Produção e caracterização de fotoeletrodos à base de rutênio e níquel depositados sobre BiVO4

Abstract

Semiconducting metal oxide photoelectrodes such as the BiVO4, with suitable properties to trigger off PEC reactions under sunlight, are commonly applied for testing approaches for modifying materials towards better overall PEC performance, like the junctions of materials or the improvement of fabrication processes, by making them safer and easier to perform. The conventional deposition routes used for the deposition of cocatalysts, such as the ruthenium and nickel oxides, on the photoelectrode surface are complex, involving even occupational risk. In this work, photoelectrodes based on the deposition of ruthenium and nickel onto monoclinic BiVO4 films and onto m-BiVO4 coupled with tungsten oxide and tin oxide layers were fabricated. The technique used for the deposition of the metals was magnetron-sputtering DC, which is user friendly, has low operational cost and has good reproducibility. The photoelectrodes produced were characterized via XRD, SEM, UV-Vis, RBS, XPS and voltammetry techniques. It was studied the photoelectrochemical performance of samples containing SnO2, WOx and BiVO4 with and without Ru and Ni under thermal treatment in air or electrochemically treated. The morphological and chemical modifications induced by an electrochemical treatment cyclic voltammetry (CV), in phosphate buffer solution (pH 6,7), in a sample with Ni were investigated. The effect of the electrochemical treatment was also studied by XPS analysis and SEM images of samples untreated, during the treatment, and by the end of the cycles. The samples with 3s of Ru deposited onto BiVO4 thermally treated and those with Ni deposited for 50, 100 and 200s electrochemically treated have shown an overall improvement in the current density values produced.