Enriched Ti3+ in TiONC electrocatalyst for efficient H2O2 generation via 2-electron oxygen reduction reaction

Abstract

The 2-electron electrochemical oxygen reduction reaction (ORR) is considered a viable method for synthesizing H2O2 because of its efficiency and environmental friendliness. However, conventional catalysts for this reaction predominantly rely on high-cost metals and require complex preparation procedures. Herein, we synthesized an electrocatalyst containing TiN and N-doped carbon via the pyrolysis of melamine and MIL125(Ti)–NH2. The effects of melamine and pyrolysis temperature on the chemical composition and defect site formation were investigated. Importantly, the obtained results suggest that the generated Ti3+ sites are more important in enhancing the performance of the 2-electron ORR, surpassing defective carbon and oxygen functional groups. In particular, the resulting TiONC-MA-1000 catalyst prepared through pyrolysis at 1,000 °C contained abundant Ti3+ sites, resulting in high 2-electron ORR activity with a molar selectivity exceeding 91 % and high stability over a 12 h testing period. The electrochemical H2O2 generation experiments conducted in an H-cell configuration employing TiONC-MA-1000 as the electrocatalyst yielded 6.99 mol⋅gcatalyst−1⋅h−1 H2O2. Therefore, the present study proposes a facile approach for fabricating highly active electrocatalysts suitable for large-scale H2O2 production.