Transition metal single atom-optimized g-C 3 N 4 for the highly selective electrosynthesis of H 2 O 2 under neutral electrolytes.

Neutral electrosynthesis of H 2 O 2 via the 2e - ORR is attractive for numerous applications, but the low activity and high cost of electrocatalysts have become important constraints. Therefore, the development of cheap and efficient electrocatalysts for the 2e - ORR is necessary. Herein, we report the embedding of transition metal single atoms (TM SAs) in g-C 3 N 4 nanosheets (CNNS). The introduction of TM SAs increases the N-CN content and reduces the C-C/CC content in CNNS, which contributes to the increased selectivity of TM SA/CNNS for the 2e - ORR. TM SA is the main reason for the enhanced activity of the 2e - ORR. Based on the results obtained by replacing a series of TM SA, the Ni 0.10 SA/CNNS with optimal N-CN content exhibited the best selectivity (∼98%) and highest yield of H 2 O 2 (∼503 mmol g cat -1 h -1 ), which is ∼14.6 times higher than that of CNNS (∼34.4 mmol g cat -1 h -1 ). Other TM SA/CNNS also exhibited high activity and selectivity. This study demonstrates the ability of TM SA to modulate the selectivity and activity of CNNS, making it a promising candidate for the 2e - ORR and providing more reference ideas for the preparation of H 2 O 2 .