Photoelectrochemical water splitting cells at elevated pressure using BiVO4 and platinized III-V semiconductor photoelectrodes
Feng Liang, Heejung Kong, Diwakar Suresh Babu, Roel van de Krol, Fatwa F. Abdi
Abstract
Abstract Direct production of pressurized green hydrogen via photoelectrochemical water splitting reduces the need for mechanical compression and mitigates bubble-related losses. However, existing demonstrations have been limited to atmospheric pressure. Here, we bridge this gap by designing, constructing, and testing a high-pressure flow cell for photoelectrochemical water splitting using two configurations. In a back-illuminated BiVO 4 -based photoelectrochemical cell, increased pressure suppresses bubble evolution and alleviates photocurrent saturation under concentrated sunlight: at 10 suns, the photocurrent rises from 3× at 1 bar to ~7× at 5 bar. Direct operando imaging of the electrode surfaces confirms that this improvement comes primarily from suppressed bubble evolution. Conversely, a front-illuminated platinized triple-junction III-V-based photoelectrochemical cell shows limited pressure dependence up to 8 bar due to its dispersed catalyst and long carrier diffusion length. These findings highlight the differing response of photoelectrochemical devices to elevated pressure and demonstrate a viable pathway toward scalable, high-pressure solar-driven hydrogen production.