Complex Oxides Synthesized via Arc Furnace: a Fast, Direct and Effective Approach to Obtain Functional Materials

Abstract

Complex oxides can present interesting semiconductor properties since the simultaneous presence of different metallic cations can modulate the conduction and valence band edges, affecting the bandgap energy, the onset potential for reactions and also the photocatalyst long-term stability. Here, we demonstrated that the synthesis of multinary oxides, very challenging using “traditional” methodologies, can be fast achieved by melting the precursor binary oxides in an arc furnace. As a proof of concept, arc-melting a mixture of Bi2O3 and V2O5 (Bi:V molar ratio of 1:1.05) resulted in almost pristine BiVO4 (97.3% from Rietveld refinement of X-ray diffraction (XRD) data); photoelectrochemical (PEC) measurements indicated a promising application as a photoanode for O2 evolution reaction. Conversely, the arc-melting of Bi2O3 and WO3 mixture (Bi:W molar ratio of 2:1.15) resulted in the biphasic Bi2WO6/Bi2W2O9; preliminary PEC analysis revealed characteristics of n-type semiconductor electrode with photoactivity under UV irradiation. Finally, the hierarchical Ag@α-AgVO3/Fe2O3 consisted of micrometric Fe2O3 particles decorated by AgVO3 nanoribbons and Ag nanoparticles, was obtained from melting Ag2O, Fe2O3 and V2O5 as precursors (Ag:Fe:V molar ratio of 3:1:2); PEC measurements also revealed possible application as a photoanode. The results for these three materials demonstrated the arc-synthesis as a fast, effective and scalable methodology for synthesizing complex oxides.