Construction of Bi2MoO6/CdS heterostructures with enhanced visible light photocatalytic activity for fuel denitrification

Abstract

In this work, a novel step-scheme (S-scheme) Bi₂MoO₆/CdS heterojunction (HJ) photocatalyst (PC) was successfully prepared by a two-step solvothermal method for the first time. One-dimensional CdS nanorods were prepared by a simple solvothermal method as a synthesis template. Then, a Bi₂MoO₆ precursor was added to obtain a series of Bi₂MoO₆/CdS HJ composite catalytic materials with different morphologies. The photocatalytic performance of the catalyst was investigated by simulating fuel denitration as a probe reaction under visible light excitation (>420 nm). When compared with pure Bi₂MoO₆ and CdS, the 0.65-Bi₂MoO₆/CdS composite shows the highest photocatalytic activity for pyridine degradation. Degradation of pyridine reached 81% after 240 min of visible light excitation. The degradation rate of 0.65-Bi₂MoO₆/CdS reached 0.4471 h⁻¹, which was 1.8 and 3.2 times higher than that of CdS (0.2493 h⁻¹) and Bi₂MoO₆ (0.1427 h⁻¹), respectively. Combined with a series of characterisation results, the improvement in pyridine degradation activity was mainly attributed to (1) the S-scheme HJ structure between Bi₂MoO₆ and CdS, which greatly promoted the separation of photogenerated electrons and holes while retaining its strong redox ability, (2) the large specific surface area, which provided abundant active sites and efficient adsorption performance and catalytic performance, and (3) the special morphology, which induced multiple reflections of light, thereby improving absorption and utilisation of light. Moreover, after four cycles of pyridine denitrification, the samples still exhibited high activity, indicating good stability and recyclability of the composite catalyst. These findings provide a basis for the development of composite PCs for efficient fuel denitration under visible light irradiation.