Perfect Matching Factor between a Customized Double-Junction GaAs Photovoltaic Device and an Electrolyzer for Efficient Solar Water Splitting

A photovoltaic (PV) device of double-junction GaAs/GaAs was customized to match up with the current density–voltage property of an efficient electrolyzer with a FeNiWOx/nickel foam (NF) anode and a Pt/NF cathode. The customization of the PV device resulted in a perfect matching factor (MF = 99%) in performances between the PV device and the electrolyzer for solar water splitting in a PV-electrolyzer (PVE) system. Efficient and stable (one-month) solar water splitting with a high solar-to-hydrogen efficiency (STH) of 13.9% was demonstrated under 1 sun irradiation conditions. The STH value is comparable with the top values (14.2–16%) in the state-of-art PVE systems. The high STH is based on an obvious progeny of the highest electricity-to-hydrogen efficiency (ETH = 85%) for the electrolyzers among the PVE systems with the non-precious metal-based anode in the electrolyzer and the perfect MF value (99%). This demonstrates that the perfect matching between the PV devices and the electrolyzers, as well as the development of the efficient electrolyzer successfully contribute to substantial improvement of STH and stability.