| 1. |
- Kwong, Wai Ling, et al.
(författare)
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Transparent Nanoparticulate FeOOH Improves the Performance of a WO3 Photoanode in a Tandem Water-Splitting Device
- 2016
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:20, s. 10941-10950
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen evolution catalysts (OEC) are often employed on the surface of photoactive, semiconducting photoanodes to boost their kinetics and stability during photoelectrochemical water oxidation. However, the necessity of using optically transparent OEC to avoid parasitic light absorption by the OEC under front-side illumination is often neglected. Here, we show that furnishing the surface of a WO3 photoanode with suitable loading of FeOOH as a transparent OEC improved the photocurrent density by 300% at 1 V versus RHE and the initial photocurrent-to-O-2 Faradaic efficiency from similar to 70 to similar to 100%. The data from the photo-voltammetry, electrochemical impedance, and gas evolution measurements these improvements were a combined result of reduced hole-transfer resistance for water oxidation, minimized surface recombination of charge carriers, and improved stability against photocorrosion of WO3. We demonstrate the utility of transparent FeOOH-coated W(O)3 in a solar-powered, tandem water-splitting device by combining it with a double-junction Si solar cell and a Ni-Mo hydrogen evolution catalyst. This device performed at a solar-to-hydrogen conversion efficiency of 1.8% in near-neutral K2SO4 electrolyte.
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| 2. |
- Sharifi, Tiva, et al.
(författare)
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Maghemite nanorods anchored on a 3D nitrogen-doped carbon nanotubes substrate as scalable direct electrode for water oxidation
- 2016
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 41:1, s. 69-78
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Tidskriftsartikel (refereegranskat)abstract
- A hybrid catalyst 3D electrode for electrochemical water oxidation to molecular oxygen is presented. The electrode comprises needle shaped maghemite nanorods firmly anchored to nitrogen doped carbon nanotubes, which in turn are grown on a conducting carbon paper that acts as efficient current collector. In 0.1 M KOH this hybrid electrode reaches a current density of 1 mA/cm(2) (geometric surface) at an overpotential of 362 mV performing high chronoamperometric stability. The electrochemical attributes point toward efficient catalytic processes at the surface of the maghemite nanorods, and demonstrate a very high surface area of the 3D electrode, as well as a firm anchoring of each active component enabling an efficient charge transport from the surface of the maghemite rods to the carbon paper current collector. The latter property also explains the good stability of our hybrid electrode compared to transition metal oxides deposited on conducting support such as fluorine doped tin oxide. These results introduce maghemite as efficient, stable and earth abundant oxygen evolution reaction catalyst, and provide insight into key issues for obtaining practical electrodes for oxygen evolution reaction, which are compatible with large scale production processes.
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| 3. |
- Sharifi, Tiva, et al.
(författare)
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Toward a Low-Cost Artificial Leaf : Driving Carbon-Based and Bifunctional Catalyst Electrodes with Solution-Processed Perovskite Photovoltaics
- 2016
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Ingår i: Advanced Energy Materials. - : Wiley-Blackwell. - 1614-6832 .- 1614-6840. ; 6:20, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Molecular hydrogen can be generated renewably by water splitting with an artificial-leaf device, which essentially comprises two electrocatalyst electrodes immersed in water and powered by photovoltaics. Ideally, this device should operate efficiently and be fabricated with cost-efficient means using earth-abundant materials. Here, a lightweight electrocatalyst electrode, comprising large surface-area NiCo2O4 nanorods that are firmly anchored onto a carbon-paper current collector via a dense network of nitrogen-doped carbon nanotubes is presented. This electrocatalyst electrode is bifunctional in that it can efficiently operate as both anode and cathode in the same alkaline solution, as quantified by a delivered current density of 10 mA cm(-2) at an overpotential of 400 mV for each of the oxygen and hydrogen evolution reactions. By driving two such identical electrodes with a solution-processed thin-film perovskite photovoltaic assembly, a wired artificial-leaf device is obtained that features a Faradaic H-2 evolution efficiency of 100%, and a solar-to-hydrogen conversion efficiency of 6.2%. A detailed cost analysis is presented, which implies that the material-payback time of this device is of the order of 100 days.
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