Electronic structure and water splitting under visible light irradiation of BiTa_(1-χ)Cu_χO_4 (χ = 0.00-0.04) photocatalysts

摘要

A series of photocatalysts, BiTa_(1-χ)Cu_χO_4 (χ = 0.00-0.04), were synthesized by the conventional solid-state reaction method and their electronic structures and photocatalytic activities were investigated. The electron microscope observations revealed that the particle sizes of BiTaO_4:Cu crystals were smaller and the surface with many characteristic steps was more obvious than that of the nondoped BiTaO_4, which lead to the increase of photocatalytic activity of water splitting. The UV-vis spectra indicate that the Cu~(2+) ions doping not only enhanced the photocatalytic activity under ultraviolet-visible (λ > 300 nm) light irradiation but also induced the visible light (λ > 400 nm) response. The photocatalyst doped with 2 mol% Cu~(2+) and loaded with 0.3 wt% RuO_2 co-catalyst was found to have the highest activity. New band gap in the visible light range is obtained by copper-doped BiTaO_4, which is attributed to the transition from the donor level resulting from the Cu impurity to the conduction band of BiTaO_4 doped with copper on the basis of the result of DFT calculation.