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

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Co-catalysts decorations provide unique opportunities in promoting the photocatalytic water splitting performance of graphite carbon nitride (g-C 3 N 4 ) system, while mechanistic understanding of this complex catalytic network remains elusive. Here, taking the single-atom-based photocatalysts (M 1 -g-C 3 N 4 ) as an unprecedented simplified model system, we theoretically tracked the photocatalytic kinetics for a comprehensive understanding of the photocatalytic process and affords the descriptor α S1-T1/ α T1-S0 (ratio of the extent of S 1 -T 1 and T 1 -S 0 state mixing) and Δ G H* (hydrogen adsorption free energy) for rational screening of photocatalysts. The targeted Fe 1 -g-C 3 N 4 yielded an excellent H 2 evolution rate (ca. 3.2 mmol g cat −1 h −1 under full arc), two order of magnitude improvement relative to pristine g-C 3 N 4 counterpart and also outperforms other representative 3 d -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/photochemical aspects. This work presents a comprehensive understanding of the essential role of isolated atomic sites in the photocatalytic process based on a combination of theoretical with experimental studies. The photophysical, photochemical descriptors of α S1-T1/ α T1-S0 (ratio of the extent of S 1 -T 1 and T 1 -S 0 state mixing) and Δ G H* (hydrogen adsorption free energy) are proposed for rational screening of photocatalysts. • The photocatalytic courses of a prototype single-atom-based photocatalysts (M 1 -g-C 3 N 4 ) were tracked based on a combination of DFT calculations with experimental studies. • General descriptors α S1-T1/ α T1-S0 (ratio of the extent of S 1 -T 1 and T 1 -S 0 state mixing) and Δ G H* (hydrogen adsorption free energy) were proposed for rational screening of photocatalysts. • The targeted Fe 1 -g-C 3 N 4 yielded excellent H 2 evolution rate (ca. 3.2 mmol g cat −1 h −1 under full arc), two order of magnitude improvement relative to pristine g-C 3 N 4 and also outperforms other representative 3 d -transition-metal-based photocatalysts.