Constructing Co and Zn Atomic Pairs in Core-Shell Co3s4/Nc@Zns/Nc Derived from Mof-on-Mof Nanostructures for Enhanced Photocatalytic Co2 Reduction to C2h4

Herein, a core-shell structured Co3S4/NC@ZnS/NC heterojunction has been constructed via elaborately synthesizing metal-organic framework (MOF)-on-MOF precursors (ZIF-67@ZIF-8) and following controlled carbonization-sulfidation processes. The developed Co3S4/NC@ZnS/NC achieves higher performances for CO2 photoreduction with water vapor towards CO (28.44 μmol g−1 h−1), CH4 (1.93 μmol g−1 h−1) and C2H4 (12.33 μmol g−1 h−1) in a continuous-flow condition under visible-light irradiation. 13CO2 isotope tracer analysis verifies that CO, CH4 and C2H4 originate from the carbon source of CO2. Experiment and DFT calculations confirm that constructing an electron transport layer (ZnS/NC) in Co3S4/NC@ZnS/NC can contribute to a feasible channel for the enhanced separation and transfer of charge carriers. In heterojunction, non-bonding Co and Zn atomic pairs as adsorption sites synergistically participate in the CO2 activation through the unique electron transport channel and acquire the lower energy barriers of COOH* formation. Moreover, in situ DRIFTS reveals the key intermediates and possible conversion pathways.