2D–1D-2D multi-interfacial-electron transfer scheme enhanced g-C3N4/MWNTs/rGO hybrid composite for accelerating CO2 photoreduction

Abstract

Highly-efficient supply of the photogenerated carriers is a necessary condition for excellent photocatalytic reactions. In this paper, 2D–1D-2D multi-interfacial electron transfer scheme enhanced g-C3N4/MWNTs/rGO (CMR) were prepared for CO2 photoreduction. CO2 photoreduction tests showed that the CO and CH4 yields with CMR-3 as the catalyst were about 699.69 μmol/g and 479.47 μmol/g under the UV-Vis light irradiation, which were about 21.9 and 59.3 times higher than that of pure g-C3N4. Furthermore, the obtained CMR-3 also exhibited excellent CO2 photoreduction performance under the visible light irradiation, and the obtained CO/CH4 ratio of g-C3N4 and CMR-3 were about 13.08 and 73.54, which confirmed that the CO selectivity was greatly enhanced after the co-modification of P-MWNTs and rGO. Photo-electrochemistry tests confirmed that the modification of P-MWNTs and rGO can efficiently speed up the separation efficiency of photogenerated carriers inside of g-C3N4. Besides, Zeta potential, water contact angle, and static experiment proved the co-modification of P-MWNTs and rGO could improve the dispersion of g-C3N4 in water environment. The UPS and UV-Vis DRS further confirmed the built-in electric fields at the interfaces of g-C3N4/P-MWNTs, P-MWNTs/rGO and g-C3N4/rGO, which were great beneficial for the CO2 photoreduction reaction. Finally, the multi-interfacial electron transfer scheme enhanced photoreduction process was provided.