Understanding the Stability of Etched or Platinized p‑GaInP Photocathodes for Solar-Driven H2 Evolution

• Published in: ACS applied materials & interfaces Vol. 13; no. 48; pp. 57350 - 57361
• Main Authors: Yu, Weilai, Young, James L, Deutsch, Todd G, Lewis, Nathan S
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 08.12.2021; American Chemical Society (ACS)
• Subjects: electrodeposition; Energy, Environmental, and Catalysis Applications; hydrogen-evolution reaction; MATERIALS SCIENCE; photoelectrode; semiconductor; SOLAR ENERGY; tandem solar-fuel generators; tandem solar-fuel generators; hydrogen-evolution reaction; electrodeposition; photoelectrode; semiconductor
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.1c18243

The long-term stability in acidic or alkaline aqueous electrolytes of p-Ga0.52In0.48P photocathodes, with a band gap of ∼1.8 eV, for the solar-driven hydrogen-evolution reaction (HER) has been evaluated from a thermodynamic, kinetic, and mechanistic perspective. At either pH 0 or pH 14, etched p-GaInP electrodes corroded cathodically under illumination and formed metallic In0 on the photoelectrode surface. In contrast, under the same conditions, electrodeposition of Pt facilitated the HER kinetics and stabilized p-GaInP/Pt photoelectrodes against such cathodic decomposition. When held at 0 V versus the reversible hydrogen electrode, p-GaInP/Pt electrodes in either pH = 0 or pH = 14 exhibited stable current densities (J) of ∼−9 mA cm–2 for hundreds of hours under simulated 1 sun illumination. During the stability tests, the current density–potential (J–E) characteristics of the p-GaInP/Pt photoelectrodes degraded due to pH-dependent changes in the surface chemistry of the photocathode. This work provides a fundamental understanding of the stability and corrosion mechanisms of p-GaInP photocathodes that constitute a promising top light absorber for tandem solar-fuel generators.