The interplay between vanadium and strontium doping in the photoelectrochemical performance of combinatorially deposited single- and dual-doped sodium tantalate thin films

Auteurs

Garlisi C., Rogé V., Menguelti K., Lunca-Popa P., Michel M., Vergne C., Philippe A.M., Wagner E., Maudez W., Benvenuti G., Barborini E.

Référence

Sustainable Materials and Technologies, vol. 41, art. no. e01006, 2024

Description

The rational design of photoanode materials for photoelectrochemical (PEC) water splitting is a critical aspect towards making this technology available for large-scale renewable energy transition. In this respect, we present here the combinatorial tailoring of the PEC performance of sodium tantalate (NaTaO3)-based ternary and quaternary oxide thin films grown by chemical beam vapor deposition. The incorporation of the selected dopants, namely vanadium and strontium, mainly at the B-site of the orthorhombic perovskite NaTaO3 structure, enhanced the distortion of the TaO6 octahedrons with consequent benefits on the charge delocalization. Mott-Schottky analysis combined with optical characterization, revealed important alterations of the band structure with an increase in the donor density and band gap narrowing, the latter being more significant in V/Sr dual-doped oxides (from 4.5 eV in pristine NaTaO3 to a minimum of 3.6 eV in codoped NaTaO3). Despite an anodic shift of the onset potential for water oxidation, the V-doping and especially V/Sr codoping were found to be the most effective in improving the PEC activity under Hg[sbnd]Xe light irradiation, with the best performance observed with Sr and V at optimal doping concentrations of 2 and 3 at.%, respectively. Electrochemical impedance spectroscopy and transient open circuit potential measurements shed the light on the synergistic effects of V and Sr doping in boosting charge separation. Our results demonstrate that V/Sr codoping is a viable route to enhance PEC performance of NaTaO3, mainly due to an increased light-harvesting efficiency, suppression of trap states, and efficient charge transfer to the photoanode/electrolyte interface.

Lien

doi:10.1016/j.susmat.2024.e01006