Modulating d-band center of Co3O4 monolith by defects to boost CO2 photoreduction: from charge transport limitation to surface reaction optimization

Developing efficient monolith catalysts for photocatalytic CO 2 reduction remains fundamentally challenging due to their inherently sluggish charge transfer. Herein, we report a Co 3 O 4 catalyst with serious agglomeration and meanwhile rich in oxygen vacancies (V O -r-Co 3 O 4 ), which achieves an unexpected superior photocatalytic CO evolution rate of 19.56 mmol h −1  g −1 . Experimental results and density functional theory (DFT) calculations reveal that V O play a crucial role in optimizing the CO 2 reduction pathway. Specifically, the abundant V O create a low-coordination environment around Co atoms, substantially weakening the Co O orbital hybridization. This directly induces a significant downshift of the Co 3 d -band center, effectively alleviating the overbinding of reaction intermediates. Consequently, the energy barriers for both the rate-determining *COOH formation and CO desorption are substantially reduced. This work highlights the importance of local electronic modulation in overcoming the charge transport limitations of monolith catalysts, offering a cost-effective strategy to revitalize such materials for solar energy conversion. Download: Download high-res image (146KB) Download: Download full-size image