Elucidating the dynamics and transfer pathways of photogenerated charge carriers in V₂O₅/BiVO₄ heterojunction photoanodes

A transient absorption spectroscopy study

authored by

Chong Siang Yaw, Carsten Günnemann, Detlef W. Bahnemann, Meng Nan Chong

Abstract

Pairing of bismuth vanadate (BiVO₄) with vanadium pentoxide (V₂O₅) forms a Type II heterojunction photoanode, which has been proven to be a high-performance photoanode architecture for efficient photoelectrochemical (PEC) water oxidation. To further support for advanced rational design and improvement of the heterojunction photoanode, it is quintessential to understand the mechanics and properties of photogenerated charge carriers formed. This study aims to probe the dynamics of photogenerated electron-hole pairs formed in pristine photoanode as well as the heterojunction photoanodes using transient absorption spectroscopy (TAS). Relative to the BiVO₄/V₂O₅ structure, modelling and quantification of the decay constant helps in explaining why the V₂O₅/BiVO₄ heterojunction photoanode exhibited a longer lifetime of the photogenerated charge carriers with a lower decay rate constant that leads to a much-improved overall generation of photocurrent density. An oxygen evolving catalyst of nickel oxyhydroxide (NiOOH) was then anchored on the exterior surfaces of the heterojunction photoanode system to further investigate and modify the transfer pathways of the photogenerated charge carriers. Furthermore, the hole- and scavenger-assisted TAS measurements on the BiVO₄/V₂O₅ heterojunction photoanode revealed that the majority of trapped holes species are accumulated within the BiVO₄ layer. The findings suggested that the Type II heterojunction formation in V₂O₅/BiVO₄ could effectively reduce its charge recombination process.

Organisation(s)

Institute of Technical Chemistry

External Organisation(s)

Monash University
Saint Petersburg State University

Type

Article

Journal

Journal of alloys and compounds

Volume

1010

No. of pages

7

ISSN

0925-8388

Publication date

05.01.2025

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Mechanics of Materials, Mechanical Engineering, Metals and Alloys, Materials Chemistry

Sustainable Development Goals

SDG 7 - Affordable and Clean Energy

Electronic version(s)

https://doi.org/10.1016/j.jallcom.2024.177011 (Access: Open)