镍钴基过渡金属包覆铜基纳米线阵列的构筑及电催化氧化丙三醇性能研究

Electrocatalytic water splitting is considered as a promising approach to produce hydrogen as clean and renewable fuel. However, its overall energy efficiency has been limited by the kinetically sluggish water oxidation reaction (WOR). Recently, the development of transition metal-catalyzed, novel anodic reactions which are able to realize the value-adding transformation of platform molecules has attracted considerable attention. Meanwhile, as the dominant by-product during the production of bio-diesel, glycerol can be oxidized to multiple platform molecules, however the feasible approach is yet to be developed. Based on the idea of utilizing biomass-derived glycerol, this project aims to employ Cu-based@Ni,Co-based transition metal compounds core@shell nanowire array as electrocatalyst to catalyze the thermodynamically favorable glycerol oxidation reaction with high selectivity towards valuable chemicals. The unique structure of nanowire array would expose high active surface area and benefit the mass transfer. This way the water oxidation reaction shall be avoided on the anode. With this project the controllable fabrication of structurally-stable core-shell nanoarrays will be achieved by tuning the experimental parameters; afterwards the as-prepared electrodes will be carefully characterized in order to gain information on the components, surface structure and redox property of catalytically-active species. Then the electrocatalytic performance and product selectivity towards glycerol oxidation will be evaluated, during which the in-situ infrared spectroscopy will be used to investigate the reaction pathway. The goal of this project is to establish the correlation between the component/structure of core-shell nanoarrays and the electrocatalytic activity towards glycerol oxidation to produce valuable chemicals. This work will provide theoretical guidance and practical basis for the design of novel electrolyzers realizing high-efficiency hydrogen generation from water coupled with biomass upgrading.

电化学分解水是具有前景的制氢途径，但其能量转化效率和经济性常被动力学迟缓的阳极水氧化反应所限制。为了解决这一问题，镍钴等过渡金属催化的可实现反应物增值的新型阳极反应的开发受到了广泛关注。作为生物柴油生产的副产物，丙三醇可被氧化为多种有价值的化学品，但目前尚缺少经济可行的手段。基于以上背景，本项目拟制备镍钴基过渡金属包覆的铜基纳米线阵列，利用其比表面积高、物质扩散便利等优点高效催化丙三醇的电化学氧化，以替代全解水过程中发生在阳极的水氧化反应。拟设计、制备核壳结构纳米阵列并结合表征手段和电化学方法对结构以及催化组分的氧化还原特性进行表征；考察上述因素对电催化氧化丙三醇活性和产物选择性的影响，并利用电化学原位红外技术阐述过渡金属催化丙三醇氧化的反应路径，建立组分和结构与电催化性能的构效关系。为构建可实现生物质资源增值利用的高效析氢电解体系、进一步提升电解水制氢效率提供理论指导和实践基础。

电化学分解水是具有前景的制氢途径，但其能量转化效率和经济性常被动力学迟缓的阳极水氧化反应（OER）所限制。为了进一步提高电解水制氢效率，近年来用以替代OER的新型阳极氧化反应的开发受到了广泛的关注。该类反应的热力学能垒通常较低，且有望实现增值化学品的高选择性制备。同时，丙三醇及5-羟甲基糠醛作为典型的生物质衍生平台分子，能够被氧化为甲酸或呋喃二羧酸等高价值的化学品。针对以上平台分子的电化学氧化，镍钴基过渡金属电催化剂展现出较为优异的催化活性。然而为了与实际应用中的大规模电解水析氢耦合，进一步提高其电催化剂活性迫在眉睫；在保证其催化活性与性能稳定性的同时，实现高附加值产物的高选择性制备也是需关注的要点。.在本基金的实施过程中，申请人针对高性能电极材料的制备及反应机理的阐述做了系统性的研究工作，具体成果包括：（1）开发了阳极氧化-硫化-电沉积的技术路线，在导电泡沫铜基底上制备了硫化铜@镍钴氢氧化物纳米阵列，其在5-羟甲基糠醛的电化学氧化中展现出优异的催化活性和选择性；（2）采用电化学活化实现了镍钴金属有机框架纳米片阵列向镍钴氢氧化物纳米阵列的原位转化，得益于其较高的表面面积及镍钴协同作用，该电极在多种生物质平台分子的选择性氧化中展现出较高的催化活性；（3）借助实验手段和理论计算揭示了电化学条件下不同氧化态的Co物种对5-HMF电化学氧化动力学和产物选择性的调控机理，即Co3+物种仅能催化5-HMF 中醛基的氧化但无法催化羟基的氧化，而Co4+则能催化羟基与醛基的氧化；（4）采用原位电化学还原法制备了金属钴纳米阵列。其作为活性组分在电化学还原硝酸盐制氨反应中展现出同期最优的催化活性和接近100%的制氨法拉第效率。.以上工作系统的探究了镍钴基过渡金属电极在生物质平台分子高选择性氧化中的应用，论证了以新型阳极氧化反应替代传统水氧化反应以提高电解水析氢过程中能源转化效率的可行性，同时其提出的反应路径对高性能电催化剂的开发具有积极的指导意义。