CO2 Enrichment Boosts Highly Selective Infrared‐Light‐Driven CO2 Conversion to CH4 by UiO‐66/Co9S8 Photocatalyst

Abstract

AbstractPhotocatalytic CO2 reduction to high‐value chemicals is an attractive approach to mitigate climate change, but it remains a great challenge to produce a specific product selectively by IR light. Hence, UiO‐66/Co9S8 composite is designed to couple the advantages of metallic photocatalysts and porous CO2 adsorbers for IR‐light‐driven CO2‐to‐CH4 conversion. The metallic nature of Co9S8 endows UiO‐66/Co9S8 with exceptional IR light absorption, while UiO‐66 dramatically enhances its local CO2 concentration, revealed by finite‐element method simulations. As a result, Co9S8 or UiO‐66 alone does not show observable IR‐light photocatalytic activity, whereas UiO‐66/Co9S8 exhibits exceptional activity. The CH4 evolution rate over UiO‐66/Co9S8 reaches 25.7 µmol g−1 h−1 with ca.100% selectivity under IR light irradiation, outperforming most reported catalysts under similar reaction conditions. The X‐ray absorption fine structure spectroscopy spectra verify the presence of two distinct Co sites and confirm the existence of metallic Co─Co bond in Co9S8. Energy diagrams analysis and transient absorption spectra manifest that CO2 reduction mainly occurs on Co9S8 for UiO‐66/Co9S8, while density functional theory calculations demonstrate that high‐electron‐density Co1 sites are the key active sites, possessing lower energy barriers for further protonation of *CO, leading to the ultra‐high selectivity toward CH4.