Electronically neighbored redox active sites on polymeric carbon nitride for efficient photocatalysis pairing selective CO2 reduction and 5-hydroxymethylfurfural oxidation

Cooperatively integrating CO2 reduction reaction (CO2RR) with selective organic oxidation reaction presents an attractive opportunity to simultaneously utilize photogenerated holes and electrons to realize the production of carbon-based fuels and value-added chemicals. Herein, electronically neighbored redox active sites of Cu single atoms (Cu SAs) and ultrasmall oxygen-deficient cobalt oxide (CoOV) clusters are loaded onto polymeric carbon nitride (CN) for photocatalytic CO2RR coupling with 5-Hydroxymethylfurfural oxidation reaction (HMFOR). The obtained CoOV-CuCN photocatalyst achieves a high performance for CO and 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) production at the rate of 49.6 and 34.7 μmol g−1 h−1, affording the high selectivity of 91.6% and 81.6%, respectively. Spectral investigations and theoretical calculations reveal that the CoOV sites would upshift the d-band center of neighboring Cu SAs towards the Fermi level, which stabilizes the *COOH intermediate on Cu SAs and thereby promotes the CO2-to-CO conversion; moreover, the oxygen vacancies (OV) could trigger the charge redistribution at CoOV sites for efficient HMF adsorption and oxidation for HMFCA production. This work provides a reliable strategy for the rational design of surface active sites with modulated geometric and electronic configurations for paired redox photocatalysis and also paves an alternative way to promote the economic benefits and the technology upgrading of solar energy conversion and utilization.