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

Abstract

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.