -0.1 mA cm(-2) and a predominantly 4-electron transfer pathway of oxygen to water in 0.1 M NaOH, which was evaluated by RDE and RRDE. The prepared electrocatalysts were further characterized by elemental analysis, XRD, Raman and XPS. The results suggest that the coal-derived ORR catalyst have convoluted graphitic and amorphous carbon structures. The N-content increased after acid-pretreatment and subsequent functionalization with nitrogen, while it slightly decreased after Fe incorporation apparently due to coordination of Fe with N. ORR activity enhancement after the incorporation of Fe is expected to mainly arise from a synergetic effect involving the interaction of Fe with N groups distributed in the carbon matrix. (C) 2016 Elsevier Ltd. All rights reserved.
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| 2. |
- Englund, Johanna, 1988, et al.
(författare)
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Deactivation of a Pd/Pt Bimetallic Oxidation Catalyst Used in a Biogas-Powered Euro VI Heavy-Duty Engine Installation
- 2019
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Ingår i: Catalysts. - : MDPI. - 2073-4344. ; 9:12
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Tidskriftsartikel (refereegranskat)abstract
- The reduction of anthropogenic greenhouse gas emissions is crucial to avoid further warming of the planet. We investigated how effluent gases from a biogas powered Euro VI heavy-duty engine impact the performance of a bimetallic (palladium and platinum) oxidation catalyst. Using synthetic gas mixtures, the oxidation of NO, CO, and CH4 before and after exposure to biogas exhaust for 900 h was studied. The catalyst lost most of its activity for methane oxidation, and the activity loss was most severe for the inlet part of the aged catalyst. Here, a clear sintering of Pt and Pd was observed, and higher concentrations of catalyst poisons such as sulfur and phosphorus were detected. The sintering and poisoning resulted in less available active sites and hence lower activity for methane oxidation.
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| 3. |
- Leistner, Kirsten, 1984, et al.
(författare)
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Ammonia Desorption Peaks Can Be Assigned to Different Copper Sites in Cu/SSZ-13
- 2017
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Ingår i: Catalysis Letters. - : Springer Science and Business Media LLC. - 1572-879X .- 1011-372X. ; 147:8, s. 1882-1890
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study is to attribute NH 3 -TPD peaks observed over Cu/SSZ-13 catalysts to different catalytic sites. This is done by comparing a large number of copper loadings, especially below 40% ion exchange, to be able to see effects relevant to sites in both 6-membered and 8-membered rings. We found that intermediate (200–300 °C) and high (400–500 °C) temperature NH 3 -TPD peaks followed similar trends to the copper species in 6-membered and 8-membered rings respectively, as seen by H 2 -TPR and NO-DRIFTS. Thus we propose that these two TPD peaks represent ammonia stored on H and Cu sites in 6 and 8-membered rings, respectively. This assignment is further supported by the finding that the intermediate and high temperature NH 3 -TPD peaks of samples with different Si/Al ratios also follow the same trend. Moreover, we observe that the activation energy for ammonia oxidation is significantly lower for Cu in 6MR compared to Cu in 8MR rings. Graphical Abstract: [Figure not available: see fulltext.].
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| 4. |
- Pan, Haoran, et al.
(författare)
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Microwave-Assisted Synthesis of Co/CoOx Supported on Earth-Abundant Coal-Derived Carbon for Electrocatalysis of Oxygen Evolution
- 2019
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 1945-7111 .- 0013-4651. ; 166:8, s. F479-F486
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Tidskriftsartikel (refereegranskat)abstract
- The evident demand for hydrogen as the ultimate energy fuel for posterity calls for the development of low-cost, efficient and stable electrocatalysts for water splitting. Herein, we report the synthesis of Co/CoOx supported on coal-derived N-doped carbon via a simple microwave-assisted method and demonstrate its application as an efficient catalyst for the oxygen evolution reaction (OER). With the optimal amount of cobalt introduced into the N-doped coal-derived, the developed catalyst achieved overpotentials of 0.370 and 0.429 V during water oxidation at current densities of 1 mA cm(-2) and 10 mA cm(-2), respectively. There was no noticeable loss in the activity of the catalyst during continuous galvanostatic polarization at a current density of 10 mA cm(-2) for a test period of 66 h. The synergistic interaction of the Co/CoOx moieties with the pyridinic and pyrollic nitrogen functional groups in the N-doped carbon, as well with the other heteroatoms species in the pristine coal favored enhancement of the OER electrocatalytic performance. (C) The Author(s) 2019. Published by ECS.
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| 5. |
- Safo, Isaac Adjei, et al.
(författare)
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Oxidation and stability of multi-walled carbon nanotubes in hydrogen peroxide solution
- 2018
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Ingår i: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584. ; 214, s. 472-481
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation and stability of multi-walled carbon nanotubes (CNTs) have been investigated by exposing CNTs in 30% w/v H2O2 solution at room temperature (RT) for up to 8 weeks and at 80 degrees C for up to 8 h. H2O2 oxidation not only generated surface oxygen-containing groups, but also created surface defects, as disclosed by results of temperature-programmed desorption and X-ray Photoelectron Spectroscopy. The total surface oxygen content was found to be correlated to the final H2O2 concentration. The higher the total surface oxygen content on CNTs, the lower the final H2O2 concentration. Meanwhile, the carbon oxidation and simultaneous H2O2 decomposition were observed and confirmed by an online analysis of evolved gases during the oxidation stepwise heated from room temperature to 80 degrees C. Raman study showed that the DIG and D'/G ratios of the CNTs oxidized at RT first decreased with an oxidation time of 4 weeks and then increased when prolonging the oxidation time up to 8 weeks. Similar trend was also observed on the CNTs oxidized at 80 degrees C. The size of CNTs was gradually reduced with increasing oxidation time as shown by SEM studies. Our work reveals the critical changes in the surface oxygen groups as well as the changes in morphology at two distinct stages of hydrogen peroxide treatment, purification and then functionalization. CNTs can withstand 30% w/v H2O2 oxidation for only a certain time, while they may be damaged or consumed eventually in long-term applications. Our study contributes to filling in the knowledge gap about CNT surface oxidation and structural changes with H2O2 treatment under industrial conditions.
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| 6. |
- Wang, Aiyong, 1989, et al.
(författare)
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A deactivation mechanism study of phosphorus-poisoned diesel oxidation catalysts: Model and supplier catalysts
- 2020
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Ingår i: Catalysis Science and Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 10:16, s. 5602-5617
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Tidskriftsartikel (refereegranskat)abstract
- The effect of phosphorus poisoning on the catalytic behavior of diesel oxidation catalysts was investigated over model and supplier monolith catalysts, i.e., Pd-Pt/Al2O3. The results of ICP and XPS from the vapor-phase poisoning over model catalysts suggested that the temperature of phosphorus poisoning affects both the overall content of phosphorus and the dispersion of phosphorus (i.e., inlet/outlet and surface/bulk). Phosphorus oxide (P2O5), metaphosphate (PO3-), and phosphate (PO43-) were identified in the poisoned model and supplier catalysts. The distribution of these species on poisoned model catalysts was highly dependent on the poisoning temperature, i.e., a higher temperature resulted in a higher concentration of PO43-. The outlets of the monoliths contained more PO43- and less P2O5 than the inlets. Both active sites and surface OH groups on model and supplier catalysts were contaminated upon phosphorus poisoning. It is found that PO43- had a stronger influence on the active sites than P2O5. One significant finding in this study is that the vapor-phase phosphorus poisoning could be a practical and cost efficient approach to simulate an accelerated aging/poisoning process.
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| 7. |
- Wang, Aiyong, 1989, et al.
(författare)
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Deactivation mechanism of Cu active sites in Cu/SSZ-13 — Phosphorus poisoning and the effect of hydrothermal aging
- 2020
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Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 269
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Tidskriftsartikel (refereegranskat)abstract
- Non-poisoned and P-poisoned Cu/SSZ-13 catalysts with different types of Cu sites, i.e., [Cu(OH)]+ and Cu2+, were investigated for NH3-SCR. Phosphorus was found to interact more with [Cu(OH)]+ than Cu2+. Moreover, less phosphorus was required per Cu for poisoning in the samples with a high content of [Cu(OH)]+. We propose a phosphorus poisoning mechanism based on H2-TPR and XPS: poisoning of one Cu2+ involved two P atoms, i.e., P2O5, but for [Cu(OH)]+ contamination, only one P atom (PO3− or PO43−) is needed. Furthermore, phosphorus poisoning resulted in a decline in NH3/NO oxidation and an improvement in SCR activity at high temperatures. Upon hydrothermal aging, [Cu(OH)]+−phosphate/metaphosphate complexes were likely easier detached from the framework than the Cu2+−P2O5 species. This resulted in that the P-poisoned catalyst with high content [Cu(OH)]+ experienced more severe deactivation and dealumination than the non-poisoned catalyst. Additionally, 27Al-NMR suggested that the formation of AlPO4 has a linear relationship with [Cu(OH)]+/Cu2+ ratios.
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| 8. |
- Wang, Aiyong, 1989, et al.
(författare)
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Insight into the effect of phosphorus poisoning of Cu/zeolites with different framework towards NH 3 -SCR
- 2023
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 454
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Tidskriftsartikel (refereegranskat)abstract
- Cu/zeolites were prepared to elucidate the effect of phosphorus poisoning on different zeolite framework structures for NH3-SCR. The results show that there are significant differences in phosphorus poisoning depending on the zeolite framework structure. The PO3−/PO43− species gradually decreased along with an increase in P2O5 in the following order: Cu/SSZ-13, Cu/ZSM-5, and Cu/BEA. One possible reason could be the increased pore size of these zeolites, which results in less steric hindrance for larger P2O5 species. P2O5 is suggested to enhance the redox ability of Cu ions, which results in an increase in low-temperature activity in NH3-SCR, whereas Cu ions were significantly poisoned by PO3−/PO43−, resulting in low-temperature deactivation. Furthermore, the effect of phosphorus poisoning on the structure of Cu/ZSM-5 was found to be much greater than that of Cu/BEA and Cu/SSZ-13, possibly due to phosphorus attacked the surface defects of the zeolite, causing local expansion and cracking.
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| 9. |
- Wang, Aiyong, 1989, et al.
(författare)
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Layered Pd/SSZ-13 with Cu/SSZ-13 as PNA − SCR dual-layer monolith catalyst for NOx abatement
- 2021
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Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 360, s. 356-366
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Tidskriftsartikel (refereegranskat)abstract
- A concept of a layered Pd/SSZ-13 with Cu/SSZ-13 as PNA-SCR dual-layer monolith catalyst for NOx abatement is demonstrated. NO-TPD was employed for determining the NOx storage, and the samples are characterized in detail using SEM-EDX, CO/NO-DRIFTS, XPS and H2-TPR. 750 °C hydrothermal treatment greatly promotes the NOx storage capacity and the addition of CO promotes NOx storage capacity and also shifts the NOx desorption temperature. The dual-layer sample (Pd/SSZ-13+Cu/SSZ-13) maintains most of the NOx storage capacity while the NOx desorption temperature is modified due to Cu/SSZ-13 as the top layer. The layered sample work well for NH3-SCR reaction. Notably, for Pd/SSZ-13+Cu/SSZ-13, more than 80 % of the NOx trapped at low temperature (i.e., 80 °C) can desorb in the suitable SCR temperature region where NOx conversion higher than 80 % is found. However, some loss of NO storage is found after SCR experiments. Overall, the dual-layer concept shows interesting potential for NOx abatement, but requires further developments on the PNA material to ensure stable storage capacity.
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| 10. |
- Wijayanti, Kurnia, 1979, et al.
(författare)
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Effect of gas compositions on SO2 poisoning over Cu/SSZ-13 used for NH3-SCR
- 2017
-
Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 219, s. 142-154
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on the effect of gas composition during SO2 poisoning over Cu/SSZ-13 for NH3-SCR application and was performed by conducting SO2-TPD experiments in a variety of lean gas compositions. In addition, the poisoned monoliths were characterized in detail using ICP-SFMS, UV–vis and XPS. During SO2 poisoning under dry and lean conditions, two different sulfur species were found, which were assigned to weakly bound SO2 and copper sulfate like species. Moreover, a significantly larger amount of copper sulfates was present in humid environment. The presence of NH3 during the poisoning resulted in the formation of ammonium sulfate species which were decomposed at the same temperature independently if the poisoning with SO2 was conducted in ammonia oxidation conditions or under standard or fast SCR conditions. Moreover, if the temperature ramp was conducted with O2 and H2O compared to Ar alone, more stable sulfate species were formed. In addition, SO2 poisoning under standard SCR conditions resulted in mostly ammonium sulfate formation at 200 °C, whereas copper sulfates were predominant after poisoning at 400 °C. After hydrothermal aging at 800 °C, more reducible copper species were noticeable and UV–vis showed that copper oxides had been formed. Sulfur poisoning of the hydrothermally aged sample resulted in the additional formation of copper sulfates during poisoning at 200 °C, which was not the case for poisoning of the fresh catalyst. Thus, the copper oxide species enhanced the copper sulfate formation.
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| 11. |
- Xie, Kunpeng, 1985, et al.
(författare)
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A reevaluation of the correlation between the synthesis parameters and structure and properties of nitrogen-doped carbon nanotubes
- 2015
-
Ingår i: Journal of Energy Chemistry. - : Elsevier BV. - 2095-4956. ; 24:4, s. 407-415
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen-doped carbon nanotubes (NCNTs) were synthesized by chemical vapor deposition using cobalt-based oxides as catalyst and ethylenediamine (EDA) as carbon/nitrogen precursor. The influence of growth time, EDA concentration and growth temperature on the morphology, yield, composition, graphitization and oxidation resistance of the NCNTs was systematically investigated by using Raman spectroscopy, temperature-programmed oxidation and other techniques. The NCNT growth from ethylenediamine with a high N/C ratio involves several processes including mainly (1) catalytic growth of NCNTs, (2) homogeneous gas-phase decomposition of EDA, (3) non-catalytic deposition of pyrolytic carbon/nitrogen species and (4) surface etching of amorphous carbon or carbon at defect sites through gasification. At a later growth stage the etching process appears to be dominating, leading to the thinning of nanotubes and the decrease of yield. Moreover, the surface etching through carbon gasification strongly influences the structure and degree of graphitization of NCNTs.
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| 12. |
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| 13. |
- Xie, Kunpeng, 1985, et al.
(författare)
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Co3O4–MnO2–CNT Hybrids Synthesized by HNO3 Vapor Oxidation of Catalytically Grown CNTs as OER Electrocatalysts
- 2015
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Ingår i: ChemCatChem. - : Wiley. - 1867-3899 .- 1867-3880. ; 7:18, s. 3027-3035
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Tidskriftsartikel (refereegranskat)abstract
- An efficient two-step gas-phase method was developed for the synthesis of Co3O4–MnO2–CNT hybrids used as electrocatalysts in the oxygen evolution reaction (OER). Spinel Co–Mn oxide was used for the catalytic growth of multiwalled carbon nanotubes (CNTs) and the amount of metal species remaining in the CNTs was adjusted by varying the growth time. Gas-phase treatment in HNO3 vapor at 200 °C was performed to 1) open the CNTs, 2) oxidize encapsulated Co nanoparticles to Co3O4 as well as MnO nanoparticles to MnO2, and 3) to create oxygen functional groups on carbon. The hybrid demonstrated excellent OER activity and stability up to 37.5 h under alkaline conditions, with longer exposure to HNO3 vapor up to 72 h beneficial for improved electrocatalytic properties. The excellent OER performance can be assigned to the high oxidation states of the oxide nanoparticles, the strong electrical coupling between these oxides and the CNTs as well as favorable surface properties rendering the hybrids a promising alternative to noble metal based OER catalysts.
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| 14. |
- Xie, Kunpeng, 1985, et al.
(författare)
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Deactivation of Cu-SSZ-13 SCR catalysts by vapor-phase phosphorus exposure
- 2019
-
Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 256
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Tidskriftsartikel (refereegranskat)abstract
- Phosphorus in vehicle exhaust is one of the typical derivatives from fuels and lubricant oils that cause irreversible deactivation of automotive catalysts. In this work, we investigate the deactivation of Cu-SSZ-13 by vapor-phase phosphorus poisoning (100 ppm H3PO4) under NH3-free lean conditions and NH3-SCR operating conditions. The poisoned monolith catalysts were characterized with XPS, ICP-SFMS, SEM-EDX mapping, and H2-TPR. The influence of phosphorus on catalytic performance (i.e. standard NH3-SCR, NH3 oxidation, NO oxidation, NH3 storage, and NO storage) was evaluated. Phosphorus is mainly stored in the form of metaphosphate in poisoned catalysts, and it possesses axial and radial gradients on catalyst washcoats. Phosphorus strongly affects the copper reduction property, as revealed by the shifts in copper reduction to higher temperature in H2-TPR experiments. Variations in phosphorus poisoning conditions are found to mainly impact the amounts of phosphorus captured and stored in the monolith catalysts. In order to elucidate the deactivation mechanism, the deactivation is correlated with the P/Cu ratio. The temperature shift for copper reduction significantly increases with the P/Cu ratio and levels at high Cu/P ratios. The deactivation degrees of NH3 oxidation and NO oxidation as a function of the P/Cu ratio follow the same trend as the copper reduction temperature. This is possibly due to the formation of copper phosphates in the large cages, which deactivates the copper sites for NH3 and NO oxidation. The deactivation for standard NH3-SCR, NH3 storage, and NO storage is proportional to the P/Cu ratio. The impact of phosphorus on NO storage is significantly stronger than on NH3 storage, indicating that greater contribution to deactivation is brought about by the decreased capacity of NO chemisorption.
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| 15. |
- Xie, Kunpeng, 1985, et al.
(författare)
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Influence of phosphorus on Cu-SSZ-13 for selective catalytic reduction of NOx by ammonia
- 2017
-
Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 297, s. 46-52
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Tidskriftsartikel (refereegranskat)abstract
- The influence of phosphorus on Cu-SSZ-13 NH3-SCR catalysts was investigated in order to reveal the deactivation behavior of Cu-SSZ-13 in the presence of phosphorus-containing poisons in the exhaust of diesel engines. The phosphorus-poisoning was simulated by treating the Cu-SSZ-13 catalysts with (NH4)(2)HPO4 aqueous solution using incipient wetness impregnation method. The focus of the study was the effect of phosphorous on the different reactions occurring on the SCR catalyst, including ammonia oxidation, NO oxidation and standard SCR using monolith catalysts. Moreover, characterization such as ICP-SFMS, N-2-physisorption, and NH3-TPD were employed for the evaluation of the physical and chemical properties of the P-impregnated catalysts. Physically blocking of pores and poisoning of acidic sites were observed on the P-impregnated catalysts. In addition, we observed that phosphorus severely suppressed ammonia oxidation and NO oxidation, while its impact on standard SCR reaction was nearly negligible below 300 degrees C. Interestingly, a promotive effect was found at higher temperatures, likely due to the severely inhibiting effect on NH3 oxidation caused by the formation of copper phosphates in the large cages (i.e. 8-membered rings) of Cu-SSZ-13.
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| 16. |
- Xie, Kunpeng, 1985, et al.
(författare)
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Insights into hydrothermal aging of phosphorus-poisoned Cu-SSZ-13 for NH3-SCR
- 2019
-
Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 241, s. 205-216
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Tidskriftsartikel (refereegranskat)abstract
- Automotive catalysts are continuously exposed to different poisons and to high temperature, which result in hydrothermal aging. Phosphorus is one of the poisons that the catalyst could be exposed to and it originates from the lubricant oil. In this work, we study the influence of phosphorus poisoning on the catalytic performance and the deactivation mechanism in the hydrothermal aging of Cu-SSZ-13 catalysts. Phosphorus poisoning was performed by impregnating the Cu-SSZ-13 catalysts with (NH4)2HPO4solution using the incipient wetness impregnation method, which allowed us to precisely control the amount of phosphorus poison on the catalyst. XPS results show that phosphorus oxide (P2O5), metaphosphate (PO3–) and phosphate (PO43–) are formed on the surface of phosphorus-poisoned catalysts, and metaphosphate is the main compound among those species. Phosphorus tends to interact with copper sites and strongly impacts the electronic and reduction property of Cu, as disclosed using EDX mapping, UV–vis DRS and H2-TPR. Results of catalytic activities show that phosphorus poisoning is more severe on ammonia and NO oxidation reactions than on standard ammonia-SCR. This is possibly due to the formation of copper phosphates in the large cages, as revealed using H2-TPR, which reduces the oxidation capacity. Moreover, results of XRD and27Al and31P solid-state NMR reveal that phosphorus not only interacts with copper by forming a P–O–Cu linkage but also partially inserts into the zeolite framework by forming a localized AlPO4phase. Both non-poisoned and P-poisoned catalysts lose their active sites and chabazite structures due to dealumination after successively aging in hydrothermal conditions (8 vol.% O2, 5 vol.% H2O in Ar) at different temperatures (800, 850, and 900 °C), which results in a large decrease in SCR performance. Specifically, the P-poisoned catalysts degrade faster than the non-poisoned catalysts. Results demonstrate that phosphorus induces the extensive formation of AlPO4that accelerates the dealumination during hydrothermal aging. This work provides new insight into understanding the deactivation mechanism in Cu-SSZ-13 from the perspectives of phosphorus-poisoning and hydrothermal aging, and it clearly shows that it is crucial to examine poisoning and hydrothermal aging simultaneously.
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| 17. |
- Xie, Kunpeng, 1985, et al.
(författare)
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Promoting effect of nitrogen doping on carbon nanotube-supported RuO2 applied in the electrocatalytic oxygen evolution reaction
- 2016
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Ingår i: Journal of Energy Chemistry. - : Elsevier BV. - 2095-4956. ; 25:2, s. 282-288
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Tidskriftsartikel (refereegranskat)abstract
- RuO2 nanoparticles supported on multi-walled carbon nanotubes (CNTs) functionalized with oxygen (OCNTs) and nitrogen (NCNTs) were employed for the oxygen evolution reaction (OER) in 0.1 M KOH. The catalysts were synthesized by metal-organic chemical vapor deposition using ruthenium carbonyl (Ru3(CO)12) as Ru precursor. The obtained RuO2/OCNT and RuO2/NCNT composites were characterized using TEM, H2-TPR, XRD and XPS in order probe structure-activity correlations, particularly, the effect of the different surface functional groups on the electrochemical OER performance. The electrocatalytic activity and stability of the catalysts with mean RuO2 particle sizes of 13-14 nm was evaluated by linear sweep voltammetry, cyclic voltammetry, and chronopotentiometry, showing that the generation of nitrogen-containing functional groups on CNTs was beneficial for both OER activity and stability. In the presence of RuO2, carbon corrosion was found to be significantly less severe.
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| 18. |
- Xie, Kunpeng, 1985, et al.
(författare)
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Room temperature synthesis of CdS nanoparticle-decorated TiO 2 nanotube arrays by electrodeposition with improved visible-light photoelectrochemical properties
- 2016
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Ingår i: Electrochemistry Communications. - : Elsevier BV. - 1388-2481. ; 63, s. 56-59
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Tidskriftsartikel (refereegranskat)abstract
- Controllable CdS nanoparticles (NPs) decorated on TiO2 nanotube arrays (NTAs) were prepared via electrodeposition in DMSO solution at room temperature, aiming to improve the photoelectrochemical properties of TiO2 NTA electrode in visible-light region. By tuning the concentrations of sulfur and Cd2+ as well as the deposition time, CdS NPs with different sizes can be controllably synthesized at room temperature. Excellent photocurrent response and incident photo to current conversion efficiency were achieved with smaller CdS NPs with optimal reactant concentrations and deposition time, which can be attributed to highly efficient charge separation and high dispersion of CdS NPs on both inner and outer surfaces of TiO2 nanotubes.
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| 19. |
- Xie, Kunpeng, 1985, et al.
(författare)
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Tuning Ag morphology on TiO2 nanotube arrays by pulse reverse current deposition for enhanced plasmon-driven visible-light response
- 2017
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Ingår i: Journal of Applied Electrochemistry. - : Springer Science and Business Media LLC. - 1572-8838 .- 0021-891X. ; 47:8, s. 959-968
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Tidskriftsartikel (refereegranskat)abstract
- TiO 2 nanotube arrays (NTAs) decorated with controllable Ag particles were prepared by pulse reverse current deposition in AgNO 3 /NaNO 3 aqueous solution, aiming to improve the photoelectrochemical properties of TiO 2 NTA electrode in visible-light region. By tuning the pulse current density and deposited charge density, a controllable synthesis of Ag structures was achieved. Excellent photocurrent responses of TiO 2 NTAs in UV and visible light regions were achieved by depositing Ag nanorods and nanoparticles, which was attributed to highly efficient charge separation by the Schottky junction at the Ag/TiO 2 interface and localized surface plasmon resonance effect of Ag nanostructures. Graphical Abstract: [Figure not available: see fulltext.].
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| 20. |
- Yang, Hengyan, et al.
(författare)
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New Understanding on Photocatalytic Mechanism of Nitrogen-Doped Graphene Quantum Dots-Decorated BiVO4 Nanojunction Photocatalysts
- 2017
-
Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 2:7, s. 3766-3773
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Tidskriftsartikel (refereegranskat)abstract
- Bismuth vanadate (BiVO4) is a promising candidate as a visible-light-driven photocatalyst in the aspect of practical applications. To investigate the origin of active species from BiVO4 and understand the influence of the variations of the photocatalytic process, comparative studies on zero-dimensional nitrogen-doped graphene quantum dot (NGQD)-decorated BiVO4 have been carried out for methylene blue photodegradation. It was found that the hydroxyl group-rich NGQD surface and the established heterojunction structure between NGQDs and BiVO4 were greatly beneficial for the conversion of the MOH radical. With NGQD decoration, the dominant oxidant species for NGQDs/BiVO4 were confirmed to be MOH and H2O2, rather than holes originating from the valence band of unmodified BiVO4. The synergistic photocatalytic mechanism with respect to the interfacial charge transport and the conversion of active species was proposed. The achievement of the controllable active species significantly altering the activity may be applied for different photocatalytic reactions.
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