开发低成本、高性能的析氢反应(HER)电催化剂是实现电解水制氢规模化的关键.本文以MXene(Ti3C2Tx)为导电基底,以2-甲基咪唑和钼酸铵为原材料,通过室温溶液沉积制备出Mo-MOF/MXene前驱体,然后在Ar气氛下退火制得Mo2C/MXene@NC复合催化材料.SEM和TEM表征结果表明MXene具有层状结构,大的比表面积为Mo2C纳米点在MXene表面均匀分散提供了基础,且进一步增加了活性位点,同时Mo2C与导电性优良的MXene强耦合,调节了复合材料的电子结构,促进电子的转移,从而提升了催化性能.另外,Mo-MOF在MXene表面的原位沉积及转化的NC材料也确保了 MXene结构在高温下的稳定性.实验结果显示,在600℃温度下制备的Mo2C/MX-ene@NC催化剂,在1 mol·L-1 KOH溶液中显现出了优异的HER性能,在电流密度为10 mA cm-2时的过电位为210 mV,Tafel斜率为180 mV dec-1,并能在16 h内保持催化剂性能的稳定性.本实验不仅提供了一种高活性钼基HER催化剂的制备策略,而且为高温合成MXene基纳米复合材料开辟了途径.
Preparation of Mo2C/MXene@NC composites and its performance for hydrogen production by electrolytic water
The development of low-cost,high-performance hydrogen evolution reaction(HER)electrocatalysts is the key to achieve large-scale hydrogen production by water electrolysis.In this paper,Mo2C/MXene@NC composites were prepared by solution deposi-tion at room temperature with MXene(Ti3C2Tx)as the conductive substrate,2-methylimidazole and ammonium molybdate as the raw materials,and then the precipitates were annealed in Ar atmosphere to obtain Mo2C/MXene@NC.The characterization results show that Mo2C nanodots are uniformly dispersed on the MXene surface,where MXene provides a larger specific surface area,Mo2C increa-ses the active sites,and the strong coupling between Mo2C and the conductive MXene regulates the electronic structure to accelerate the electron transfer.In addition,Mo-MOF in-situ formed on MXene maintains the structural stability of MXene at high carbonization tem-perature.The experimental results indicate that Mo2C/MXene@NC catalyst prepared at 600℃ shows excellent HER performance in 1 mol·L-1 KOH solution and long term stability over 16 h,with an overpotential of 210 mV at 10 mA cm-2 and the smallest Tafel slope of 180 mV dec-1.This experiment not only provides a high activity HER Mo-based catalyst preparation strategy,but also opens up a way for high temperature synthesis of MXene-based nanocomposites.
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