Engineering of a high-efficiency water splitting photoanode by synergistic effects of doping, compositing, and coupling on TiO2 nanoparticles

Abstract

Highly efficient photoelectrochemical (PEC) water splitting is achieved by Ag doped hierarchical porous TiO2 nanoparticles in compositing with GQDs (TiO2:Ag-GQDs). The unique optical properties of VO2 (m), monoclinic phase of VO2, is a motivation to use it in PEC processes. To further improve the efficiency of TiO2:Ag-GQDs photoanode, it is coupled with undoped and doped VO2 (m) with earth alkali metals. This coupling strategy is used to engineer the interfacial and optical properties and charge separation/transport on the photoanodes for PEC water splitting. Hence, the efficiency of the photoanodes with structures of TiO2:Ag-GQDs/VO2 or (Mg, Ca, Sr, or Ba)-doped VO2 in PEC water splitting process is investigated. A remarkable photocurrent density of 1.5 mA/cm2 at 1.23 V vs. RHE is achieved for FLGs/TiO2:Ag-GQDs/VO2:Ba photoanode. This value is 20 times higher than that of reported previously for pristine TiO2 photoanode (0.07 mA/cm2 at 1.23 V vs RHE).