镍基MOF衍生Ni@PC用于氧还原催化性能研究

Preparation of nickel-based MOF-derived Ni@PC and its catalytic performance for oxygen reduction reaction

开发高效、低成本的非贵金属氧还原催化剂是提高燃料电池效率的关键。以六水合硝酸镍和二甲基咪唑作为金属源和氮源,制备Ni-MOF前驱体,并采用低温热解法合成了纳米棒状镍掺杂多孔碳(Ni@PC)复合材料。通过扫描电子显微镜、X射线衍射仪、拉曼光谱和物理吸附仪等多种表征手段,对催化剂进行形貌和结构表征。利用旋转圆盘电极技术测试了其氧还原催化性能。结果表明:Ni@PC呈现三维交错的纳米棒状,其比表面积为178.7m^(2)/g,具有介孔结构。在0.1mol/L KOH电解液中,Ni@PC的氧还原起始电位为0.89V(vs RHE),其极限电流密度可达4.91mA/cm^(2),在动力学电位区,Ni@PC的Tafel斜率为64mV/dec,氧气分子在Ni@PC催化剂上以四电子机理反应还原成水,该催化剂具有优异的耐久性和抗甲醇稳定性。因此,Ni@PC有望替代商业Pt/C催化剂,在能源领域具有广阔的应用前景。

The development of highly efficient and low-cost non-precious metal oxygen reduction catalysts is the key to improve the efficiency of fuel cells.Ni-MOF precursors were prepared by nickel nitrate hexahydrate and dimethylimidazole as metal and nitrogen sources,respectively,and then the nanorod-shaped nickel-doped porous carbon(Ni@PC)composite was synthesized by low-temperature pyrolysis.The morphology and structure of the catalysts was characterized by scanning electron microscopy,X-ray diffraction apparatus,Raman spectroscopy and physical sorption apparatus.Its catalytic performance for the oxygen reduction reaction was tested using a rotating disc electrode technique.The results showed that Ni@PC presented a three-dimensional staggered nanorod shape with a specific surface area of 178.7m^(2)/g and a mesoporous structure.In 0.1mol/L KOH electrolyte,the onset potential for oxygen reduction reaction of Ni@PC was 0.89V(vs RHE),and its limiting current density was up to 4.91mA/cm^(2).In the kinetic potential region,the Tafel slope of Ni@PC was 64mV/dec,and the oxygen molecule was reduced to water in a four-electron mechanism reaction on the Ni@PC catalyst.The catalyst had excellent durability and stability against methanol.Therefore,Ni@PC was expected to replace commercial Pt/C catalysts and had broad application prospects in the energy field.