Jiang Hao, Liu Yong, Li Wenzhang, Li Jie
School of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan, 410083, China.
Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Changsha, Hunan, 410083, China.
Small. 2018 Mar;14(13):e1703739. doi: 10.1002/smll.201703739. Epub 2018 Feb 12.
Proper design and simple preparation of nonnoble bifunctional electrocatalysts with high cost performance and strong durability for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) is highly demanded but still full of enormous challenges. In this work, a spontaneous gas-foaming strategy is presented to synthesize cobalt nanoparticles confined in 3D nitrogen-doped porous carbon foams (CoNCF) by simply carbonizing the mixture of citric acid, NH Cl, and Co(NO ) ·6H O. Thanks to its particular 3D porous foam architecture, ultrahigh specific surface area (1641 m g ), and homogeneous distribution of active sites (C-N, Co-N , and Co-O moieties), the optimized CoNCF-1000-80 (carbonized at 1000 °C, containing 80 mg Co(NO ) ·6H O in precursors) catalyst exhibits a remarkable bifunctional activity and long-term durability toward both ORR and OER. Its bifunctional activity parameter (ΔE) is as low as 0.84 V, which is much smaller than that of noble metal catalyst and comparable to state-of-the-art bifunctional catalysts. When worked as an air electrode catalyst in rechargeable Zn-air batteries, a high energy density (797 Wh kg ), a low charge/discharge voltage gap (0.75 V), and a long-term cycle stability (over 166 h) are achieved at 10 mA cm .
对于氧还原反应（ORR）和析氧反应（OER），迫切需要设计合理且制备简单的具有高性价比和强耐久性的非贵金属双功能电催化剂，但这仍然充满巨大挑战。在这项工作中，提出了一种自发气体发泡策略，通过简单地碳化柠檬酸、NH₄Cl和Co(NO₃)₂·6H₂O的混合物来合成限制在三维氮掺杂多孔碳泡沫（CoNCF）中的钴纳米颗粒。由于其特殊的三维多孔泡沫结构、超高比表面积（1641 m²/g）以及活性位点（C-N、Co-Nₓ和Co-O部分）的均匀分布，优化后的CoNCF-1000-80（在1000°C碳化，前驱体中含有80 mg Co(NO₃)₂·6H₂O）催化剂对ORR和OER均表现出显著的双功能活性和长期耐久性。其双功能活性参数（ΔE）低至0.84 V，远小于贵金属催化剂，与最先进的双功能催化剂相当。当用作可充电锌空气电池的空气电极催化剂时，在10 mA/cm²的电流密度下，可实现高能量密度（797 Wh/kg）、低充放电电压间隙（0.75 V）和长期循环稳定性（超过166小时）。
