Catalysts from earth abundant materials in a scalable, stand-alone photovoltaic-electrochemical module for solar water splitting†
We report on the preparation and performance of catalysts from earth abundant materials and their implementation in a stand-alone photovoltaic-electrochemical (PV-EC) module with 64 cm2 active area. NiFeOX as the oxygen evolution reaction catalyst and NiMo as the hydrogen evolution reaction catalyst were electrodeposited on nickel sheets. We compare the NiFeOX/NiMo catalysts to a noble metal catalyst system consisting of IrOX and Pt regarding their potential for upscaling to large areas and their application and performance in the PV-EC module with a triple junction thin film silicon based solar cell. Additionally, we present long-term stability measurements of the catalyst systems (i) NiMo/NiFeOX and (ii) Ni/Ni under simulated day-night cycles. Overall, we show the feasibility of using earth abundant catalysts in an upscaled stand-alone PV-EC module. The NiMo/NiFeOX catalyst pair outperforms the precious metal catalysts with a solar-to-hydrogen efficiency of ηSTH(NiMo/NiFeOX) = 5.1% (ηSTH(Pt/IrOX) = 4.8%) and shows an excellent long-term stability in the simulated day-night cycles.