Li Zeyu, Gao Qiuming, Qian Weiwei, Tian Weiqian, Zhang Hang, Zhang Qiang, Liu Zhengping
Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, Beijing Key Laboratory of Bio-inspired Energy Materials and Devices, School of Chemistry, Beihang University, Beijing, 100191, P. R. China.
Institute of Polymer Chemistry and Physics of College of Chemistry, BNU Lab of Environmentally Friendly and Functional Polymer Materials, Beijing Normal University, Beijing, 100875, P. R. China.
Sci Rep. 2018 Feb 12;8(1):2863. doi: 10.1038/s41598-018-21213-3.
Hierarchical nanoporous N-doped carbon ZNC-1000 was prepared by facile pyrolysis of well-designed nanosized ZIF-8 precursor with optimized reaction temperature and time. It possesses large surface areas leading to sufficient exposed electrochemical active sites. Meanwhile, its moderate graphitization degree and suitable nanosized hierarchical porosity distributions would lead to the sufficient interaction between O and the electrocatalyst surface which would benefit the transports of electrons and the electrolyte ions for ORR. As an electrocatalyst for oxygen reduction reaction, the ZNC-1000 presents a better catalytic property than the commercial Pt/C with 6/1 mV positive shifts for onset/half-wave potentials and 1.567 mA cm larger for limiting current density respectively. The stability of ZNC-1000 is also much better than that of Pt/C with negative shifts of 0/-2 mV (vs 5/31 mV) for onset/half-wave potentials and 6.0% vs 29.2% loss of limiting current density after 5000 cycles of accelerated durability test, as well as the relative current of 87.5% vs 40.2% retention after 30,000 s continuous chronoamperometric operation.
通过对精心设计的纳米级ZIF-8前驱体进行简单热解，并优化反应温度和时间，制备出了具有分级纳米孔结构的N掺杂碳ZNC-1000。它具有较大的表面积，从而导致足够数量的电化学活性位点得以暴露。同时，其适度的石墨化程度和合适的纳米级分级孔隙率分布会使氧与电催化剂表面之间产生充分的相互作用，这将有利于电子和电解质离子在氧还原反应（ORR）中的传输。作为一种氧还原反应的电催化剂，ZNC-1000表现出比商业Pt/C更好的催化性能，其起始/半波电位分别正移6/1 mV，极限电流密度比Pt/C大1.567 mA cm²。在经过5000次加速耐久性测试后，ZNC-1000的稳定性也远优于Pt/C，其起始/半波电位负移0/-2 mV（对比Pt/C的5/31 mV），极限电流密度损失6.0%，对比Pt/C的29.2%；在经过30000 s连续计时电流法操作后，相对电流保留率为87.5%，对比Pt/C的40.2%。
