Boosting charge migration in VO nanorods by niobium doping for enhanced photocatalytic activity

This work aims to enhance the functionality of V 2 O 5 nanorods by niobium ion doping and discusses its effects on the photocatalytic activity of V 2 O 5 . As reflected in various structural and optoelectronic analyses, the dopant ions had a profound influence on the hydrothermally developed samples, which resulted in tailored nanorod architectures, improved crystallinity, and higher charge generation and separation. The similar dimensions and oxidation states of niobium and vanadium atoms have led to smooth substitutional doping among the layers of VO 5 square pyramids constituting the orthorhombic V 2 O 5 unit crystals. This has led to the hybridization of V 3d and Nb 4d orbitals, which markedly improved their electronic conductivity. The boosted charge kinetics resulted in an optimum band gap of 2.0 eV and the least electron hole recombination in the 2 mol% Nb-doped samples. Accordingly, the 2 mol% Nb-doped samples achieved maximum photocatalytic degradation of complex organic caffeine, removing 91% in 2 hours. The 2 mol% Nb-doped samples also achieved maximum photocurrent generation in a photoelectrochemical cell. However, doping beyond 2 mol% deteriorated the catalytic activity due to the formation of mixed crystalline phases with excess Nb 5+ ions acting as electron hole recombination centres, resulting in poor charge transfer kinetics. The experimental results have been verified by DFT calculations on pure and doped unit cell geometries, which further revealed the synergistic influence of V 3d and Nb 4d orbitals in modifying the band gap of Nb-doped V 2 O 5 . Thus this work presents a rational design and thorough investigation of Nb-doped V 2 O 5 nanorods for enhanced photocatalytic activity. Niobium dopants have improved the structural and optoelectronic properties of V 2 O 5 nanorods, resulting in enhanced charge kinetics for photocatalytic and photoelectrochemical activity.