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

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.