An ultra-high performance for reduction of 4-nitroaniline with optimized noble-metal-free Bi4NbO8Cl nanosheets under visible light irradiation

Abstract

The reduction conversion of 4-nitroaniline (4-NA) to p-phenylenediamine (PPD) via semiconductor photocatalysis has been considered as one of the most promising technologies to satisfy the requirement of modern industrial development. In this work, Bi4NbO8Cl materials with different calcination temperatures were successfully obtained by a facile synthesis method. Attractively, Bi4NbO8Cl nanosheet was put forward to catalyze 4-nitroaniline into p-phenylenediamine (PPD), which presented an ultra-high performance for the reduction of 4-nitroaniline under visible light irradiation. The optimal Bi4NbO8Cl nanosheets without an additive of noble metal cocatalyst can achieve conversion of 4-nitroaniline into p-phenylenediamine in 5 min. Furthermore, the crystal structure, optical properties, microscopic morphology, element chemical states, and photoelectrochemical properties of these photocatalysts were systematically investigated by various physical and chemical characterizations. Thereinto, Bi4NbO8Cl material displays a uniform morphology of nanosheets, and the size of nanosheets becomes larger and larger with the increase of calcination temperature. Simultaneously, prominent durability and reproducibility were accomplished via the above-mentioned photocatalyst. In addition, the CO2− radicals acting as primary active species can be confirmed by some controlled experiments and active species trapping experiments. This work provides a high-efficiency photocatalyst for the hydrogenation of 4-nitroaniline into p-phenylenediamine (PPD), and a possible reaction mechanism was uncovered and proposed.