Defect engineered N-doped black-V2O5 nanostructures for hydrogen production via solar-catalytic water splitting in the presence of different sacrificial agents

Abstract

In this study, vanadium pentoxide (V2O5) is synthesized via hydrothermal method and annealed in a normal and NH3 gas ambience, which led to the formation of pristine and defective-V2O5 systems, respectively. This defective-V2O5 contained both doped-nitrogen and oxygen-vacancies defects, confirmed through XRD and XPS analysis. Interestingly, this process also led to the exfoliation of V2O5 into a 2D layered structure, confirmed by FESEM analysis. A band gap energy of ∼2.11 and 2.26 eV is estimated for the defective and pristine-V2O5, respectively from the Tauc's plots. The solar-catalytic green H2 production efficiency (in mmol g−1 h−1) of the pristine and defective-V2O5 in presence of different sacrificial is investigated and estimated, and it is found to the order of glycerol (2.369) > methanol (1.969) > triethanolamine (1.441) > sodium sulphate/sodium sulfide mixture (1.210) > ethylene glycol (0.967). While accounting the inherent properties of the various sacrificial agents, the observed enhanced efficiency of defective-V2O5 is attributed to their surface-active sites, suitable band structure along with the modulations in the charge carrier separation and transfer characteristics of the system, confirmed through BET, PL, Mott–Schottky, electrochemical impedance, and photocurrent measurements. Further, the cyclic photocatalytic efficiency of defective-V2O5 is found to be consistent in all the 3 cycles in a total period of 9 h. The post-characterizations of the recycled defective-V2O5 system suggested that the developed photocatalyst is stable in terms of its photo-chemical and physical properties, suitable for scale up green H2 productions.