| 1. |
- Anil, Athira, et al.
(författare)
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Effect of pore mesostructure on the electrooxidation of glycerol on Pt mesoporous catalysts
- 2023
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 11:31, s. 16570-16577
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Tidskriftsartikel (refereegranskat)abstract
- Glycerol is a renewable chemical that has become widely available and inexpensive due to the increased production of biodiesel. Noble metal materials have shown to be effective catalysts for the production of hydrogen and value-added products through the electrooxidation of glycerol. In this work we develop three platinum systems with distinct pore mesostructures, e.g., hierarchical pores (HP), cubic pores (CP) and linear pores (LP); all with high electrochemically active surface area (ECSA). The ECSA-normalized GEOR catalytic activity of the systems follows HPC > LPC > CPC > commercial Pt/C. Regarding the oxidation products, we observe glyceric acid as the main three-carbon product (3C), with oxalic acids as the main two-carbon oxidation product. DFT-based theoretical calculations support the glyceraldehyde route going through tartronic acid towards oxalic acid and also help understanding why the dihydroxyacetone (DHA) route is active despite the absence of DHA amongst the observed oxidation products.
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| 2. |
- Greijer, Björn, et al.
(författare)
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Functional Nanostructures from Sol–Gel Synthesis Using Keggin Polyoxometallate Phosphotungstic Acid as a Precursor
- 2024
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Ingår i: Inorganic Chemistry. - 0020-1669 .- 1520-510X. ; 63:7, s. 3428-3435
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Tidskriftsartikel (refereegranskat)abstract
- Subjecting phosphotungstic acid solutions to low pH in combination with introduction of polyvalent cations led to the formation of nanostructured microspheres of approximately 2 μm in size, as shown by scanning electron microscopy, which were almost insoluble and resistant to degradation at neutral and high pH. These microspheres were composed of secondary nanospheres with diameters around 20 nm as revealed by transmission electron microscopy and atomic force microscopy. Investigations of the crystal structure of a potential intermediate of this process, namely, acidic lanthanum phosphotungstate, [La(H2O)9](H3O)3[PW12O40]2(H2O)19, showed a tight network of hydrogen bonding, permitting closer packing of phosphotungstic acid anions, thereby confirming the mechanism of the observed self-assembly process. The new material demonstrated promising electrochemical properties in oxygen evolution reactions with the high stability of the obtained electrode material.
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| 3. |
- Sahu, Tushar Kanta, et al.
(författare)
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Electrochemical Seawater Oxidation by (Ni,Co)3O4-RuO2 Catalysts at Neutral pH in a Forward Osmosis Cell
- 2024
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Ingår i: ACS Applied Energy Materials. - 2574-0962. ; 7:10, s. 4445-4453
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Tidskriftsartikel (refereegranskat)abstract
- Using seawater to generate green hydrogen through electrolysis is a promising strategy for energy conversion. However, direct seawater splitting to form green hydrogen suffers drawbacks from electrode corrosion due to chlorine and other impurities. Herein, we demonstrate direct electrochemical seawater splitting using a forward osmosis membrane coupled with an electrolysis cell. By using this cell, high activity (270 mV at 10 mA/cm(2)) and decent stability (up to 6 days) are achieved by utilizing RuO2-(Ni,Co)(3)O-4 catalyst in a neutral electrolyte. This system is further studied in various electrolytes under neutral to alkaline conditions. This proof of concept shows that seawater splitting could be coupled with semipermeable membranes, allowing for direct utilization of seawater without pretreatment or purification and evading the challenges posed by impurities.
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| 4. |
- Terekhina, Irina, et al.
(författare)
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Electrocatalytic Oxidation of Glycerol to Value-Added Compounds on Pd Nanocrystals
- 2023
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 6:13, s. 11211-11220
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Tidskriftsartikel (refereegranskat)abstract
- Pd octahedral, rhombic dodecahedral, and cubic nanoparticles (PdOCTA, PdRD, and PdCUBE NPs) were synthesized, characterized, and studied as catalysts for the glycerol electrooxidation reaction (GEOR) in a strongly alkaline medium at 20 and 60 °C. The highest mass activity of 0.050 and 0.183 mA/μgPd was observed on PdOCTA at 20 and 60 °C, respectively, whereas PdCUBE exhibited the highest specific activity of 1.49 and 12.84 mA/cmPd2, respectively. The GEOR products were analyzed by high-performance liquid chromatography (HPLC), and their selectivity and overall glycerol conversion were evaluated at 0.86 V vs RHE. The selectivity toward the three-carbon chain (C3) GEOR products was similar for the different types of catalysts, with PdOCTA and PdCUBE NPs achieving more than 50% selectivity at 20 °C and more than 60% at 60 °C. Glycerate was the overall dominant product for all catalysts, with a selectivity of up to 42%. The glycerol conversion was found to be highest for PdOCTA─21% at 20 °C and 82% at 60 °C, while PdRD was the least active and showed less than 3% conversion at 20 °C and 35% at 60 °C. Based on the GEOR product distribution, a reaction mechanism was proposed.
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| 5. |
- Terekhina, Irina, 1994-
(författare)
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On selective glycerol valorisation : Exploring the performance of facet-controlled nanoelectrocatalysts
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As the biodiesel industry's growth skyrocketed in the past 20 years, it resulted in the accumulation of its main by-product—glycerol. Despite its extensive applications in the pharmaceutical industry, medicine, cosmetics, agriculture, and food industries, the supply exceeds the demand. Hence, glycerol, being abundant and cheap, has emerged as a promising feedstock for producing value-added chemicals. One of the tactics to generate those products is the glycerol electrooxidation reaction (GEOR), where glycerol is oxidised at the anode and hydrogen gas is generated at the cathode.In the present thesis, noble metal-based nanoparticles were synthesised, characterised, and evaluated in alkaline media as catalysts for the GEOR. In order to assess and optimise the electrocatalytic performance and selectivity of the GEOR toward three-carbon (C3) products, different parameters like the morphology and composition of the catalyst, exposed crystallographic facets, electrolyte composition and electrolysis potential were studied.The centre of the attention of the research covered were Pd, Pd-Ni, Pt and Pt-Co nanoparticles with an octahedral, rhombic dodecahedral, and cubic shape and more irregular shapes. Cubic-shaped catalysts with {100} faces were the best-performing among the investigated systems. In addition, alloying of Pd and Pt with non-noble Ni and Co improved the efficiency of the GEOR compared to their noble monometallic counterparts while generally retaining the selectivity of C3 products mostly represented by glycerate and lactate.
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| 6. |
- White, Jai, et al.
(författare)
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Glycerol Electrooxidation at Industrially Relevant Current Densities Using Electrodeposited PdNi/Nifoam Catalysts in Aerated Alkaline Media
- 2023
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 170:8
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Tidskriftsartikel (refereegranskat)abstract
- Through glycerol electrooxidation, we demonstrate the viability of using a PdNi catalyst electrodeposited on Ni foam to facilitate industrially relevant rates of hydrogen generation while concurrently providing valuable organic chemicals as glycerol oxidation products. This electrocatalyst, in a solution of 2 M NaOH and 1 M glycerol at 80 °C, enabled current densities above 2000 mA cm−2 (in a voltammetric sweep) to be obtained in atmospheres of both air and N2. Repeated potential cycling under an aerated atmosphere to these exceptional current densities indicated a high stability of the catalyst. Through steady state polarisation curves, 1000 mA cm−2 was reached below an anodic potential of 0.8 V vs RHE. Chronoamperometry showed glycerate and lactate being the major oxidation products, with increased selectivity for lactate at the expense of glycerate in aerated systems. Aerated atmospheres were demonstrated to consistently increase the apparent Faradaic efficiency to >100%, as determined by the concentration of oxidation products in solution. The excellent performance of PdNi/Ni in aerated solutions suggests that O2 removal from the electrolyte is not needed for an industrial glycerol electrooxidation process, and that combining electrochemical and chemical glycerol oxidation, in the presence of dissolved O2, presents an important process advantage.
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| 7. |
- White, Jai, et al.
(författare)
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Synergistic Bimetallic PdNi Nanoparticles : Enhancing Glycerol Electrooxidation while Preserving C3 Product Selectivity
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Electrochemical conversion of glycerol offers a promising route to synthesise value-added glycerol oxidation products (GOPs) from an abundant biomass-based resource. While noble metals provide a low overpotential for the glycerol electrooxidation reaction (GEOR) and high selectivity towards three-carbon (C3) GOPs, their efficiency and cost can be improved by incorporating non-noble metals. Here, we introduce an effective strategy to enhance the performance of Pd nanoparticles for the GEOR by alloying them with Ni. The resulting PdNi nanoparticles show a significant increase in both specific activity (by almost 60%) and mass activity (by almost 25%) during the GEOR at 40 °C. Additionally, they exhibit higher resistance to deactivation compared to pure Pd. Analysis of the GOPs reveals that the addition of Ni into Pd does not compromise the selectivity, with glycerate remaining at around 60% of the product fraction, and the other major product being lactate at around 30%. Density functional theory calculations confirm the reaction pathways and the basis for the higher activity of PdNi. This study demonstrates a significant increase in the GEOR catalytic performance, while maintaining the selectivity for C3 GOPs, using a more cost-effective nanocatalyst.
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| 8. |
- White, Jai, et al.
(författare)
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Synergistic Bimetallic PdNi Nanoparticles : Enhancing Glycerol Electrooxidation While Preserving C3 Product Selectivity
- 2024
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Ingår i: ACS Applied Energy Materials. - 2574-0962. ; 7:5, s. 1802-1813
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical conversion of glycerol offers a promising route to synthesize value-added glycerol oxidation products (GOPs) from an abundant biomass-based resource. While noble metals provide a low overpotential for the glycerol electrooxidation reaction (GEOR) and high selectivity toward three-carbon (C3) GOPs, their efficiency and cost can be improved by incorporating non-noble metals. Here, we introduce an effective strategy to enhance the performance of Pd nanoparticles for the GEOR by alloying them with Ni. The resulting PdNi nanoparticles show a significant increase in both specific activity (by almost 60%) and mass activity (by almost 35%) during the GEOR at 40 °C. Additionally, they exhibit higher resistance to deactivation compared to pure Pd. Analysis of the GOPs reveals that the addition of Ni into Pd does not compromise the selectivity, with glycerate remaining at around 60% of the product fraction and the other major product being lactate at around 30%. Density functional theory calculations confirm the reaction pathways and the basis for the higher activity of PdNi. This study demonstrates a significant increase in the GEOR catalytic performance while maintaining the selectivity for C3 GOPs, using a more cost-effective nanocatalyst.
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| 9. |
- Xi, Ning, et al.
(författare)
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Polyhedral Coordination Determined Co-O Activity for Electrochemical Oxidation of Biomass Alcohols
- 2023
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Ingår i: Advanced Energy Materials. - 1614-6832 .- 1614-6840. ; 13:37
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Tidskriftsartikel (refereegranskat)abstract
- Earth-abundant transition metal oxides are promising electrocatalysts for oxidation of biomass alcohols. Here, CoO and Co3O4 are selected as representative cobalt oxide catalysts and grown on carbon fiber paper (CFP) electrodes to reveal the interplay between electronic structure and catalytic activity of catalysts for oxidation of glycerol, diols, and monohydric alcohols. In situ electrochemical tests elucidate that the CoO/CFP electrode has lower interfacial impedance, higher charge transfer, faster oxidation rate, and thereby the higher catalytic activity for alcohol oxidation than the Co3O4/CFP electrode. Especially for glycerol oxidation, the CoO/CFP electrode only requires 1.32 V to reach 10 mA cm−2, the potential is 120 mV lower than that for the Co3O4/CFP electrode. The CoO/CFP electrode can also produce value-added products such as formate, acetate, and glycolate with high selectivity and efficiency at low energy consumptions from oxidation of biomass alcohols. Theoretical calculations further confirm the dominant role of octahedrally coordinated Co-O sites in adsorption, activation, and oxidation of C3-C1 alcohols. This work sheds light on the design of highly efficient transition metal oxide catalysts for oxidation of alcohols by populating octahedral sites in the crystal structure.
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| 10. |
- Yu, Xiaowen, et al.
(författare)
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Electrocatalytic Glycerol Oxidation with Concurrent Hydrogen Evolution Utilizing an Efficient MoOx/Pt Catalyst
- 2021
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 17:44
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Tidskriftsartikel (refereegranskat)abstract
- Glycerol electrolysis affords a green and energetically favorable route for the production of value-added chemicals at the anode and H2 production in parallel at the cathode. Here, a facile method for trapping Pt nanoparticles at oxygen vacancies of molybdenum oxide (MoOx) nanosheets, yielding a high-performance MoOx/Pt composite electrocatalyst for both the glycerol oxidation reaction (GOR) and the hydrogen evolution reaction (HER) in alkaline electrolytes, is reported. Combined electrochemical experiments and theoretical calculations reveal the important role of MoOx nanosheets for the adsorption of glycerol molecules in GOR and the dissociation of water molecules in HER, as well as the strong electronic interaction with Pt. The MoOx/Pt composite thus significantly enhances the specific mass activity of Pt and the kinetics for both reactions. With MoOx/Pt electrodes serving as both cathode and anode, two-electrode glycerol electrolysis is achieved at a cell voltage of 0.70 V to reach a current density of 10 mA cm−2, which is 0.90 V less than that required for water electrolysis.
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