A novel Au-loaded Na2Ta2O6 multifunctional catalyst: Thermocatalytic and photocatalytic elimination of the poisonous nitrobenzene derivatives from wastewater under natural condition

In this work, a series of Au-loaded Na2Ta2O6 nanocomposite photocatalysts were prepared via a chemical reduction process. It was observed the tiny Au nanoparticles (∼5 nm) uniformly anchored on the surface of Na2Ta2O6 nanoparticles with a well crystallized octahedral morphology. The as-prepared samples demonstrated high efficiency and good recyclability toward reduction of toxic nitrobenzenes to nontoxic aminobenzene. Significantly, a very quickly rate of 2666.7 min−1 g−1 under the simulated solar light irradiation was observed for nitrobenzenes (NB) derivatives reduction. It was found 4-nitrophenol can be completely converted to 4- aminobenzene in only 4 min, 2.35 times higher than that in dark. By evaluate activities over several representative support materials under different reaction conditions, a new photo-synergistic catalytic mechanism was proposed. In the thermocatalytic process, the surface plasmons resonance of Au nanoparticles excited by visible light, and the electron transfer from Na2Ta2O6 semiconductor to Au nanoparticle assisted by ultraviolet light, all make the significantly contributions to achieve the efficient reduction of 4-nitrophenol under solar illumination.