Efficient Photocatalytic Hydrogen Production on Defective and Strained Black Bismuth (III) Oxide

TL;DR

This paper reports a novel high-pressure torsion method to create defective and strained black Bi2O3, significantly enhancing its photocatalytic efficiency for hydrogen production through improved light absorption and electron-hole separation.

Contribution

It introduces a new synthesis approach for defective and strained Bi2O3, demonstrating substantial efficiency improvements in photocatalytic water splitting without dopants.

Findings

Ten-fold increase in water splitting efficiency

Enhanced light absorption and reduced electron-hole recombination

Increased valence band energy leading to higher overpotential

Abstract

Bismuth (III) oxide (Bi2O3) has been highly studied as a photocatalyst for green hydrogen production due to its low band gap, yet its efficiency requires enhancement. This study synthesizes a defective and strained black Bi2O3 by severe straining under high pressure, via a high-pressure torsion method, to improve its photocatalytic hydrogen production. The material rich in oxygen vacancies exhibits a ten-fold improvement in water splitting with excellent cycling stability. Such improvement is due to improved light absorption, narrowing band gap and reduced irradiative electron-hole recombination. Moreover, the valence band bottom energy positively increases by straining leading to a high overpotential for hydrogen production. This research highlights the potential of vacancies and lattice strain in developing dopant-free active catalysts for water splitting.