Unveiling the charge migration-induced surface reconstruction of Cu2MoS4 catalyst for boosted CO2 reduction into olefiant gas

Understanding the charge dynamic behavior of the catalyst is crucial to unravel the underlying mechanism for photocatalytic CO2 reduction to C2+ products. However, the structure–activity relationships are not intuitive because of the dynamic evolution of electronic and atomic structures for catalysts under the excitation state. Herein, modeling on layered Cu2MoS4 nanosheets, we for the first time observe charge migration-induced evolution of electronic and atomic structure on Cu2MoS4 catalyst during the CO2 reduction process by combining synchronous-illumination X-ray photoelectron spectroscopy (SI-XPS) with X-ray diffraction (SI-XRD). During the dissociation of CO2 molecules as well as the charge migration process under the visible light irradiation condition, the surface S atoms return back to the lattice phase, leading to the valence-state normalization of Cu, Mo and S atoms and the increases of the interlayer lattice spacing. By virtue of the above unique characteristic changes, Cu2MoS4 nanosheets exhibit excellent activity enhancement (8.7 μmol g−1 h−1) for CO2 reduction to C2H4 under the visible light irradiation in comparison with the trace amount of Cu-doped MoS2 and pure MoS2.