Aerosol-Assisted Chemical Vapour Deposition of BiVO₄ Photoanodes for Light-Driven Water Splitting

Bismuth vanadate (BiVO₄) is an outstanding candidate for visible-light driven water splitting due to its low production cost, high stability, low toxicity, and reasonable band gap with well-placed conduction and valence band edges relative to both hydrogen and oxygen evolution potentials.¹ In this presentation, the development and application of new and novel precursor systems tailor-made for the dual-source aerosol-assisted chemical vapour deposition (AACVD) of highly nanostructured, phase-pure monoclinic-scheelite BiVO₄ thin films is outlined. Having identified the ‘best in show’ precursors for AACVD application, the BiVO₄ thin film deposition conditions are optimised for the most suitable precursor ratios and deposition temperatures for high quality films, with variations in nanostructure as a function of deposition time also being investigated in parallel by scanning electron microscopy (SEM). Light-driven water splitting performance is then evaluated using standard techniques including UV/Vis spectroscopy, linear sweep voltammetry under simulated sunlight irradiation, incident photon-to-current efficiency (IPCE) measurements, chronoamperometry, and electrochemical impedance spectroscopy (EIS). Pristine BiVO₄ films yielded photocurrent densities of 1.23 mAcm^-2 at 1.23 V vs RHE, the highest photocurrent density of any CVD-grown BiVO₄ film to date.<br/><br/>The potential of AACVD for semiconductor doping and hybridisation studies are discussed, most importantly the compatibility of new metal precursors with existing ones. This is exemplified by the facile deposition of W-doped BiVO₄ without adding complexity or steps to the process. This work provides a roadmap in which an effective ‘toolbox’ of cross-compatible metal precursors can be rapidly deployed with AACVD to fabricate a range of doped and/or mixed-metal materials with high photocatalytic performance.<br/> <br/> <br/><b>References</b><br/>1 C. Jiang, S. J. A. Moniz, A. Wang, T. Zhang, J. Tang, <i>Chem. Soc. Rev.</i>, 2017, <b>46</b>, 4645–4660.