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

Abstract Photocatalytic 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.