Stability remains the most persistent materials challenge towards developing efficienct and stable solar-fuel devices for practical applications. Sustained solar-driven water-splitting at high current density (&gt;10 mA cm-2) requires strong acidic or alkaline aqueous electrolytes (pH=0/14), which can potentially cause severe corrosion of semiconducting light-absorbers. 3-5 semiconductors, including InP, GaAs and GaInP, are attractive light-absorbers for tandem solar-fuel generators, but their long-term stability under hydrogen-evolving reaction (HER) conditions remains to be further elucidated.<br/>In this talk, I will introduce a series of systematic investigations over the stability of these 3-5 semiconductor photocathodes, specifically for the HER at pH=0/14. We used a comprehensive experimental approach to reveal the underlying corrosion chemistry of these materials, by measuring (a) electrode dissolution by ICP-MS, (b) surface changes by XPS, as well as (c) morphological evolution by microscopy. Importantly, we find that both catalytic kinetics and surface stoichiometry are important considerations for defining their corrosion pathways under fuel-forming conditions. Overall, these results emphasize that the physical stability and electrochemical stability of semiconductor photoelectrodes need to be considered separately.

Stability and corrosion chemistry of photo-electrochemical interface for solar fuels

ACS Spring 2022

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