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<p>Decoding the nature of catalytically active sites is an essential prerequisite for the rational design of catalysts for electrochemical H<sub>2</sub>O<sub>2</sub> synthesis, but faces significant challenges, particularly for controversial cobalt single-atom catalysts (Co SACs). Herein, we report trace Co single-atom sites embedded within pyridinic N-rich carbon nanospheres (Co<sub>1</sub>-N<sub>NH3</sub>-C), synthesized via a self-assembly coupled surface-coating strategy. The Co<sub>1</sub>-N<sub>NH3</sub>-C catalyst demonstrates remarkable H<sub>2</sub>O<sub>2</sub> selectivity (99%) and activity at current density of −3.5 mA cm<sup>−2</sup> in 0.1 M H<sub>2</sub>SO<sub>4</sub>. Through a combined approach of molecular probe experiments, surface modification, and density functional theory (DFT) calculations, we disclose that pyridinic N, rather than Co single atoms, serves as the direct active site for 2e<sup>−</sup> oxygen reduction reaction (ORR). The trace Co (0.05 wt%) indirectly facilitated pyridinic N formation during pyrolysis but exhibits negligible direct catalytic involvement. DFT reveals pyridinic N sites optimize OOH intermediate adsorption (Δ<i>G</i>*OOH = 4.0 eV) and minimize reaction overpotential of 0.20 V, enabling scalable H<sub>2</sub>O<sub>2</sub> production (907.5 mmol g<sub>cat</sub><sup>−1</sup> h<sup>−1</sup>). This work redefines the role of trace metal in SACs, providing a paradigm for designing metal-induced carbon catalysts for sustainable electrosynthesis for H<sub>2</sub>O<sub>2</sub>.</p>

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Decoding the true active site in cobalt single-atom catalysts: pyridinic nitrogen-dominated electrosynthesis of hydrogen peroxide in acidic media

  • 期刊论文

  • 发表日期：

    2026年3月13日

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  • Huijuan Yang,
  • Yifan Li,
  • Xiaoyu Yi,
  • Lina Chen,
  • Kang Qi,
  • Guiqiang Cao,
  • Wei Xiao,
  • Chong Xie,
  • Xifei Li

摘要

Decoding the nature of catalytically active sites is an essential prerequisite for the rational design of catalysts for electrochemical H2O2 synthesis, but faces significant challenges, particularly for controversial cobalt single-atom catalysts (Co SACs). Herein, we report trace Co single-atom sites embedded within pyridinic N-rich carbon nanospheres (Co1-NNH3-C), synthesized via a self-assembly coupled surface-coating strategy. The Co1-NNH3-C catalyst demonstrates remarkable H2O2 selectivity (99%) and activity at current density of −3.5 mA cm−2 in 0.1 M H2SO4. Through a combined approach of molecular probe experiments, surface modification, and density functional theory (DFT) calculations, we disclose that pyridinic N, rather than Co single atoms, serves as the direct active site for 2e− oxygen reduction reaction (ORR). The trace Co (0.05 wt%) indirectly facilitated pyridinic N formation during pyrolysis but exhibits negligible direct catalytic involvement. DFT reveals pyridinic N sites optimize OOH intermediate adsorption (ΔG*OOH = 4.0 eV) and minimize reaction overpotential of 0.20 V, enabling scalable H2O2 production (907.5 mmol gcat−1 h−1). This work redefines the role of trace metal in SACs, providing a paradigm for designing metal-induced carbon catalysts for sustainable electrosynthesis for H2O2.