Solar Water Splitting Using Earth‐Abundant Electrocatalysts Driven by High‐Efficiency Perovskite Solar Cells

Hydrogen is considered as the "holy grail" for the energy community. One of the most promising strategies to produce hydrogen is to split water using renewable energy such as solar radiation. The abundance of water and solar energy enables the potential of scaling-up of this new technology, if suitable electrocatalysts and solar cells are developed. In this work, a series of materials made of earth-abundant elements was investigated for hydrogen evolution or oxygen evolution reaction. Among the developed catalysts, MoS₂ and NiFe showed the best activities for proton reduction and water oxidation, respectively. These catalysts were further integrated into an alkaline electrolyzer, which delivered a current density of 10 mA cm^-2 at a cell voltage of 1.9 V for water splitting. Using two in-series-connected perovskite solar cells (PSCs) as a power source, a remarkable solar-to-hydrogen conversion efficiency of 12.67 % was achieved in an alkaline electrolyzer with a partial current density of 10.3 mA cm^-2 for hydrogen production. The usage of earth-abundant catalysts in this study, together with the employment of low-cost perovskite light absorber, shows the potential of scaling up this type of photovoltaic electrolyzer for sustainable hydrogen production.