Direct Z-Scheme WO3/Graphitic Carbon Nitride Nanocomposites for the Photoreduction of CO2

In this article, we successfully prepared the WO 3 /g-C 3 N 4 (WO/CN) heterojunction photocatalyst with high photocatalytic CO 2 reduction performance by the simple impregnation–calcination process. Transmission electron microscopy (TEM) analysis shows that the WO 3 nanoparticles (WO 3 NPs) are successfully attached to the g-C 3 N 4 nanosheets (CN). UV–vis reflectance spectrum (UV–vis DRS), photoluminescence spectrum (PL), and photoelectrochemical (PEC) results confirm that the building of a WO/CN heterojunction is beneficial to the transfer and separation processes of the photogenerated carriers in the photocatalysts. The photoreduction performances of the obtained samples are indicated by the photocatalytic CO 2 reduction process under UV and visible light irradiation. These experiments prove that the 10-WO/CN photocatalyst has the best photoreduction performance compared to other obtained photocatalysts. The yields of CO and CH 4 in the presence of the 10-WO/CN photocatalyst are 8.9 and 47.7 times larger than those of pure CN under UV irradiation. For the irradiation of visible light, the yield rates of CO and CH 4 over 10-WO/CN are 8.6 and 7.5 times greater than those of the CN. On the basis of these photocatalytic results and electron spin resonance (ESR) results, the possible direct Z-scheme electron transfer mechanism for 10-WO/CN with the improved photoreduction CO 2 activity has been discussed.