CO 2 Enrichment Boosts Highly Selective Infrared-Light-Driven CO 2 Conversion to CH 4 By UiO-66/Co 9 S 8 Photocatalyst.

Photocatalytic CO 2 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 low-energy IR light. To meet this challenge, UiO-66/Co 9 S 8 composite is designed to couple the advantages of metallic photocatalysts and porous CO 2 adsorbers for IR-light-driven CO 2 -to-CH 4 conversion. The metallic nature of Co 9 S 8 endows UiO-66/Co 9 S 8 with exceptional IR light absorption, while UiO-66 dramatically enhances its CO 2 affinity. Notably, finite-element method simulations reveal the porous structure of UiO-66 enriches local CO 2 concentration around Co 9 S 8 . As a result, Co 9 S 8 or UiO-66 alone doesn't show observable IR-light photocatalytic activity, whereas UiO-66/Co 9 S 8 reveals exceptional activity. The CH 4 evolution rate over UiO-66/Co 9 S 8 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 XAFS spectra verify the presence of two distinct Co sites and confirm the existence of metallic Co-Co bond in Co 9 S 8 . Energy diagrams analysis and fs-TA spectra manifest that CO 2 reduction mainly occurs on Co 9 S 8 for UiO-66/Co 9 S 8 , while DFT 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 towards CH 4 . This article is protected by copyright. All rights reserved.