Constructing asymmetric unsaturated copper coordination in Zinc(II)/Copper(I, II)-based metal-organic framework toward productive CO2-to-methanol photocatalytic conversion from CO2-capturing solution

Abstract

Copper-based catalysts show potential advantages with respect to applications in CO2 photoreduction into valuable chemicals. However, there remain great challenges to reduce band gap energy and inhibit recombination of photogenerated electron-hole pairs. Herein, we report a metal-organic framework, Zn(II)/Cu(I, II)-BTC synthesized via facile one-pot solvothermal method. Asymmetric unsaturated tetrahedral copper coordination was verified by multiple characterizations including extended X-ray absorption fine structure and electron paramagnetic resonance analyses coupled with DFT calculations. Promoted separation and transfer of photogenerated electrons and largely inhibited recombination of electron-hole pairs contribute to a productive methanol yield of 4470 μmol·g−1·h−1, which is 107% higher than that over the parent Cu-BTC. In situ diffuse reflectance infrared Fourier transform spectroscopy measurement and DFT calculation were combined to elucidate the underlying mechanism. This study provides insights into effectively tuning separation and transfer of charge within copper-based photocatalysts and highlights the role of copper coordination in valence engineering.