TiO2 encased TaN nanoparticles heterojunction for photocatalytic H2 evolution from aqueous glycerol solution

Steering of photo excitons via interface engineering of semiconductor photocatalysts is key to achieving a stable and efficient photocatalyst for continuous hydrogen production. Among them, the development of binary nanocomposites have several advantages such as larger surface area, effective light harvesting, improved photoexcitons separation for red-ox reactions, and non-corrosive nature has received special attention. In this work, nanocomposite of metallic TaN nanoparticles attached with TiO2 layer was successfully synthesized using hydrothermal method. HR-TEM analysis revealed the formation of metallic TaN wrapped with TiO2 with irregular spherical morphology. Electrochemical analysis revealed that Schottky barrier is formed at the interface between TaN and TiO2, with the barrier potential also being dependent on the wrapped layer thickness. However, the hot electrons diffusion through TiO2 energy states can attend the photocatalytic reaction, only when they pass over the Schottky barrier. TaN plays a key role in boosting photocatalytic activity by promoting the separation and transfer of photoexcitons. As the thickness of the TiO2 layer increases, the rate of H2 production initially increases and then decreases. This is consistent with the trend for layer thickness-dependent photocatalytic hydrogen evolution. In addition to catalytic stability, time on stream, recyclability, and parametric analysis aided in optimization of ideal experimental conditions is revealed. Under optimal conditions, the photocatalyst showed an enhanced rate of H2 generation (18.2 mmol h−1. g−1cat) under simulated solar light irradiation. Schematic representation of plausible mechanism existed in TiO2 encased TaN nanostructure for photocatalytic hydrogen production. [Display omitted] •TiO2 encased TaN nanoparticles were prepared by hydrothermal process and their formation is revealed by HR-TEM analysis.•Diffusion of photo-excited electrons through TiO2 energy states plays key role to attend the photocatalytic reaction.•Schottky junction developed at the interface of TiO2 and TaN will suppress the charge recombiantion process.•Effect of glycerol and catalyst loading to the reaction solution have been optimized to attain the best system.•The optimized TaN@TiO2 (TNTO-10 wt%) system showed 5.2-folds higher H2 production activity than that of pristine TiO2.