Z-scheme heterojunctions composed of 3D graphene aerogel/g-C3N4 nanosheets/porous ZnO nanospheres for the efficient photocatalytic reduction of CO2 with H2O under visible light irradiation

Abstract

In this paper, a Z-scheme nanosheet/porous nanosphere (NSP) heterojunction system composed of g-C 3 N 4 (CN) and ZnO anchored on 3D graphene aerogels (GAs) was synthesized using a facile process. According to the results, the CN/ZnO/GA-7 showed a remarkable CO production rate of 33.87 μmol·g −1 ·h −1 under visible light irradiation, 25, 21 and 3 times higher than those of ZnO, g-C 3 N 4 , and CN/ZnO, respectively. Furthermore, this rate far exceeded the reported conventional photocatalytic reduction efficiency of CO2. Moreover, the CN/ZnO/GA exhibited exceptional stability and potential for commercial applications. These NSP heterojunctions provided a strong interfacial interaction and brought about abundant active sites and coupling large interfaces. The unique structure promoted the transport and separation of photogenerated carriers and facilitated effective mass transport and light absorption. Additionally, a multi-electron series reduction mechanism based on Z-scheme photocatalytic system was proposed to explain the CO 2 reduction over this material. Taken together, this work demonstrated a promising photocatalytic hybrid system with 3D aerogel-based Z-scheme NSP heterojunctions for efficient and stable CO 2 reduction. • 3D porous hybrid CN/ZnO/GA in the Z-scheme approach were firstly successfully synthesized by a using a facile process. • CN/ZnO/GA showed remarkable photocatalytic CO 2 recduction performance with CO yield of 33.87 mmol·g -1 ·h -1 under water vapour. • Heterojunctions can effectively accelerate the transfer and separation of photo-induced carriers and enhance the active site.