Cobalt single atom induced catalytic active site shift in carbon-doped BN for efficient photodriven CO2 reduction

We present a strategy for single-atom induced catalytic site transfer. The catalyst Co/C-BN with new active sites exhibits excellent photocatalytic activity and selectivity of CO in pure water. [Display omitted] •Cobalt single atom induces catalytic active site shift from CN3 to CB3.•The introduced Co atom changes the spin density of the neighboring catalytic site.•Co/C-BN exhibits excellent photocatalytic activity without sacrificial reagents.•The possible photocatalytic reaction mechanisms are revealed in depth. Active site tuning in catalyst design is the key to improving the catalyst performance. Herein, we introduce single cobalt atoms into carbon-doped boron nitride (C-BN) and find, to our surprise, that the photocatalytic CO2 reduction site of C-BN shifts from CN3 to CB3. The catalyst Co/C-BN with new active sites exhibits excellent photocatalytic activity and selectivity of CO without adding sacrificial reagents, while the side reaction of hydrogen evolution is significantly inhibited. Theoretical calculations show that the introduced Co atom changes the spin density of the neighboring catalytic site, thus regulating the adsorption energy of the catalytic site for active intermediates (COOH*). Compared with CN3 site, CB3 in Co/C-BN shows superiority in CO* formation elementary step for the conversion of CO2 to CO, and inhibits the generation of adsorbed H2 in the competitive water-splitting reaction. This work provides valuable insights into the design of highly efficient catalysts in the future.