Li Jia, Chen Siguo, Yang Na, Deng Mingming, Ibraheem Shumaila, Deng Jianghai, Li Jing, Li Li, Wei Zidong
Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization, School of Chemistry and Engineering, Chongqing University, Shazhengjie 174, Chongqing, 400044, China.
Angew Chem Int Ed Engl. 2019 May 20;58(21):7035-7039. doi: 10.1002/anie.201902109. Epub 2019 Apr 12.
Atomically dispersed Zn-N-C nanomaterials are promising platinum-free catalysts for the oxygen reduction reaction (ORR). However, the fabrication of Zn-N-C catalysts with a high Zn loading remains a formidable challenge owing to the high volatility of the Zn precursor during high-temperature annealing. Herein, we report that an atomically dispersed Zn-N-C catalyst with an ultrahigh Zn loading of 9.33 wt % could be successfully prepared by simply adopting a very low annealing rate of 1° min . The Zn-N-C catalyst exhibited comparable ORR activity to that of Fe-N-C catalysts, and significantly better ORR stability than Fe-N-C catalysts in both acidic and alkaline media. Further experiments and DFT calculations demonstrated that the Zn-N-C catalyst was less susceptible to protonation than the corresponding Fe-N-C catalyst in an acidic medium. DFT calculations revealed that the Zn-N structure is more electrochemically stable than the Fe-N structure during the ORR process.
原子级分散的Zn-N-C纳米材料是用于氧还原反应（ORR）的有前景的无铂催化剂。然而，由于高温退火过程中锌前驱体的高挥发性，制备具有高锌负载量的Zn-N-C催化剂仍然是一项艰巨的挑战。在此，我们报道通过简单地采用1°/分钟的极低退火速率，可以成功制备出锌负载量高达9.33 wt%的原子级分散的Zn-N-C催化剂。该Zn-N-C催化剂在酸性和碱性介质中均表现出与Fe-N-C催化剂相当的ORR活性，并且ORR稳定性明显优于Fe-N-C催化剂。进一步的实验和密度泛函理论（DFT）计算表明，在酸性介质中，Zn-N-C催化剂比相应的Fe-N-C催化剂更不易质子化。DFT计算表明，在ORR过程中，Zn-N结构比Fe-N结构在电化学上更稳定。
