Dual-Engineering of Porous Structure and Carbon Edge Enables Highly Selective H2O2 Electrosynthesis

Edge engineering has emerged as a powerful strategy to activate inert carbon surfaces, and thus achieve a notable enhanced electrocatalytic activity. However, the rational manipulation of carbon edges to achieve enhanced catalytic performance remains a formidable challenge, primarily hindered by immature synthesis methods and the obscured understanding of the structure-activity relationship. Herein, an organic-inorganic hybrid co-assembly strategy is used to fabricate a series of mesoporous carbon nanofibers (MCNFs) with controllable edge site densities and the impact of edge population on electrochemical oxygen reduction reaction (ORR) pathways is investigated. The optimized MCNFs catalyst exhibits a remarkable 2e(-) ORR performance, as evidenced by a high H2O2 selectivity (>90%) across a wide potential window of 0.6 V and a large cathodic current density of -3.0 mA cm(-2) (at 0.2 V vs. reversible hydrogen electrode). Strikingly, the density of carbon edge sites can be changed to tune the ORR activity and selectivity. Experimental validation and density functional theory calculations confirm that the presence of edge defects can optimize the adsorption strength of *OOH intermediates and balance the selectivity and activity of the 2e(-) ORR process. This study provides a new path to achieve high ORR activity and 2e(-) selectivity in carbon-based electrocatalysts.

Automated summary

An organic-inorganic hybrid co-assembly strategy is used to fabricate mesoporous carbon nanofibers with controllable edge site densities, and the impact of edge population on electrochemical oxygen reduction reaction pathways is investigated. The optimized catalyst exhibits remarkable 2e(-) ORR performance, and the density of carbon edge sites can be changed to tune the ORR activity and selectivity.