Solution Combustion Synthesis and Rapid Screening of Complex Oxides and Their Composites for Photoelectrochemical Solar Energy Conversion

Abstract

Photoelectrochemical (PEC) water splitting using inorganic semiconductors is an attractive route for renewable energy production. However, many scientific and engineering challenges need to be overcome before its commercialization. Screening of potential semiconductor material candidates falls tops the list. Oxide semiconductors offer many advantages such as stability in a variety of electrolytes, diverse range of bandgaps and their Earth-abundance in nature. In this respect many binary metal oxides have been investigated thoroughly; however, unfortunately, a suitable candidate has not been identified. Hence, ternary and quaternary oxides and their composites have emerged as promising alternatives to binary metal oxides. It is no easy task to screen 8000 ternary and 70000 quaternary combinations and this warrants a time-efficient route of synthesis. Herein, we employed a rapid and energy-efficient method, solution combustion synthesis, to investigate the Cu-Bi-V-O complex system. In this way, we synthesized p-CuBi2O4 and a range of its composites with CuO and α-Bi2O3. As the Cu-V-O system consists of multiple ternary oxide compositions, we were able to synthesize CuV2O6, Cu2V2O7 and Cu3V2O8. Moreover, growth conditions for two polymorphs (low-temperature β-phase and high temperature α-phase) of Cu2V2O7 were identified. Rietveld refinements were performed to confirm phase purity as well as to deduce composition for mixed phases. Finally, the PEC performances of these oxides will be discussed under various electrolyte conditions.