微纳结构类石墨烯MXenes相多孔材料的可控制备及析氢行为研究

The traditional electrolytic water hydrogen evolution material exists in the form of powder, relying on the polymer binder to load it on the conductive substrate. Sometimes, the active catalytic sites are covered by polymer binder, and, they could be dropped out easily under the operation of large current test due to bubble generation. To overcome this difficulty, this project aims to fabricate a micro-nano-MXenes porous materials with good chemical stability and high catalytic activity. Specific contents are as follows: (1) The micrometer scale TiVAlC porous materials with controlled pore structure were prepared by TiH2, V, Al and graphite powder. The effects of sintering temperature, sintering time, Al content, particle size on porosity were investigated by DSC, XRD, SEM and pore size tests. The pore-forming mechanism was explored relying on the pore structure analysis. (2) Micron-sized TiVAlC porous material is as the matrix, TiVCTx (Tx = OH, O, H) porous materials were prepared by sol- etching method and ultrasonic etching technique. With XRD, SEM and XPS analysis, the effects of etch temperature, time and ultrasonic power on the etching products were studied, and the mechanism of solvent etching was also illustrated. (3) The mechanism of hydrogen evolution under the nanoscale structure was discussed by using the electrochemical test technique, SEM, XPS, XRD, Raman spectroscopy and other analytical methods.

电解水析氢材料通常以粉末形式存在，依靠粘结剂负载于导电基底上，覆盖了活性催化位点，且在大电流操作下易造成活性点位脱落和丢失。为克服这一困难，本项目旨在制备一种化学稳定性好、催化活性高的微纳结构MXenes相多孔材料。内容包括：（1）以TiH2、V、Al、石墨粉末为原料，真空烧结制备孔隙结构可控的TiVAlC多孔材料，运用DSC、XRD、SEM、孔径测试等手段考察烧结温度、时间、Al含量、粉末粒度对孔隙结构的影响，探讨反应造孔机制。（2）以TiVAlC多孔材料为基体，选用溶剂刻蚀法，辅助超声刻蚀，制备类石墨烯TiVCTx（Tx= OH, O, H）多孔材料，采用XRD、SEM、XPS、拉曼、ICP等分析技术研究刻蚀温度、时间、超声功率对刻蚀产物的影响，探讨刻蚀机理。（3）综合运用电化学测试技术和XRD、SEM、XPS、拉曼光谱等分析形貌、物相结构及析氢性能，探讨纳米尺度结构下的析氢作用机理。

Mxene作为一种类石墨烯结构的过渡金属碳化物，因其具有过渡金属和表面官能团结构，显示出独特的导电性能和极低的氢吸附自由能，在析氢催化领域激发了广泛的研究兴趣。目前，MXene析氢性能研究大部分停留于理论计算，实验研究较少，电催化析氢机理研究尚不够深入。本项目提出设计、制备一种微纳结构的类石墨烯多孔材料，并研究其析氢性能。研究内容主要分为三部分：（1）以TiH2、V、Al、石墨为原料，采用模压成形-活化反应烧结制备 TiVAlC多孔材料基体，通过调控粉末粒度、活化反应物质Al含量、压制压力和烧结温度，控制基体孔隙结构和形貌，探讨烧结动力学-物相转变-孔隙结构耦合作用机制。（2）以 TiVAlC粉末为原料，以HF为刻蚀剂，调控刻蚀温度和时间，通过对刻蚀产物的物相组成，微观形貌，元素价态及分布等情况的研究，阐明了MXene的微观结构，明确了合成条件与材料结构特征之间的调控规律。（3）通过N-甲基吡咯烷酮，KOH对刻蚀产物进行表面改性，并与泡沫镍进行复合，结果表明该复合材料显示出较低的析氢过电位和优异的析氢催化活性。通过对上述内容的研究，分析了析氢电极材料“成分-结构-性能”三位一体的作用机制，构建了材料结构特性与析氢性能之间的“构效关系”。