The oxygen reduction reaction (ORR) is a crucial process in zinc–air batteries (ZABs), but its sluggish kinetics impedes the widespread application of ZABs. Herein, balsa wood-derived carbon embedded with nitrogen and sulfur atoms was proposed as a metal-free carbon electrocatalyst to enhance the ORR kinetics process for ZABs. Wood carbonization/activation and N, S co-doping were simultaneously achieved in a one-step high-temperature pyrolysis, resulting in the formation of N, S-doped carbonized wood (NSCW-900). The resultant NSCW-900 showed well-aligned microchannels/hierarchical pores, large specific surface area and good wettability, increasing activation sites and improving reaction kinetics. The introduction of N and S atoms modified the electronic structure of the neighbouring carbon atoms, enabling a redistribution of charge for enhancing the intrinsic catalytic activity. Numerous graphitic nitrogen, pyridinic nitrogen and thiophene sulphur sites were exposed adequately, providing good electronic conductivity and facilitating the mass transfer of reactants. The NSCW-900 showed a high half-wave potential of 0.832 V vs. the reversible hydrogen electrode (RHE) and a high onset potential of 0.93 V (vs. RHE), along with excellent methanol tolerance and long-term stability. The assembled rechargeable liquid ZABs exhibited a maximum output power density of 149 mW cm⁻², with a low voltage gap of 0.87 V over a prolonged 125-hour cycling. This work provides a novel carbon-based ORR electrocatalyst via utilizing balsa wood nanostructures and regulating the electronic structure of carbon atoms, facilitating the development of next-generation energy storage devices.

中文翻译：

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木材碳原子的电子结构调控提高 Zn-air 电池性能


氧还原反应 （ORR） 是锌空气电池 （ZAB） 中的关键过程，但其缓慢的动力学阻碍了 ZAB 的广泛应用。在此，提出了嵌入氮和硫原子的轻木衍生碳作为无金属碳电催化剂，以增强 ZABs 的 ORR 动力学过程。在一步高温热解中同时实现木材碳化/活化和 N、S 共掺杂，从而形成 N、S 掺杂碳化木材 （NSCW-900）。所得 NSCW-900 显示出对齐良好的微通道/多级孔、大比表面积和良好的润湿性，增加了活化位点并改善了反应动力学。N 和 S 原子的引入改变了相邻碳原子的电子结构，使电荷能够重新分配以增强本征催化活性。许多石墨氮、吡啶氮和噻吩硫位点被充分暴露，提供了良好的电子导电性并促进了反应物的质量传递。NSCW-900 显示出 0.832 V 的高半波电位（相对于可逆氢电极 （RHE）和 0.93 V 的高起始电位（相对于 RHE），以及优异的甲醇耐受性和长期稳定性。组装的可充电液体 ZAB 的最大输出功率密度为 149 mW ^cm-2，在 125 小时的长时间循环中具有 0.87 V 的低电压间隙。这项工作通过利用轻木纳米结构和调节碳原子的电子结构，提供了一种新型碳基 ORR 电催化剂，促进了下一代储能器件的开发。