二维黄铁矿结构硫磷化钴的可控制备及其原位电催化析氢机理研究

New types of two-dimensional materials are expected to meet the design principles and the requirements of high catalytic activity, high specific surface area, large surface to volume atomic ratio and controllable chemical coordination bonding states for of high performance electrochemical catalysts. Low-cost pyrite-structured cobalt phosphosulfide nanostructures have been considered as the most promising catalysts to replacing the Pt group noble metals for electro-catalytic hydrogen production. However, due to the limitation of current synthetic methods for specific crystal orientation or morphology on this materials, the relationship between intrinsic structures and hydrogen production performance is unclear yet. Therefore, it is urgent to design and prepare a two-dimensional cobalt phosphosulfide with a specific structure and study its hydrogen evolution mechanism. We propose that using van der Waals epitaxial based chemical vapor deposition method to grow high-quality two-dimensional pyrite-structured cobalt phosphosulfide nano-plates with large domain size, controlled thickness and specific crystal orientation. Meanwhile, we will establish the fine structure characterization method for the 2D cobalt phosphosulfide catalysts to understand the surface/edge structure at atomic scale. The electrochemical micro-reactor based on the mirco/nano fabrication methods will be applied to study the structure-property relationships, in which the contribution of intrinsic catalytic active crystal planes/sites, catalysts conductivity and various interface will be discussed. This project can help the synthesis of non-layered two-dimensional phosphosulfide and provide the design principles for the high performance phosphosulfide based hydrogen production electro-catalysts.

新型二维材料有望契合高性能电化学催化剂的设计原则，可尽量满足对催化剂材料的高催化活性、高比表面积、大的表面原子比例、活性原子配位形态单一可控等的要求。黄铁矿结构硫磷化钴纳米材料已成为最有希望取代Pt族贵金属的廉价电化学析氢催化剂。然而，限于特定结构的硫磷化钴材料的制备现状，其析氢性能与材料结构等的构效关系尚不明确。设计制备具有特定结构的二维硫磷化钴并原位研究其氢析出机理迫在眉睫。我们提出基于范德华外延的二维黄铁矿结构硫磷化钴材料的化学气相沉积可控制备，制备高质量大尺寸、特定晶面晶向、厚度可控的二维黄铁矿结构硫磷化钴材料。建立表征晶体结构、表面原子排布的研究方法，理解催化剂的表面与边缘精细结构。基于微纳加工技术构筑电化学微反应器，研究析氢性能与活性晶面/位点、本征导电性及表界面结构的构效关系。本项目的开展有助于提高非层状磷化物材料的二维结构制备水平与总结概括出高性能磷化物电催化剂的设计原则。

二维材料当前已成为高性能电催化剂的有力候选体系，在于其催化活性高、比表面积高、活性原子配位形势多样。而黄铁矿结构的硫磷化钴化物材料，已表现出非常高的活性剂大面积制备的可能性，然而其催化位点及性能与结果之间的构效关系尚不清楚。.本项目采用化学气相沉积范德华外延生长方法，优化多种Co、S等前驱体工艺及动力学参数，兼容次亚磷酸钠温和磷化工艺，制备出高质量大尺寸（50 μm）、特定晶面晶向、厚度可控（低至7 nm）的二维Co基硫磷化物材料，同时拓展了在氧化硅/硅、蓝宝石等衬底上的厚度控制、覆盖度控制等生长。采用高分子聚合物薄膜辅助转移方法，可将样品转移至任意衬底，方便多种表征技术的开展。通过透射电子显微镜、X射线光电子能谱、X射线衍射等表征出所制备材料的晶体结构、化学组成、及表面与边缘原子结构。最终，基于探针台与电化学测试设备联用搭建了微纳电化学反应器件的测试平台，最低测试电流可低至10pA，圆满完成了表征不同表面与晶向的纳米片的电化学析氢性能测试。本项目的研究有助于提高非层状磷化物材料的二维结构制备水平与总结概括出高性能磷化物电催化剂的设计原则。