Simultaneously modulating the morphology and electronic structure of carbon-fiber: a strategy for constructing an efficient electrocatalyst for the in situ production of H2O2 over a wide pH

Abstract

The in situ production of H₂O₂via a two-electron oxygen reduction reaction (2e⁻ ORR) presents a sustainable alternative to the energy-intensive anthraquinone process. However, the development of efficient and stable electrocatalysts over a wide pH range remains a critical challenge. Herein, fluorine-doped porous carbon fiber (F–CF) was synthesized by simply annealing electrospun polytetrafluoroethylene (PTFE) and polyvinylpyrrolidone (PVP). The obtained F–CF has a hierarchical macro/meso/micro-pore structure due to the decomposition of PTFE, and it exhibits excellent 2e⁻ ORR catalytic activity and durability for H₂O₂ production over a wide pH range (3–14). In alkaline media, a remarkable H₂O₂ yield of 7.30 mol h⁻¹ g_cat.⁻¹ (0.3 V vs. RHE) with a faradaic efficiency (FE) of over 90% can be obtained. Notably, F–CF maintains outstanding performance and stability under neutral and even acidic conditions. Density functional theory (DFT) calculations reveal that F-doping regulates the electronic structure of CF, which can enhance its ability for O₂ adsorption and thus improve its catalytic performance for H₂O₂ production. The practicability of F–CF was further confirmed by the in situ production of H₂O₂ at different pHs: bleaching (alkaline), disinfection (neutral), and dye degradation (acidic). This work opens up a new way to design efficient carbon-based 2e⁻ ORR electrocatalysts by morphological and electronic structure engineering, broadening the prospects for decentralized H₂O₂ production in many fields.