W18O49/MnWO4 heterojunction for highly efficient photocatalytic reduction of CO2 under full spectrum light

Solar-energy-driven CO2 reduction for chemical reagents production, such as CH3OH, CH4 and CO, has tremendous potential for carbon neutrality in the energy industries. However, the low reduction efficiency limits its applicability. Herein, W18O49/MnWO4 (WMn) heterojunctions were prepared via one-step in-situ solvothermal process. Through this method, W18O49 tightly combined with the surface of MnWO4 nanofibers to form nanoflower heterojunction. It was found that under full spectrum light irradiation for 4 h, the yields of photoreduction of CO2 to CO, CH4 and CH3OH by 3-1 WMn heterojunction were 61.74, 71.30 and 18.98 μmol/g, respectively, which were 2.4, 1.8 and 1.1 times that of pristine W18O49, and ca.20 times that of pristine MnWO4 towards CO production. Furthermore, even in the air atmosphere, the WMn heterojunction still performed excellent photocatalytic performance. Systematic investigations demonstrated that the catalytic performance of WMn heterojunction was improved by superior light utilization and more efficient photo-generated carrier separation and migration as compared with W18O49 and MnWO4. Meanwhile, the intermediate products of the photocatalytic CO2 reduction process were also studied in detail by in-situ FTIR. Therefore, this study provides a new way for designing high efficiency of heterojunction for CO2 reduction.