Insights into atomically dispersed reactive centers on g-C3N4 photocatalysts for water splitting

Co-catalysts decorations provide unique opportunity in promoting the photocatalytic water splitting performance of graphite carbon nitride (g-C3N4) system, while mechanistic understanding of this complex catalytic network remains elusive. Here, taking the single-atom-based photocatalysts (M1-g-C3N4) as an unprecedented simplified model system, we theoretically tracked the photocatalytic kinetics for a comprehensive understanding of the photocatalytic process and afforded the descriptor αS1-T1/αT1-S0 (ratio of the extent of S1-T1 and T1-S0 state mixing) and ΔGH∗ (hydrogen adsorpti on free energy) for rational screening of photocatalysts. The targeted Fe1-g-C3N4 yields an excellent H2 evolution rate (ca. 3.2 ⋅mmol·gcat−1·h−1 under full arc), two order of magnitude improvement relative to pristine g-C3N4 counterpart and also outperforms other representative 3d-transition-metal-based photocatalysts. This work presents a comprehensive understanding of the essential role of isolated atomic sites in the photocatalytic course and sheds light on the design of photocatalysts from both photophysical and photochemical aspects.