Enhanced on-site hydrogen peroxide electrosynthesis by a selectively carboxylated N-doped graphene catalyst

Abstract

Practical-scale on-site production of hydrogen peroxide (H2O2) via two-electron (2e(-)) oxygen reduction reaction (ORR) relies on efficient, robust, and selective electrocatalysts. Among them, carbon-based materials are cheap, abundant, durable, and their surface properties can be tuned to favor the 2e(-) ORR pathways, resulting in higher efficiency and facilitating possible scale-up towards commercially appealing levels. Here, we demonstrate that the selective installment of carboxyl groups on the surface of N-doped graphene yielding a material named graphene acid (N-GA) promotes the catalytic 2e(-) ORR, achieving a H2O2 faradaic efficiency (FE) as high as 70 % in acidic media (pH=0.96) and a H2O2 productivity in long term bulk electrolysis that could reach 107.8 mmol g(catalyst)(-1) h(-1) under optimized conditions. Extended XPS analysis and density functional theory (DFT) calculations revealed that surface carboxylic acid functional groups play a significant role in achieving the high activity of N-GA for 2e(-) ORR.