Different Photostability of BiVO4 in Near-pH-Neutral Electrolytes.

Siyuan Zhang,Ibbi Ahmet,Baptiste Gault,Andrea M Mingers,Roel Van De Krol,Karl J J Mayrhofer,Christina Scheu,Joohyun Lim,Olga Kasian,Patrick Schnell,Anna Fischer,Se-Ho Kim,Serhiy Cherevko,Moritz Kölbach

doi:10.1021/acsaem.0c01904

Abstract

Photoelectrochemical water splitting is a promising route to produce hydrogen from solar energy. However, corrosion of photoelectrodes remains a fundamental challenge for their implementation. Here, we reveal different dissolution behaviors of BiVO4 photoanode in pH-buffered borate, phosphate, and citrate (hole-scavenger) electrolytes, studied in operando employing an illuminated scanning flow cell. We demonstrate that decrease in photocurrents alone does not reflect the degradation of photoelectrodes. Changes in dissolution rates correlate to the evolution of surface chemistry and morphology. The correlative measurements on both sides of the liquid–semiconductor junction provide quantitative comparison and mechanistic insights into the degradation processes.

Highlights

Photoelectrochemical water splitting is a promising route to produce hydrogen from solar energy
The quasi Fermi level of holes shifts to more anodic potentials, which can trigger additional anodic reactions and redefine the stability of photoanodes.[19−22] Experimental evidence on stoichiometric BiVO4 dissolution was first documented in phosphate electrolytes using inductively coupled plasma mass spectrometry (ICPMS).[17]
To measure the corrosion rates in operando, we couple the ICPMS with an illuminated scanning flow cell (SFC) to enable fresh electrolytes continuously flowing over the BiVO4 surface.[23]

Summary

Introduction

Photoelectrochemical water splitting is a promising route to produce hydrogen from solar energy. To measure the corrosion rates in operando, we couple the ICPMS with an illuminated scanning flow cell (SFC) to enable fresh electrolytes continuously flowing over the BiVO4 surface.[23] Thin (∼90 nm) and compact BiVO4 films were prepared by pulsed laser deposition (PLD),[24] and pH-buffered borate, phosphate, and citrate electrolytes were respectively introduced through the SFC.

Results

Conclusion