Li Hao, Chen Xiao, Chen Junying, Shen Kui, Li Yingwei
Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
Nanoscale. 2021 Jun 17;13(23):10500-10508. doi: 10.1039/d1nr01603b.
Rationally designing low-cost yet highly efficient electrocatalysts for the oxygen reduction reaction (ORR) in both alkaline and acidic media remains highly challenging. Herein, we report the facile synthesis of Fe,N-doped carbon nanorods (denoted as Fe-N/C-NR) with abundant hierarchical pores and highly active sites by the pyrolysis of a one-dimensional (1D) Fe-doped zeolitic imidazolate framework (Fe-ZIF-8) as a self-sacrificing template. The unique 1D nanoarchitecture of the resultant Fe-N/C-NR can provide fast electron and electrolyte transport towards exposed active sites, and their hierarchically porous structures with large surface areas can efficiently facilitate mass diffusion and increase the density of exposed active sites. Furthermore, it is demonstrated that the coexistence of highly dispersed Fe-Nx sites and Fe3C/Fe nanoparticles (NPs) in these electrocatalysts can provide a large number of desired catalytic centers with highly intrinsic activity and structural stability. As a result, the optimized 5Fe-N/C-NR exhibits excellent catalytic activity for the ORR, with a high half-wave potential (E1/2) of 0.90 V vs. RHE in alkaline medium, superior to that of commercial Pt/C (0.86 V vs. RHE), and also a high E1/2 of 0.81 V vs. RHE in acidic medium, comparable to that of commercial Pt/C (0.81 V vs. RHE). Moreover, its robust ORR durability can far surpass that of commercial Pt/C in both acidic and alkaline media, further highlighting the merit of this MOF-templated strategy. Our findings might shed light on the rational design of cost-effective and highly efficient ORR electrocatalysts for practical applications.
合理设计在碱性和酸性介质中用于氧还原反应（ORR）的低成本且高效的电催化剂仍然极具挑战性。在此，我们报道了通过热解一维（1D）铁掺杂沸石咪唑酯骨架（Fe-ZIF-8）作为自牺牲模板，简便合成具有丰富分级孔隙和高活性位点的铁、氮掺杂碳纳米棒（记为Fe-N/C-NR）。所得Fe-N/C-NR独特的一维纳米结构能够为暴露的活性位点提供快速的电子和电解质传输，并且它们具有大表面积的分级多孔结构能够有效地促进质量扩散并增加暴露活性位点的密度。此外，已证明这些电催化剂中高度分散的Fe-Nx位点与Fe3C/Fe纳米颗粒（NPs）的共存能够提供大量具有高本征活性和结构稳定性的理想催化中心。结果，优化后的5Fe-N/C-NR对ORR表现出优异的催化活性，在碱性介质中相对于可逆氢电极（RHE）的半波电位（E1/2）高达0.90 V，优于商业Pt/C（0.86 V vs. RHE），在酸性介质中相对于RHE的E1/2也高达0.81 V，与商业Pt/C相当（0.81 V vs. RHE）。此外，其强大的ORR耐久性在酸性和碱性介质中都能远远超过商业Pt/C，进一步突出了这种以金属有机框架为模板的策略的优点。我们的发现可能为实际应用中具有成本效益和高效的ORR电催化剂的合理设计提供启示。
