Facile fabrication of well-designed 2D/2D porous g-C3N4–GO nanocomposite for photocatalytic methane reforming (DRM) with CO2 towards enhanced syngas production under visible light

Abstract

Well-designed 2D/2D graphene oxide modified polymeric graphitic carbon nitride nanosheets composite (g-C3N4-GO) for photocatalytic dry reforming (DRM) of methane via CO2 into syngas (CO, H2) under visible light system has been investigated. The metal-free nanocomposite was synthesized through a facile thermal sonochemical-assisted approach. The 0.5 wt % GO/g-C3N4 composite exhibited the highest CO production of 399 µmol g-1 after 4 h irradiation, which represents more than 5 times enhancement compared to pure g-C3N4 (78.1 µmol g-1). However, by varying the GO content, it was observed that the maximum H2 amount evolved with a GO content of 0.25 wt %. This study reveals the role of GO nanosheets as electronic conductive channels for efficient transfer and separation of photo-generated electron-hole pairs (e-/h+) and hence, improving the DRM process for syngas production. The 0.5 % GO/ g-C3N4-GO composite was also tested under various parameters of CO2/CH4 feed ratios, reducing agents, operating pressures and photocatalyst loading. The results revealed the superiority of photocatalytic DRM process over the steam reforming (SRM) and bi-reforming (BRM) processes with an equal CO2/CH4 feed ratio. By increasing the pressure, the production of CO and H2 was increased due to more attachment of reactants to catalyst surface, whereas increased catalyst loading had a negative effect on the production. This research provides a new promising pathway for the construction of easy-prepared and metal-free nanocomposites that would be beneficial for further investigations of selective, single-step applications of photocatalytic CO2 DRM with CH4 into a syngas and other valuable solar fuels.