单层二硫化钼表面金属铂的可控掺杂及对该复合体系电催化析氢反应的研究

Electrocatalytic splitting of water is one of the most efficient and eco-friendly approach to generate hydrogen. Two-dimensional (2D) layered molybdenum disulfide (MoS2) has been considered as a promising candidate of the future electrochemical hydrogen evolution reaction (HER) catalyst due to its high catalytic activity on edges, the planar structure with the ultrasmall thickness which is easy to modify, and its abundant reserves on the earth. However, the HER performance of 2D MoS2 is still not as good as the noble metal Pt, and this has prompted investigations into hybrid Pt-MoS2 systems with suitable structures, which can make a good balance between the high catalytic activity and the low cost. This project will first study the controllable doping of Pt to monolayer MoS2. By making use of the unique interaction between Pt atoms/nanoparticles with defects on MoS2, the controllable Pt doping is intended to be achieved by first introducing various defects into monolayer MoS2 with a good controllability, followed by doping the defective MoS2 with Pt. The dispersion degree, structure and concentration of Pt on monolayer MoS2 will be controlled effectively using this method by carefully modifying the configuration and number of defects on MoS2. Secondly, state-of-the-art transmission electron microscopy will be applied to resolve the detailed configuration of Pt atoms/nanoparticles on defective MoS2. Finally, the electrochemical HER performance will be measured. The synthesis strategy and the structure of Pt-MoS2 corresponding to the sample with the best catalytic performance will be found out. Insights into the catalytic mechanism for different structured Pt-MoS2 will be obtained, which will deepen the understanding of the electrochemical HER procedure for metal-doped 2D material systems.

电催化分解水是制备氢气最高效、环保的方法之一。二维层状MoS2以其边界催化活性高，超薄平面结构易被改性，材料储量丰富等特点，成为新型析氢电催化剂的良好候选材料。然而，由于MoS2的催化活性仍不及贵金属Pt，这促使研究者探索通过将MoS2与Pt有效结合，获得兼顾催化活性与成本的Pt-MoS2复合催化剂。本项目拟研究金属Pt在单层MoS2表面的可控掺杂。利用Pt原子和纳米颗粒与MoS2表面缺陷的独特相互作用，在被可控引入缺陷的单层MoS2表面掺杂Pt，实现对Pt在MoS2上分散程度、掺杂结构和掺杂浓度的有效控制。同时，本项目还将运用先进的透射电子显微术，对Pt在有缺陷单层MoS2表面的掺杂形貌进行精细表征，并结合电催化性能的测试，确定效果最佳的Pt-MoS2催化剂所对应的结构与制备工艺，理解Pt-MoS2体系的催化机理，促进对金属掺杂二维材料复合体系电催化过程的认识。

电解水制氢气是高效清洁的能源产生方式之一。二维Mo基硫族化合物（如MoS2、MoTe2）具有超高的比表面积、高催化活性的边界和缺陷、储量较为丰富，易于被掺杂改性等特点。因此，将其作负载材料与Pt等异元素有效结合，制备诸如Pt-MoS2的二维复合体系是实现新型低成本、高催化活性析氢电催化剂的有效途径。本项目在CVD制备的单层MoS2通过等离子刻蚀方式预先引入空位缺陷，利用空位对Pt的锚定效应，实现了Pt纳米颗粒在MoS2表面的稳定，高分散掺杂。电催化性能测试显示，负载量仅为5 wt%的Pt掺杂单层MoS2表现出良好的催化性能，Tafel斜率为49 mV/dec，与含Pt量为20wt%的商用铂碳催化剂性能近似，3000次循环后性能仍保持较好稳定性。. 此外，本项目还紧跟学界发展前沿和实验中观测到的新奇现象，拓展性的开展二维2H-MoS2、1T’-MoTe2和低对称性ReS2的制备、缺陷的原子级结构和电子能带与断裂力学研究。具体成果包括：（1）创新开发了碱土金属盐辅助CVD法制单层备2H-MoS2，提出了酸碱匹配的促进机理，并对MoS2进行了空位和Te原子的掺杂，空位掺杂的MoS2也表现出良好的HER活性，Tafel斜率可达39 mV/dec；（2）开发了限域CVD法制备出大面积，尺寸达到80-100 μm的单层1T’-MoTe2。并针对该材料在含氧条件下的低稳定性，开发出用CVD批产的单层MoS2对1T’-MoTe2的封装策略，使1T’-MoTe2在空气中的寿命从数分钟延长至24小时以上。（3）用CVD法制备出具有低晶格对称性，各向异性理化性质的单层ReS2。利用埃米分辨的球差矫正扫描透射电镜，系统解析了所制备单层多晶ReS2中存在的重叠晶界、键合晶界等缺陷结构，结合密度泛函理论计算和原位电镜实验，研究不同结构晶界处的断裂力学性质和电子能带结构的各向异性。. 上述工作发表于Matter , Chem，Small, ACS Nano，Nanoscale等期刊，授权专利2项。以上成果深化对二维材料制备、原子级缺陷结构以及催化、电子能带和断裂力学性质的认识，推动了它们在能源、柔性器件等领域的应用。