Interfacial enhancement for hydrogen radical transfer on hollow Cu2O/rGO nanohybrid with efficient catalytic reduction activity

Abstract

The reduction of nitro compounds is of great importance in practical application. Herein, hollow Cu2O/rGO nanohybrid is synthesized by a facile wet-chemical method. The product reveals greatly enhanced catalytic activity toward the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with a reaction rate of 552.8 s−1 g-1, which is attibuted to the synergetic effect between Cu2O and rGO. The effectiveness of the composite toward the reduction of other nitro compounds, such as 2-chloro-4-nitrophenol, was also confirmed. The transfer mechanism of hydrogen radical during catalytic reduction is investigated in details by theoretical calculations to give insight into the enhanced catalytic activity. The result demonstrates hydrogen radical transferred from Cu2O to 4-NP is a thermodynamically favorable process without energy barriers and easily proceeded at room temperature, while the generation of hydrogen radicals is the rate-determining step, which can be promoted by the interfaces constructed by Cu2O and rGO to achieve the enhanced catalytic activity. Finally, a flow experiment is designed and carried out with a commercial filter membrane as catalyst carrier, which reveals fast and 100% conversion efficiency, indicating its great potential in practical industry applications. This work not only develops the nanocomposite catalyst with high activity but also provides a fundamental basis for designing novel catalysts.