中熵合金修饰MXene基高效电催化析氢催化剂的构筑及机理研究

The development of low-cost, high-activity electrocatalytic hydrogen evolution reaction (HER) catalysts based on non-precious metals has been a hot topic in the study of industrial-scale hydrogen production. MXene is a kind of novel two-dimensional (2D) material with the left-hand side transition metal-carbide/nitride characters, which has important potential applications in the field of electrochemical energy storage and conversion. However, the MXene usually presents an inferior intrinsic HER activity. At present, doping and surface modification are the two popular directions in this field. In consideration of the unique surface left-hand side transition metal atomic layer in MXene, this project intends to introduce right-hand side transition metal via an alloying method, and constructs 2D heterostructure with medium-entropy alloy on its surface. Through the hybridization of d-electrons from both left- and right-hand side transition metals, the competitive adsorption of catalytic intermediate products under alkaline condition can be regulated. Meanwhile, the MXene nanosheets can provide good electron transmission and ion diffusion pathway, and serve as the substrate to provide nucleation sites, limit the agglomeration of alloy nanoparticles. As a result, the designed structure will synergistically promote the kinetic of electrocatalytic HER process. By studying the formation process of medium-entropy alloy on the surface of MXene and the activities regulation law of electrocatalytic HER, this project will provide ideas for the design and performance control of low-cost, high-efficiency catalysts towards industrial-scale hydrogen production.

开发基于非贵金属的低成本、高活性电催化水分解析氢催化剂一直是工业化规模电解水制氢研究的热点。迈克烯（MXene）是一类具有左侧过渡金属-碳/氮化合物结构特征的新颖二维材料，在电化学能源存储和转化领域有着重要应用潜力，但是其本征电催化析氢活性较低。目前，对MXene材料进行掺杂和表面修饰是该领域研究的两个热点方向。针对MXene独特的表面左侧过渡金属原子层结构，本项目拟利用合金化方法引入右侧过渡金属，构筑中熵合金修饰的二维异质结构，通过左右两侧过渡金属的d电子杂化，调控碱性析氢条件下各催化中间产物的竞争吸附。同时，该异质结构中MXene纳米层可以提供良好的电子传输和离子扩散通路，并作为衬底提供形核位点、限制合金纳米颗粒的团聚，进而协同促进电催化析氢动力学过程。通过研究中熵合金在MXene表面的形成过程及电催化析氢活性调控规律，将为实现廉价高效的工业化电解水制氢提供材料设计和性能调控思路。

开发基于非贵金属的低成本、高活性电催化水分解析氢催化剂一直是工业化规模电解水制氢研究的热点。本项目围绕MXene表面合金复合电催化剂作为研究对象，通过不同前驱物及反应条件的优化，获得了系列具有可控电催化活性的复合电催化剂，并在电催化水分解析氢领域着重开展了研究。课题主要取得的成果如下：（1）成功制备了系列具有可变金属比例的双金属MXene材料,如V3CrC3Tx、V2Cr2C3Tx、Mo2TiC2Tx等，并用于负载合金纳米颗粒制备复合电催化剂;（2）利用双金属前驱物结合MXene表面金属,获得了具有中熵成分的合金产物，并探究了该中熵合金复合电催化剂的电催化活性来源及影响机制；（3）揭示了了MXene在合金纳米颗粒复合电催化剂中的供电子特性,以及该作用对电催化析氢活性的影响机制,为后续电催化剂的设计提供了理论依据;（4）探索了除氢氧化物之外的前驱物（如金属配位聚合物）在MXene表面的负载与合金转化过程,获得了相应电催化剂材料并进行了性能优化,阐明了合金的相形成及转变与电催化性能的构效关系。通过研究中熵合金在MXene表面的形成过程及电催化析氢活性调控规律，本项目建立了MXene负载合金纳米结构的创新方法,并阐明了催化性能的构效关系模型，为实现廉价高效的工业化电解水制氢提供材料设计和性能调控思路。