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

The <i>in situ</i> production of H₂O₂<i>via</i> 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 <i>vs.</i> 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 <i>in situ</i> 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.