Summary: Impartial electrosynthesis of H2O2 by way of 2e- ORR is enticing for a lot of functions, however the low exercise and excessive value of electrocatalysts have grow to be essential constraints. Due to this fact, creating low cost and environment friendly electrocatalysts for 2e- ORR is critical. Herein, transition metallic single atoms (TM SA) embedded in g-C3N4 nanosheets (CNNS) have been obtained. The introduction of TM SA will increase the N-C=N content material and reduces the C-C/C=C content material in CNNS, which contributes to the elevated selectivity of 2e- ORR of TM SA/CNNS. As well as, TM SA is the primary purpose for the improved exercise of 2e- ORR. Primarily based on the outcomes by changing a sequence of TM SA, Ni0.10 SA/CNNS with optimum N-C=N content material displays the perfect selectivity (~98%) and highest yield of H2O2 (~503 mmol gcat-1 h-1), which is ~14.6 instances increased than that of CNNS (~34.4 mmol gcat-1 h-1). And different TM SA/CNNS additionally displays excessive exercise and selectivity. This examine demonstrates the power of TM SA to modulate the selectivity and exercise of CNNS, making it a promising candidate for 2e- ORR and offering extra reference concepts for the preparation of H2O2.