Failure Modes of Platinized pn⁺-GaInP Photocathodes for Solar-Driven H₂ Evolution
Abstract
The long-term stability for the hydrogen-evolution reaction (HER) of homojunction pn⁺-Ga_(0.52)In_(0.48)P 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, Eₒ꜀ and Jₚₕ gradually 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.
Additional Information
© 2022 American Chemical Society. Received 29 January 2022. Accepted 13 May 2022. Published online 6 June 2022. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993 and by award DE-SC0022087 from the DOE Office of Basic Energy Sciences. Research was in part carried out at the Molecular Materials Research Center (MMRC) of the Beckman Institute of the California Institute of Technology. Dr. Nathan Dalleska is thanked for assistance with ICP-MS analysis. The authors from NREL acknowledge research support from the HydroGEN Advanced Water Splitting Materials Consortium, established as part of the Energy Materials Network under the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office, under Award Number DE-EE-0008084. This work was authored in part by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy under Contract Number DE-AC36-08GO28308. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes. Jake Evans is thanked for assistance with experiments. The authors declare no competing financial interest.Attached Files
Supplemental Material - am2c01845_si_001.pdf
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Additional details
- Eprint ID
- 115030
- Resolver ID
- CaltechAUTHORS:20220606-736144000
- DE-SC0004993
- Department of Energy (DOE)
- DE-SC0022087
- Department of Energy (DOE)
- DE-EE-0008084
- Department of Energy (DOE)
- DE-AC36-08GO28308
- Department of Energy (DOE)
- Created
-
2022-06-07Created from EPrint's datestamp field
- Updated
-
2022-06-30Created from EPrint's last_modified field
- Caltech groups
- JCAP