Pyrimidine-assisted synthesis of S, N-codoped few-layered graphene for highly efficient hydrogen peroxide production in acid

Abstract

H 2 O 2 production by electroreduction of oxygen is an attractive alternative to replace the current complex anthraquinone method. However, it is still challenging to realize efficient electrochemical H 2 O 2 production in acid by using cost-effective catalysts. Herein, we report a pyrimidine-assisted chemical-vapor-deposition method to synthesize sulfur-and-nitrogen-codoped few-layered graphene (SNGL) with exceptional activity and selectivity for two-electron oxygen reduction reaction (2e − ORR) in acidic electrolyte (pH = 1). The H 2 O 2 selectivity reaches 90%–100% over a potential range of 0.20–0.55 V, and the maximum H 2 O 2 production rate (4.8 mol g −1 ·h −1 ) exceeds all of the reported H 2 O 2 production performance for carbon-material-based catalysts. Experiments and density functional theory (DFT) simulations reveal that the synergy effect of the combined oxidized sulfur and pyridinic N functional motif can lower the Fermi level of valence electronic states of active edge carbon sites and thus leads to suitable binding strength of ∗OOH intermediate for high selectivity and performance 2e − ORR for H 2 O 2 formation. • Pyrimidine mediates to form S, N-codoped few-layered graphene (SNGL) catalysts • The SNGL catalyst performed a recorded H 2 O 2 production rate • XAS evidences the valence electronic modification for oxygen-adsorption optimization • DFT simulation identified the potential catalytic active sites As one of the 100 most important chemicals in the world, hydrogen peroxide (H 2 O 2 ) is mainly produced by the energy- and waste-intensive anthraquinone oxidation (AO) method. Replacing the AO method with a more environmentally benign electrochemical two-electron oxygen reduction reaction (2e − ORR) depends on low-cost and efficient catalysts. However, metal-free, carbon-based catalyst as a promising candidate behaves encouragingly only under neutral or alkaline conditions, where H 2 O 2 is unstable for collection or unfavorable for linking applications, i.e., the e -Fenton reaction. Herein, we developed a pyrimidine-mediated synthetic method to synthesize S, N-codoped few-layered graphene (SNGL) with surface electronic property optimization, which significantly boosts 2e − ORR in acid. Our work not only created an efficient carbon-based catalyst for H 2 O 2 production in acid but also provided a useful electronic property optimization route for future tuning of carbon-based materials catalysts. A pyrimidine-assisted synthetic method is developed to synthesize sulfur-and-nitrogen-codoped few-layered graphene (SNGL) with optimized valence electronic density for efficient H 2 O 2 electrosynthesis in acid.