A photovoltaic-electrolysis system with high solar-to-hydrogen efficiency under practical current densities
Qingran Zhang, Yihao Shan, Jian Pan, Priyank V. Kumar, Mark Keevers, John Lasich, Gurpreet Kour, Rahman Daiyan, Ivan Perez‐Würfl, Lars Thomsen, Soshan Cheong, Junjie Jiang, Kuang‐Hsu Wu, Chao‐Lung Chiang, Kristian Grayson, Martin A. Green, Rose Amal, Xunyu Lu
Abstract
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 H 2 not economical. 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 (Fe 2 O 3 -NiO x H y ) composite, enables the customized AW electrolyzer with unprecedented catalytic performance (e.g., 1 A cm −2 at 1.8 V and 0.37 kgH 2 /m −2 hour −1 at 48 kWh/kgH 2 ). Benefiting from the superior water electrolysis performance, 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, surpassing all previously reported PV-electrolysis systems.