The cooperative performance of iodo and copper in a Zr-based UiO-67 metal-organic framework for highly selective photocatalytic CO2 reduction to methanol

Abstract

Photocatalytic CO2 reduction (PCR) to fuels using metal-organic frameworks (MOFs) offers promising solutions for both enhancing energy supply and mitigating global warming. However, research addressing the selectivity towards MeOH production, the role of CO2 uptake in productivity, and the identification of intermediates remains limited. Herein, we present an iodo/copper functionalization strategy for the Zr-based UiO-67 MOF. The resulting bifunctional Cu/I2-Zr-BPDC/BPyDC exhibited remarkable selectivity in light-driven CO2 reduction to MeOH, revealing the first investigation of halogen bonding's effect on PCR. Crucially, Cu/I2-Zr-BPDC/BPyDC surpassed not only pristine Zr-BPyDC, I2-Zr-BPDC, and Cu-Zr-BPyDC, but also boasted the best catalytic performance among reported MOFs. Furthermore, Cu/I2-Zr-BPDC/BPyDC demonstrated a CO2 uptake capacity of 48.6 mg g−1, 1.7 times greater than non-modified Zr-BPyDC, suggesting a direct correlation between CO2 adsorption efficiency and CO2 conversion. In addition to assigning CuII ↔ CuI catalytic cycle, collaborative performance of I and Cu functions in CO2 activation was traced by infrared spectra that elucidate the CI…OCO interaction and Cu…CO2/CuCO2H complex formation. This work provides valuable insights for engineering selective and high-performance PCR catalyst through the rational incorporation of functionalities within MOFs.