【作者】 李敏；

【导师】 梁鑫； 马晓玲；

【作者基本信息】 北京化工大学 ， 化学工程（专业学位）， 2019， 硕士

【摘要】 氢能由于高热值和无污染的特性成为解决能源和环境问题的重要能源,在众多的产氢反应中,电催化析氢反应由于原料易得和清洁的特点成为最优良的产氢途径,其催化剂主要为价格昂贵、储量极低的铂基催化剂,开发一种具有高催化活性且价格低廉的催化剂成为亟待解决的问题。本课题的研究重点在于制备具有高电催化析氢性能的复合结构过渡金属磷化物。选择金属有机骨架材料、羟基氧化物和合金材料不同类型前驱体,制备不同结构的复合结构双金属磷化物。通过改变磷化物的组成和结构,探究了组成和结构对于过渡金属磷化物电催化析氢反应催化性能的影响,体现了组成和结构双调控的实验思路。实验中,首先用溶剂热法合成金属有机骨架材料(FeCo-MIL88),经过高温碳化和低温磷化过程,制备了 FeCo@FeCoP@C多层中空纳米球材料,该材料在酸性条件下具有优越的电催化析氢反应性能,电流密度10 mA/cm2下过电势仅为66 mV,优于多数文献报道,且该材料具有良好的稳定性。将其与制备的Fe@FeP@C和Co@CoP@C材料进行活性对比,证明协同作用导致的组成效应对电催化析氢反应的影响;与直接磷化产物FeCoP-direct对比,证明了该结构的强导电性和对催化组分FeCoP的保护作用对电催化析氢反应性能的促进作用,并称之为结构效应。利用水热法合成了羟基氧化物Fe/CoOOH前驱体,经过磷化作用得到中空纳米棒FeCoP/Fe3O4,通过与FeP/Fe3O4的电催化析氢反应性能对比,证明了协同效应对电催化析氢反应的促进作用;与酸洗后的FeCoP进行性能对比,证明含Fe3O4复合结构由于高导电性使得其电催化析氢反应性能提升。最后,以硼氢化钠强还原剂还原得到双金属FeCo合金,经过磷化作用,得到部分磷化产物FeCo@FeCoP,该材料的电催化析氢反应性能优于所制备的FeP、CoP、(Fe@Co)P和(Co@Fe)P,分析该原因主要在于FeP和CoP之间的协同效应使得FeCo@FeCoP具有较FeP和CoP更好的电催化析氢反应性能;通过与(Co@Fe)P的性能对比,证明内部合金结构的存在使得FeCo@FeCoP具有良好的导电性,且表面FeCoP难以氧化,进而增强了电催化析氢反应性能;与(Fe@Co)P活性差异原因主要在于Fe和Co的均匀混合程度将在一定程度上影响制备的材料的协同效应,进而对电催化析氢反应性能具有一定的影响。基于三种不同前驱体制备的复合结构过渡金属磷化物均在酸性条件下体现出较非复合结构过渡金属磷化物更好的电催化析氢反应性能,证明结构效应在电催化析氢反应中的重要作用;同时与单一金属的过渡金属磷化物对比,证明组成效应亦是影响电催化析氢反应性能的重要因素。更多还原

【Abstract】 Hydrogen,a clean energy with high energy density,shows great potentiality to solve the energy and environmental problems.Due to the abundant of raw materials and cleanliness,electrocatalytic hydrogen evolution reaction can be an excellent hydrogen production route.Pt-based catalysts,which is expensive and limited reserves,are the main catalysts for hydrogen evolution reaction.So developing the catalysts with high activity and low cost has become an urgent problem to be solved.In this work,We focus on preparing a composite structure transition bimetal phosphide with high electrocatalytic hydrogen evolution performance.Different types of precursors of metal organic framework materials,oxyhydroxides and alloy are selected to prepare composite structure bimetallic phosphides with different structures.The key point is the effects of composition and structure for the hydrogen evolution reaction performance of transition metal phosphide,reflecting the experimental idea of composition and structure double regulation.First,we prepared the metal-organic framework(FeCo-MIL88)by solvothermal merthod.Through the carbonization and phosphating process,multi-layered FeCo@FeCoP@C hollowspheres were synthesized,which showed the outstanding electrocatalytic activity and great stability for HER.It only need 66 mV overpotential to reach 10 mA/cm2 current density,superior to the HER electrocatalysts by most reported.Comparing with Fe@FeP@C and Co@CoP@C,the high hydrogen evolution reation activity can be attributed to the compositon effect;Comparing with FeCoP-direct(directly phosphating production),the composite of FeCo and carbon of FeCo@FeCoP@C enhance the electron transportation ability and protect the FeCoP from oxidation,which resulting the greater hydrogen evolution reaction activity(structure effect).Second,we prepared the Fe/CoOOH as the precursor by hydrothermal,then prepared the FeCoP/Fe3O4 hollow nanorobds.The composition effect on hydrogen evolution reaction can be proved by compareing with the FeP/Fe3O4;To prove the structure effect,we prepared FeCoP by acid treatment,the Fe3O4 of FeCoP/Fe3O4 can enhance the electron transportation ability,leading FeCoP/Fe3O4 owning the higher hydrogen evolution reaction activity.Finally,we prepared the FeCo alloy reducted by sodium borohydride and got the production FeCo@FeCoP by partially phosphating.The hydrogen evolution reaction activity of FeCo@FeCoP is much higher than FeP,CoP,(Fe@Co)P and(Co@Fe)P.Comparing with FeP and CoP,the composition effect can be proved.The difference of the activity between FeCo@FeCoP and(Co@Fe)P can be attributed to the FeCo alloy of FeCo@FeCoP,which leads the high electron transportation ability and protects the FeCoP from oxidation.As for the(Fe@Co)P,the lower overpotioanl of FeCo@FeCoP at the same current density can be attributed to the uniform mixing of iron and cobalt,leading the uniform mixing of FeP and CoP,it’s important for the composition effect.Based the different precursors,the transition bimetal phosphides with composite structures are successfully prepared,and show the greater hydrogen evolution reaction than non-composite transition metal phosphides.It can be attributed to the structure effect.At the same time,compared with the transition metal phosphide of single metal,it can be proved that the composition effect is also an important factor affecting the performance of electrocatalytic hydrogen evolution reaction.更多还原