High-efficiency Solar-to-Hydrogen Conversion through an Integrated Concentrator Photovoltaic Electrolysis

The photovoltaic-alkaline water (PV-AW) electrolysis system offers an appealing approach for large-scale green hydrogen generation. However, current PV-AW systems suffer from low solar-to-hydrogen (STH) conversion efficiencies (e.g. <20%) at practical current densities (e.g. >100 mA cm^-2), rendering the produced H₂ not economical.^[1] Here, we designed and developed a highly efficient PV-AW system that mainly consists of a customized, state-of-the-art AW electrolyzer and concentrator photovoltaic (CPV) receiver. The highly efficient anodic oxygen evolving catalyst, consisting of an iron oxide/nickel (oxy)hydroxide (Fe₂O₃-NiO_xH_y) composite, enables the customized AW electrolyzer with unprecedented catalytic performance (e.g. 1 A cm^-2 at 1.8 V, 0.37 kgH₂/m^-2h^-1 at 48 kWh/kgH₂). Benefiting from the superior water electrolysis performance and the efficient heat management between CPV and AW devices, the integrated CPV-AW electrolyzer system reaches a very high STH efficiency of up to 29.1% (refer to 30.3% if the lead resistance losses are excluded) at large current densities, which surpasses all previously reported PV-electrolysis systems.^[2]

References

[1] Holmes-Gentle, I., Saurabh, Tembhurne, S., Suter, C., Haussener, S., 2023. Kilowatt-scale solar hydrogen production system using a concentrated integrated photoelectrochemical device. Nat Energy 8, 586–596.

[2] Zhang, Q., Shan, Y., Pan, J., Kumar, P., Keevers, M. J., Lasich, J., Kour, G., Daiyan, R., Perez-Wurf, I., Thomsen, L., Cheong, S., Jiang, J., Wu, K., Chiang, C., Grayson K., Green, M. A., Amal, R., Lu, X., 2025. A Photovoltaic-Electrolysis System with High Solar-to-Hydrogen Efficiency under Practical Current Densities. Sci. Adv., in press.