Qiao Mengfei, Wang Ying, Wang Quan, Hu Guangzhi, Mamat Xamxikamar, Zhang Shusheng, Wang Shuangyin
Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, School of Chemical Science and Technology, Yunnan University, Kunming, 650504, China.
Key Laboratory of Chemistry of Plant Resources in Arid Regions, State Key Laboratory Basis of Xinjiang Indigenous Medicinal Plants Resource Utilization, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Science, Urumqi, 830011, China.
Angew Chem Int Ed Engl. 2020 Feb 10;59(7):2688-2694. doi: 10.1002/anie.201914123. Epub 2020 Jan 28.
The low catalytic activity and poor mass transport capacity of platinum group metal free (PGM-free) catalysts seriously restrict the application of proton-exchange membrane fuel cells (PEMFCs). Catalysts derived from Fe-doped ZIF-8 could in theory be as active as Pt/C thanks to the high intrinsic activity of FeN ; however, the micropores fail to meet rapid mass transfer. Herein, an ordered hierarchical porous structure is introduced into Fe-doped ZIF-8 single crystals, which were subsequently carbonized to obtain an FeN -doped hierarchical ordered porous carbon (FeN /HOPC) skeleton. The optimal catalyst FeN /HOPC-c-1000 shows excellent performance with a half-wave potential of 0.80 V in 0.5 m H SO solution, only 20 mV lower than that of commercial Pt/C (0.82 V). In a real PEMFC, FeN /HOPC-c-1000 exhibits significantly enhanced current density and power density relative to FeN /C, which does not have an optimized pore structure, implying an efficient utilization of the active sites and enhanced mass transfer to promote the oxygen reduction reaction (ORR).
无铂族金属（PGM-free）催化剂的低催化活性和较差的传质能力严重限制了质子交换膜燃料电池（PEMFC）的应用。理论上，由于FeN的高本征活性，源自铁掺杂ZIF-8的催化剂可能与Pt/C具有相同的活性；然而，微孔无法满足快速传质的需求。在此，将有序的分级多孔结构引入铁掺杂ZIF-8单晶中，随后将其碳化以获得FeN掺杂的分级有序多孔碳（FeN/HOPC）骨架。最优催化剂FeN/HOPC-c-1000在0.5 m H₂SO₄溶液中表现出优异的性能，半波电位为0.80 V，仅比商业Pt/C（0.82 V）低20 mV。在实际的PEMFC中，相对于没有优化孔结构的FeN/C，FeN/HOPC-c-1000表现出显著提高的电流密度和功率密度，这意味着活性位点得到有效利用，传质增强，从而促进氧还原反应（ORR）。
