Designing Highly Active Nanoporous Carbon Electrocatalysts for H2O2 Production Via Active Site Elucidation

Abstract

Fossil fuel-based hydrocarbon economy has invoked a serious climate change due to ever-increasing emission of CO2. In this regard, electrosynthesis has emerged as a promising route that enables the clean and continuous production of chemicals and fuels.[1] Electrochemical production of hydrogen peroxide (H2O2) via the two-electron (2e−) oxygen reduction reaction (ORR) can serve as a promising alternative for the currently prevailing anthraquinone process [1,2]. However, improving H2O2 selectivity remains one of important challenges in electrochemical H2O2 production because 2e− ORR competes with 4e− ORR, further reduction of H2O2 (2e−+2e− ORR), and H2O2 chemical disproportionation. Carbon nanomaterials have demonstrated promising performance for H2O2 production as low-cost electrocatalysts [3–5], however understanding of key structural factors and active sites is still lacking. In this work, we have prepared nanoporous carbon-based model catalysts and conducted a systematic study to identify the active oxygen functionality and carbon structure factor [6]. We have found that the carboxyl (O−C=O) groups located at the graphitic edge carbons are the major active sites for the electrosynthesis of H2O2 (Figure (a)). The best-performing carbon catalyst (O-GOMC-5.5) with abundant active oxygenated graphitic edge carbons exhibited the highest H2O2 production activity among the reported carbon-based catalysts (Figure (b)) and excellent long-term stability (168 h) with almost 100% of H2O2 faradaic efficiency. Figure 1