Failure Modes of Platinized pn+-GaInP Photocathodes for Solar-Driven H2 Evolution

Weilai Yu, Pakpoom Buabthong, James Young, Zachary Ifkovits, Sean Byrne, Myles Steiner, Todd Deutsch, Nathan Lewis

Research output: Contribution to journalArticlepeer-review

4 Scopus Citations

Abstract

The long-term stability for the hydrogen-evolution reaction (HER) of homojunction pn+-Ga0.52In0.48P photocathodes (band gap = 1.8 eV) with an electrodeposited Pt catalyst (pn+-GaInP/Pt) has been systematically evaluated in both acidic and alkaline electrolytes. Electrode dissolution during chronoamperometry was correlated with changes over time in the current density-potential (J-E) behavior to reveal the underlying failure mechanism. Pristine pn+-GaInP/Pt photocathodes yielded an open-circuit photopotential (Eoc) as positive as >1.0 V vs the potential of the reversible hydrogen electrode (RHE) and a light-limited current density (Jph) of >12 mA cm-2(1-sun illumination). However, Eocand Jphgradually degraded at either pH 0 or pH 14. The performance degradation was attributed to three different failure modes: (1) gradual thinning of the n+-emitter layer due to GaInP dissolution in acid; (2) active corrosion of the underlying GaAs substrate at positive potentials causing delamination of the upper GaInP epilayers; and (3) direct GaAs/electrolyte contact compromising the operational stability of the device. This work reveals the importance of both substrate stability and structural integrity of integrated photoelectrodes toward stable solar fuel generation.

Original languageAmerican English
Pages (from-to)26622-26630
Number of pages9
JournalACS Applied Materials and Interfaces
Volume14
Issue number23
DOIs
StatePublished - 15 Jun 2022

Bibliographical note

Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.

NREL Publication Number

  • NREL/JA-5900-83272

Keywords

  • failure mode
  • III-V semiconductor
  • photoelectrochemistry
  • solar fuels
  • water splitting

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