Novel carbon-nitride based catalysts for enhanced CH4 reforming under visible light: From morphology to heterojunction design principles

Abstract

The synthesis of high value-added chemical products using CO2 and CH4 is a promising CO2 conversion technology that can reduce greenhouse gas emissions while also alleviating the energy crisis. However, problems such as high energy consumption and strict reaction conditions in reforming process hinder the further development of the technology. In this work, carbon-nitrogen based composites were prepared for the first time according to the design principle from morphology to heterojunction, which is innovatively applied in the process of photocatalytic CH4 reforming. Firstly, C3N4 materials with different dimensions (D) are prepared and applied to a CO2-CH4 photocatalytic system. Additionally, the 2D/2D TiO2/g-C3N4 heterostructure is constructed with the ultrasonic impregnation method to further improve charge generation, transfer, and separation efficiency. It is worth noting that the yield of CO reaches 173.80 μmol g−1, and the catalytic performance is improved by 1546% compared to bulk C3N4. Moreover, the physical and chemical properties of 2D/2D TiO2/g-C3N4 materials are studied using a variety of characterization methods. Furthermore, the work function and adsorption energy of different C3N4/TiO2 models for CO2 adsorption are calculated by density functional theory (DFT). Then, a possible catalytic mechanism for photocatalytic CO2 and CH4 conversion is proposed based on DFT calculations and experimental results. This work provides a new technical route for the rapid conversion of CO2 and CH4 at room temperature, as well as a new research concept for achieving carbon neutrality.