High performance III-V photoelectrodes for solar water splitting via synergistically tailored structure and stoichiometry

Haneol Lim,James L Young,Todd G Deutsch,Jongseung Yoon,Daniel J Friedman,John F Geisz

doi:10.1038/s41467-019-11351-1

Haneol Lim, James L Young + Show 4 more

Open Access

https://doi.org/10.1038/s41467-019-11351-1

Copy DOI

Abstract

Catalytic interface of semiconductor photoelectrodes is critical for high-performance photoelectrochemical solar water splitting because of its multiple roles in light absorption, electrocatalysis, and corrosion protection. Nevertheless, simultaneously optimizing each of these processes represents a materials conundrum owing to conflicting requirements of materials attributes at the electrode surface. Here we show an approach that can circumvent these challenges by collaboratively exploiting corrosion-resistant surface stoichiometry and structurally-tailored reactive interface. Nanoporous, density-graded surface of ‘black’ gallium indium phosphide (GaInP2), when combined with ammonium-sulfide-based surface passivation, effectively reduces reflection and surface recombination of photogenerated carriers for high efficiency photocatalysis in the hydrogen evolution half-reaction, but also augments electrochemical durability with lifetime over 124 h via strongly suppressed kinetics of corrosion. Such synergistic control of stoichiometry and structure at the reactive interface provides a practical pathway to concurrently enhance efficiency and durability of semiconductor photoelectrodes without solely relying on the development of new protective materials.

Highlights

Catalytic interface of semiconductor photoelectrodes is critical for high-performance photoelectrochemical solar water splitting because of its multiple roles in light absorption, electrocatalysis, and corrosion protection
The change of surface morphology observed after the stability test with nanostructured, (NH4)2S-treated GaInP2 might be attributed to the desorption and re-adsorption of Ga, In, P, or S atoms at the catalytic interface, through either faradaic or non-faradaic processes, with the latter independent of corrosion reactions that would be parasitic to the photocurrent
The nanoporous morphology was maintained in ways that produce similar levels of reflectance and light absorption, and the photocurrent to those obtained before the stability test

Summary

Introduction

Catalytic interface of semiconductor photoelectrodes is critical for high-performance photoelectrochemical solar water splitting because of its multiple roles in light absorption, electrocatalysis, and corrosion protection. Nanoporous, density-graded surface of ‘black’ gallium indium phosphide (GaInP2), when combined with ammonium-sulfide-based surface passivation, effectively reduces reflection and surface recombination of photogenerated carriers for high efficiency photocatalysis in the hydrogen evolution half-reaction, and augments electrochemical durability with lifetime over 124 h via strongly suppressed kinetics of corrosion Such synergistic control of stoichiometry and structure at the reactive interface provides a practical pathway to concurrently enhance efficiency and durability of semiconductor photoelectrodes without solely relying on the development of new protective materials. Systematic studies of optical, morphological, compositional, and electrochemical properties, together with numerical optical modeling based on finite-difference time-domain method, provide quantitative description of underlying scientific principles in the reported system based on GaInP2, a key material that can make an immediate impact to the development of ultrahigh efficiency solar-driven water splitting systems

Methods

Results

Conclusion