A BiVO₄ photoanode grown on porous and conductive SnO₂ ceramics for water splitting driven by solar energy

The transformation of solar energy into chemical energy stored as hydrogen fuel underlies the water splitting process into O₂ and H₂ in photo-electrochemical (PEC) cells. This a potentially promising technology to generate renewable and clean energy. To make this technology commercially viable, the engineering of appropriate low-cost and robust photo-electrode materials and substrates is needed. In this study, we introduce BiVO₄-photoelectrodes grown on conductive bulk SnO₂–Sb₂O₅ ceramics acting as porous substrate. For these photoelectrodes, the value of photocurrent density of 1.1 mA/cm² was achieved in 0.1 M NaOH electrolyte at 1.23 V vs. RHE (reversible hydrogen electrode) under LED light (λ = 455 nm). This PEC performance of these BiVO₄ photoelectrodes is reached in spite of using a simple and low-cost deposition technique, where the BiVO₄-precursor is delivered to the bulk porous ceramic substrate as a nebulized aerosol in air-flow at room temperature. The high porosity of the ceramic substrate permits some permeation of the aerogel into the pores to a depth of several micrometers to provide a 3D-growth of the BiVO₄-coating on conductive SnO₂ grains. The film thickness of the BiVO₄ on individual grains is approximately 100 nm. This construction of the photoelectrode leads to an effective interface with good absorption of solar radiation and good electron harvesting. The bulk ceramics assure favorable conditions for electron collection and charge transport, which results in a good PEC performance with this type of photoanode.