Chemical Bonding of g-C3N4/UiO-66(Zr/Ce) from Zr and Ce Single Atoms for Efficient Photocatalytic Reduction of CO2 under Visible Light

Abstract

The most promising approach to mitigating the greenhouse effect and tackling the energy crisis is to convert carbon dioxide into valuable liquid fuels through artificial photosynthesis. Nevertheless, most photocatalysts have poor product selectivity, low catalytic performance, and poor cycling stability. Herein, we synthesized novel UiO-66(Zr/Ce) nanosheets bonding on g-C3N4 [g-C3N4/UiO-66(Zr/Ce)] by an in situ method using single atoms of Zr and Ce as metal sources, and the g-C3N4 and UiO-66(Zr/Ce) are linked via N–Zr/Ce–O bonds on the g-C3N4/UiO-66 interface. Chemical bonds and close contact between UiO-66(Zr/Ce) with a two-dimensional structure and g-C3N4 accelerate the transmission of electrons and significantly suppresses the quenching of photogenerated carriers. Furthermore, the doping of Ce in g-C3N4/UiO-66(Zr/Ce) concentrates the photogenerated electrons around the Ce atoms, making the multielectron CO2 reduction reaction more favorable. Without adding any sacrificial agent, the g-C3N4/UiO-66(Zr/Ce) shows efficient reduction of CO2 to CH3OH (54.71 μmol h–1 g–1) and C2H5OH (38.10 μmol h–1 g–1). Moreover, the TOF value of the composite catalyst is 28 times that of bulk UiO-66(Zr/Ce). It exhibits excellent stability thanks to the strong coordination bonds of the composite catalyst. After 12 cycles, the photocatalytic performance does not decrease.