Accelerated generation and activation of H2O2 by the synergetic effect of pyridine-N protonation and Co0 species toward efficient electro-Fenton

Abstract

Designing highly effective cathodic catalysts that can efficiently generate H₂O₂ in situ and promptly convert it to hydroxyl radicals (·OH) poses a significant challenge within the heterogeneous electro-Fenton (EF) systems. Herein, we fabricate a bifunctional core–shell catalyst featuring Co⁰ species encapsulated within N, P-codoped carbon shells through a hydrothermal-pyrolysis strategy, utilizing bamboo shoots as biomass-derived precursors. Density functional theory (DFT) calculations elucidate that the protonation of pyridinic nitrogen modifies the adsorption energy of the OOH* intermediate, positioning it optimally at the peak (3.81 eV) on the two-electron oxygen reduction reaction (2e⁻ ORR) volcano plot, thereby significantly boosting H₂O₂ production. Moreover, the Co⁰ species embedded within the catalyst function as electron donors, catalyzing the activation of H₂O₂ to produce ·OH by efficiently facilitating the transfer of electrons to Fe³⁺. Consequently, the synthesized catalyst exhibits a minimum electron transfer number of 2.06 and a maximum H₂O₂ selectivity of 97.4%. Moreover, the degradation for the methylene blue solution exceeds 95% within 15 min, with only an 11.3% reduction in degradation efficiency after 180 min of continuous operation (9 cycles). This bifunctional catalyst design provides valuable insights that can accelerate the development of EF-based degradation systems.