Subnano Polyhydroxylated C₆₀ and Co-oxo Clusters Enable Accelerated Electron Kinetics for CO₂ Photoreduction in Pure Water

Accelerating the electron kinetics is critical for enhancing the photocatalytic performance of CO2 conversion. Herein, polyhydroxylated C60 (C60OH, ∼1.8 nm) was molecularly decorated on boron-doped carbon nitride (BCN) nanosheets via a hydrogen-bonding assembly process. Subsequently, subnano Co-oxo clusters (∼0.4 nm) were precisely deposited on the BCN counterpart using a photohole-induced approach. The optimized nanocomposite photocatalyst, featuring spatially separated dual subnano modifiers, exhibits a 10-fold CO2 conversion rate of that for BCN in pure water and nearly 100% selectivity toward CO by completely inhibiting H2 evolution. Notably, the apparent quantum yield reaches 3.51% (405 nm), surpassing that of representative cocatalyst-involved (boron-doped) carbon nitride-based photocatalysts under similar conditions. Femtosecond-transient absorption spectra reveal that C60OH and Co-oxo clusters can rapidly extract electrons and holes, respectively, with balanced transfer rates. Moreover, the hydroxyl groups of C60OH can serve as CO2 adsorption and catalytic sites, whereas Co-oxo clusters are capable of catalyzing water oxidation. The synergy between dual subnano modifiers effectively improves the electron kinetics, resulting in an electron transfer efficiency of 41.1% determined by in situ microsecond-transient absorption spectroscopy. This work provides a rational design strategy for developing advanced photocatalysts by modulating electron kinetics.