Cost‐Efficient Photovoltaic‐Water Electrolysis over Ultrathin Nanosheets of Cobalt/Iron–Molybdenum Oxides for Potential Large‐Scale Hydrogen Production

Unassisted photovoltaic (PV) water splitting to hydrogen system is of great potential for future environmental‐friendly fuel production from renewable solar energy. However, industrialization simultaneously requires higher efficiency, sustained stability and a lower cost for the system. In this work, the ultrathin cobalt/iron–molybdenum oxides nanosheet on nickel foam (NF) is prepared for efficient HER and OER, respectively, delivering a relatively low voltage of 1.45 V at 10 mA cm−2 in two‐electrodes configuration. Water electrolysis at low voltage driven by electrocatalysts is critical for realizing energy conversion. Integrated with a commercial monocrystalline silicon cell, the H2 area specific activity of 0.47 L m−2 h−1 is achieved with a solar‐to‐hydrogen efficiency of 15.1% under solar simulator illumination (100 mW cm−2) and no performance degradation appeares over 160 h. Such a solar conversion technology demonstrates the potential for long‐term and cost‐efficient H2 production in large‐scale industrialization and provides an exploration for new‐type of energy‐conversion system. Ni foam‐supported ultrathin cobalt/iron–molybdenum oxides nanosheet with two‐way design delivers efficient water electrolysis. The integrated photovoltaic‐water splitting system achieves sustained and steady H2 production with solar‐to‐hydrogen (STH) efficiency of 15.1% over 160 h and H2 area specific activity of 0.47 L m−2 h−1 under solar simulator irradiation (100 mW cm−2).