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

Abstract

The development of efficient and highly selective photocatalysts is a key point for the photocatalytic conversion of CO2. In this paper, a composite catalyst UiO-66-NH2/Ce(HCOO)3 (simplified to UNH/Ce(HCOO)3) was fabricated by one pot method with CeCO3OH 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 CH4 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 CH4 selectivity of 71.9 %, and the Relectron reached 286.46 μmol g−1 h−1. The UV–vis diffuse reflection spectra and photoelectrochemical tests results confirmed that the improved photocatalytic CO2 reduction performance and high CH4 selectivity could be attributed to the formation of the type-Ⅱheterojunction of UNH/Ce(HCOO)3 with abundant Ce3+, 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 CO2 to CH4. 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.