In situ synthesis of ZnO/ZnTe common cation heterostructure and its visible-light photocatalytic reduction of CO2 into CH4

Abstract

The development of hierarchical superstructures and their application for the sake of clean and sustainable energy is an attractive research field. Here we reported in situ synthesis of common cation heterostructure via modification of zinc oxide (ZnO) by zinc telluride (ZnTe) photocatalyst through one-pot hydrothermal approach at reaction temperature of 180°C. The phase, crystal structure, morphology, composition, optical property and alignment of energy levels of the as-synthesized ZnO/ZnTe heterostructure have been thoroughly studied by different techniques. The heterostructure fabricated with different ZnO flower-like nanostructures (hundreds of nanometers for the rod length or sheet size of the petals and tens of nanometers for the corresponding diameter or thickness) exhibited different photocatalytic capability for reduction of carbon dioxide into methane under visible-light irradiation (λ≥420nm), which is mainly due to the different exposed crystal planes of ZnO and different surface area (15.0 and 5.6m2g−1 for sheet-like petals and rod-like petals, respectively). The obtained photocatalytic systems show good visible-light photoreduction capability even with ∼3.35% ZnTe in terms of atomic percentage, for which the solar energy conversion efficiency can reach ∼3.28% in the first 30min of photoreduction. The formation of heterojunction can facilitate charge transfer and thus improve the photocatalytic activity. In addition, the advantage of sharing common cations for a heterostructure is also briefly discussed.