Hydrogenated Pyridine-Pyrrole Nitrogen-Doped Carbon for High-Efficiency Electrosynthesis of Hydrogen Peroxide in NaCl Electrolyte

Developing metal-free carbon catalysts is critical to achieve the electrosynthesis of hydrogen peroxide (H2O2) via two-electron oxygen reduction reaction (2e(-) ORR) using seawater as electrolyte. Herein, N-rich doped carbon (NC) is synthesized by directly pyrolyzing guanine as both N and C sources, which can facilitate the formation of ultrahigh-N dopant (up to 33.89 at.%), and their ratios. The NC obtained at 700 degrees C with hydrogenated pyridine-N and pyrrole-N (3:2) dopants exhibits a superior selectivity of H2O2 (up to 96%), high mass activity of 545.5 A g(-1) at 0.2 V versus RHE and stable production of H2O2 with 16.8 molg(cat)(-1).h(-1) in 0.5 M NaCl. In situ Fourier transform infrared spectrum analysis proves that hydrogenated pyridine-N and pyrrole-N dopants play a critical role in constructing metal-free active sites for the synthesis of H2O2. Meanwhile, theoretical calculations further reveal that compared to non-hydrogenated N dopants, hydrogenated pyridine and pyrrole N can tune the projected density of states of 2p(z) orbitals of their adjacent carbon atoms approaching Fermi Level, enhancing *OOH to H2O2 through 2e(-) ORR rather than H2O via 4e(-) ORR. This work provides new insights for developing metal-free catalysts for efficient electrosynthesis of H2O2 using seawater resources as promising electrolytes.