Band Edge Energy Tuning through Electronic Character Hybridization in Ternary Metal Vanadates

Abstract

In the search for photoanode materials with band gaps suitable for utilization in solar fuel generation, approximately 1.2–2.8 eV, theory-guided experiments have identified a variety of materials that meet the band gap requirements and exhibit operational stability in harsh photoelectrochemical environments. In particular, M-V-O compounds (M is a transition metal or main group element) with VO4 structural motifs were predicted to show a remarkably wide range of band energetics (>3 eV variation in the energy of valence band maximum) and characteristics, depending on the M and crystal structure, which is beyond the extent of electronic structured tuning observed in previously studied families of metal oxide photoanodes. While this finding guided experimental discovery of new photoanode materials, explicit experimental verification of the theoretical prediction of the tunable electronic structure of these materials has been lacking to date. In this study, we use X-ray photoelectron spectroscopy and Kelvin probe microscopy to experimentally investigate the electronic structure of M-V-O photoanodes, enabling comparison to theory on a common absolute energy scale. The results confirm the prediction that band edge energies of ternary vanadates vary significantly with metal cations. The valence band variation of approximately 1 eV observed here is larger than that reported in any analogous class of metal oxide semiconductors and demonstrates the promise of tuning the metal oxide electronic structure to enable efficient photoelectrocatalysis of the oxygen evolution reaction and beyond. Because midgap states can hamper realization of the high photovoltage sought by band edge tuning, we analyze the electronic contributions of oxygen vacancies for the representative photoanode V4Cr2O13 to guide future research on the development of high-efficiency metal oxide photoanodes for solar fuel technology.

The Materials Provenance Store

“…2). (2023) 10:184 | https://doi.org/10.1038/s41597-023-02107-0 www.nature.com/scientificdata www.nature.com/scientificdata/ results using traditional experimental methods for catalysts 14,[24][25][26] , photocatalysts 27,28 , and integrated photoanodes [29][30][31] . For each of these examples, the instrument control software was written to validate metadata tracking by 2 primary methods, automated metadata recording and manual data entry with validation.…”

Catechol exerts anin situsurface oxygen vacancy effect on BiOI: an innovative signal transduction mode for cathodic photoelectrochemistry

“…8 Surface V O can introduce new energy levels around the valence band (VB) or conduction band (CB) of semiconductors, thereby regulating either the photophysical or photochemical properties. 9 To date, surface V O has been successfully explored in solar cells, 10 photocatalysis, 11 and photoelectrocatalysis 12 to improve the performances of semiconductors. The common methods of introducing V O generally occur during the preparation of materials, e.g., reduction by reducing agents, ion doping, high temperature and/or pressure reactions, and light irradiation.…”

Bioinduced Surface Oxygen Vacancies on Bismuth Trioxide Nanocrystals for Photocathodic Bioassays

“…This is because the surface V O can change the surface electronic structure and introduce new energy levels around the conduction bands (CBs) or valence bands (VBs), thus modulating either photophysical or photochemical properties of semiconductors . Previously, the introduction of surface V O was generally realized by high pressure and/or temperature reactions, light irradiation, ion doping, or chemical reduction during the materials’ preparation and has been successfully applied in the fields of photocatalysis, photoelectrocatalysis, solar cells, etc. Though the above indicated methods are valid for the introduction of surface V O , they are usually perplexed by complicated and time-consuming operations.…”