具有丰富活性位点和高电子传导性的非晶MOF用于高效肼氧化  

Amorphization of MOFs with rich active sites and high electronic conductivity for hydrazine oxidation

作　　者：丁婕婷 王浩帆 沈葵 韦小明 陈立宇 李映伟 Jieting Ding;Hao-Fan Wang;Kui Shen;Xiaoming Wei;Liyu Chen;Yingwei Li(Guangdong Provincial Key Laboratory of Fuel Cell Technology,School of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou 510640,Guangdong,China;School of Physics and Optoelectronics,South China University of Technology,Guangzhou 510640,Guangdong,China)

机构地区：[1]华南理工大学化学与化工学院广东省燃料电池技术重点实验室,广东广州510640 [2]华南理工大学物理与光电学院,广东广州510640

出　　处：《Chinese Journal of Catalysis》2024年第5期351-359,共9页催化学报（英文）

基　　金：国家自然科学基金(21825802,22138003,22108083,22378136);制浆造纸工程国家重点实验室项目(2022C04,2022ZD05,2023PY06);广东省珠江人才计划项目(2021ZT09Z109,2021QN02C8);广东省自然科学基金(2023B1515040005,2023A1515010312,2024A1515011196);广州市科技计划项目(202201010118,2023A04J0674);清远市科技计划项目(2021YFJH01002);中央高校基本科研业务费项目(2022ZYGXZR017,2022ZYGXZR108,2022ZYGXZR048).

摘　　要：金属有机框架(MOF)虽然具有完美的结晶性质,但由于其配位不饱和位点数量不足和电子传导性较低,这些特性限制了它在电催化领域的应用.尽管通过去除部分有机配体可以暴露晶体MOF的一些金属位点,但常用的方法涉及高压、高温、强酸、强碱等苛刻的条件,很容易造成MOF的多孔结构完全坍塌.相较于晶态MOF,非晶态MOF具有短程有序而长程无序的结构特征.通过快速组装MOF,有望实现MOF的非晶化,从而创造大量不饱和位点,并优化金属位点的电子结构.因此,开发高效的非晶态MOF合成策略十分必要.本文报道了一种诱导非晶态MOF在碳布上快速组装的电合成方法,制得了具有丰富活性位点和高电子传导性的非晶态MOF(记为aMnFc'/CC).在电合成过程中,有机配体在碳布上迅速去质子化,并与金属离子快速组装,形成具有大量配位不饱和Mn位点的非晶态aMnFc'.X射线衍射和透射电镜选区电子衍射结果表明,aMnFc'为无定形结构.电子顺磁共振和X射线吸收近边结构光谱等表明,aMnFc'比cMnFc'含有更多的不饱和Mn金属中心.随后,利用三电极体系评估催化剂在肼氧化(HzOR)中的催化活性,在0.1 mol L^(−1) PBS+0.4 mol L^(−1) N_(2)H_(4)电解质中,aMnFc'/CC的起始电位为287 mV(1 mA cm^(−2)),在10 mA cm^(−2)下的工作电势为667 mV,其活性远优于晶态MOF 起始电位为540 mV(1 mA cm^(−2)),在10 mA cm^(−2)下的工作电势为(871 mV).aMnFc'/CC在0.1 mol L^(−1) PBS中的HzOR性能优于大多数已报道的Mn/Fe基催化剂和MOFs催化剂.四探针法测定cMnFc'和aMnFc'的电导率分别为1.5×10^(−4)和1.8×10^(−3) S cm^(−2),表明MOF的非晶化可以提高电导率,从而增强其电化学性能.密度泛函理论计算表明,MnFc'-V在费米能级附近的态密度比MnFc'的态密度更强,说明不饱和Mn中心的存在增强了MOF的导电性.进一步通过理论计算研究了肼在MnFc'和MnFc'-V表面的逐步脱氢过程,结果�The applications of metal-organic frameworks(MOFs)in electrocatalysis are limited by the perfect crystalline nature with insufficient coordinatively unsaturated sites and low electronic conductivity.Here,we report an electrosynthesis method to induce rapid assembly of amorphous MOFs on carbon cloth(denoted as aMnFc'/CC),achieving the amorphization of MOFs with rich active sites and high electronic conductivity.The long-range disordered structure of aMnFc'/CC forms a large number of oxygen vacancies to modify the coordination and electronic structures of Mn sites.In the electrocatalytic hydrazine oxidation reaction(HzOR),the aMnFc'/CC electrocatalyst exhibits superior activity to its crystalline MOF counterparts.Density functional theory calculations reveal that the unsaturated Mn centers present in aMnFc'/CC facilitate efficient electron transfer while simultaneously lowering the free energy of the rate-determining step in the HzOR process.

关 键 词：非晶化 缺陷 电催化 肼氧化反应 金属有机框架 

分 类 号：TQ426[化学工程]