Understanding the Stability of Etched or Platinized p-GaInP Photocathodes for Solar-Driven H2 Evolution Article Swipe
YOU?
·
· 2021
· Open Access
·
· DOI: https://doi.org/10.1021/acsami.1c18243
· OA: W3217117408
The long-term stability in acidic or alkaline aqueous electrolytes of p-Ga<sub>0.52</sub>In<sub>0.48</sub>P 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 In<sup>0</sup> 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 (<i>J</i>) of ∼-9 mA cm<sup>-2</sup> for hundreds of hours under simulated 1 sun illumination. During the stability tests, the current density-potential (<i>J</i>-<i>E</i>) 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.
