Regulating N Species in N-Doped Carbon Electro-Catalysts for High-Efficiency Synthesis of Hydrogen Peroxide in Simulated Seawater

Abstract

Electrochemical oxygen reduction reaction (ORR) is an attractive and alternative route for the on-site production of hydrogen peroxide (H₂ O₂ ). The electrochemical synthesis of H₂ O₂ in neutral electrolyte is in early studying stage and promising in ocean-energy application. Herein, N-doped carbon materials (N-C_x ) with different N types are prepared through the pyrolysis of zeolitic imidazolate frameworks. The N-C_x catalysts, especially N-C₈₀₀ , exhibit an attracting 2e^- ORR catalytic activity, corresponding to a high H₂ O₂ selectivity (≈95%) and preferable stability in 0.5 m NaCl solution. Additionally, the N-C₈₀₀ possesses an attractive H₂ O₂ production amount up to 631.2 mmol g^-1 h^-1 and high Faraday efficiency (79.8%) in H-type cell. The remarkable 2e^- ORR electrocatalytic performance of N-C_x catalysts is associated with the N species and N content in the materials. Density functional theory calculations suggest carbon atoms adjacent to graphitic N are the main catalytic sites and exhibit a smaller activation energy, which are more responsible than those in pyridinic N and pyrrolic N doped carbon materials. Furthermore, the N-C₈₀₀ catalyst demonstrates an effective antibacterial performance for marine bacteria in simulated seawater. This work provides a new insight for electro-generation of H₂ O₂ in neutral electrolyte and triggers a great promise in ocean-energy application.

Keywords: N-doped carbon; antibacterial; hydrogen peroxide; oxygen reduction reaction; simulated seawater.