Carbon Nanosheets Containing Discrete Co-Nx-By-C Active Sites for Efficient Oxygen Electrocatalysis and Rechargeable Zn-Air Batteries
Carbon Nanosheets Containing Discrete Co-Nx-By-C Active Sites for Efficient Oxygen Electrocatalysis and Rechargeable Zn-Air Batteries
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含有离散 Co-Nx-By-C 活性位点的碳纳米片，用于高效氧电催化和可充电锌空气电池
DOI：
10.1021/acsnano.7b08721
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发表时间：
2018-02-01
期刊：
影响因子：
17.1
通讯作者：
Mu, Shichun
中科院分区：
文献类型：
--
作者：
Guo, Yingying;Yuan, Pengfei;Mu, Shichun
原子级金属-N-C催化剂的结构和组成工程在提高其用于氧还原反应（ORR）和析氧反应（OER）的性能方面是重要的但具有挑战性的。本文采用软模板自组装热解法制备了多级多孔碳片（Co-N，B-CSs）中硼（B）掺杂的Co-N-C活性位。值得注意的是，引入的B元素提供了缺电子位点，其可以激活Co-N-C位点周围的电子转移，加强与含氧物质的相互作用，从而加速4 e（-）处理的ORR和OER中的反应动力学。结果，该催化剂显示出类似Pt的ORR性能，半波电位（E-1/2）为0.83 V（vs）RHE，极限电流密度为约5.66 mA cm（-2），并且比Pt/C催化剂具有更高的耐久性（在5000次循环后几乎没有衰减）。此外，包含该Co-N，B-CSs催化剂的可再充电Zn-空气电池装置显示出上级性能，其开路电势类似于1.4 V，峰值功率密度类似于100.4 mW cm（-2），以及优异的耐久性（14小时操作128次循环）。DFT计算进一步证明了Co-N-x活性位点与B原子的偶联倾向于以侧面模式吸附O2分子并加速ORR动力学。
Structural and compositional engineering of atomic scaled metal-N-C catalysts is important yet challenging in boosting their performance for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Here, boron (B)-doped Co-N-C active sites confined in hierarchical porous carbon sheets (denoted as Co-N,B-CSs) were obtained by a soft template self-assembly pyrolysis method. Significantly, the introduced B element gives an electron deficient site that can activate the electron transfer around the Co-N-C sites, strengthen the interaction with oxygenated species, and thus accelerate reaction kinetics in the 4e(-) processed ORR and OER. As a result, the catalyst showed Pt-like ORR performance with a half-wave potential (E-1/2) of 0.83 V versus (vs) RHE, a limiting current density of about 5.66 mA cm(-2), and higher durability (almost no decay after 5000 cycles) than Pt/C catalysts. Moreover, a rechargeable Zn-air battery device comprising this Co-N,B-CSs catalyst shows superior performance with an open-circuit potential of similar to 1.4 V, a peak power density of similar to 100.4 mW cm(-2), as well as excellent durability (128 cycles for 14 h of operation). DFT calculations further demonstrated that the coupling of Co-N-x active sites with B atoms prefers to adsorb an 02 molecule in side-on mode and accelerates ORR kinetics.