Fabrication of UiO-66-NH2/Ce(HCOO)3 heterojunction with enhanced photocatalytic reduction of CO2 to CH4

The development of efficient and highly selective photocatalysts is a key point for the photocatalytic conversion of CO 2 . In this paper, a composite catalyst UiO-66-NH 2 /Ce(HCOO) 3 (simplified to UNH/Ce(HCOO) 3 ) was fabricated by one pot method with CeCO 3 OH as the precursor. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) characterizations results confirmed that UNH was dispersed on the surface of Ce(HCOO) 3 and strongly interacted with it via Ce-N bond. The yield of CH 4 on the optimal UNH/Ce(HCOO) 3 catalyst reached 3 times of that on pristine UNH, up to 128.81 μmol g −1 , with the CH 4 selectivity of 71.9 %, and the R electron reached 286.46 μmol g −1 h −1 . The UV–vis diffuse reflection spectra and photoelectrochemical tests results confirmed that the improved photocatalytic CO 2 reduction performance and high CH 4 selectivity could be attributed to the formation of the type-Ⅱheterojunction of UNH/Ce(HCOO) 3 with abundant Ce 3+ , which expanded the visible light absorption range, accelerated the separation and transfer rates of photogenerated charges, and thus efficiently promoted the multi-electron reduction reaction of CO 2 to CH 4 . In addition, the reaction temperature affected profoundly the cycle performance of the catalyst. The results presented here illustrated the possibility for improving the stability of UNH/Ce(HCOO) 3 -1.80 by decreasing reaction temperature.