Deposition of nanoporous BiVO4 thin-film photocatalyst by reactive magnetron sputtering: Effect of total pressure and substrate

International audienceNanoporous BiVO4 thin films were deposited using reactive magnetronsputtering in Ar and O2 atmosphere, on various substrates,employing pulsed direct-current (DC) power supplies applied tometallic Bi and V targets for rapid deposition. The procedure wasfollowed by a post-annealing treatment in air to crystallize thephotoactive monoclinic scheelite structure. The influence of totalpressure and substrate on the crystal structure, morphology,microstructure, optical and photocatalytic properties of the filmswas investigated. The crystallization of monoclinic scheelitestructure deposited on fused silica substrate starts at 250 °C andthe films are stable up to 600 °C. The morphology of the films israther dense, despite at the high sputtering pressure (>2 Pa),with embedded nanopores. Among the thin films deposited on fusedsilica, the one deposited at 4.5 Pa exhibits the highest porosity(52%), with the lowest bandgap (2.44 eV) and it shows the highestphotocatalytic activity in the degradation of Rhodamine-B (26%after 7 h) under visible light irradiation. The film deposited onthe silicon substrate exhibits the highest photoactivity (53% after7 h). Lack of hypsochromic shift in the UV−Vis temporal absorptionspectra shows the dominance of the chromophore cleavage pathway inthe photodecomposition