【作者】 高杨；

【导师】 于广涛；

【作者基本信息】 吉林大学 ， 物理化学， 2021， 硕士

【摘要】 自工业革命以来,化石能源一直是世界能源供应的主要来源。然而,其过度使用已经引起了能源枯竭,并且对环境造成了非常严重的污染,这促使全世界各国都在积极寻找廉价、可靠和清洁的新型能源。氢气以其能量密度高、资源丰富、无污染的特点,正成为取代传统化石燃料的理想绿色能源。电化学水解离技术不仅生产氢效率高,而且纯度高、无污染,比许多其他技术更具有实用性。然而,电催化析氢反应（HER,2H⁺+2e^-=H₂）是一个缓慢的动力学过程,因此开发廉价高效的析氢催化剂已经成为电解水制氢技术大规模实施的关键。基于密度泛函理论（DFT）模拟,我们系统研究了二维单层Cu₂X（X=Si和Ge）体系的结构和析氢催化活性。计算结果发现,单层Cu₂X（X=Si和Ge）可以呈现出良好的HER催化活性,X（X=Si和Ge）原子上方是析氢催化反应的最佳活性位点。进一步,我们提出引入单空位缺陷（尤其在Cu₂X中引入X缺陷）可以作为一个有效策略去显著提高Cu₂X（X=Si和Ge）的表面析氢催化活性。其后,我们分别对纯的和引入单空位缺陷后的Cu₂X（X=Si和Ge）体系进行了不同氢覆盖率下的HER催化活性的研究,发现这些体系均能在一个宽的氢覆盖率范围内依然保持优异的HER催化活性。此外,计算结果也表明Cu₂X（X=Si和Ge）体系具有良好的导电性和结构稳定性,这对析氢催化性能也是十分有利的。因此,这些二维纳米材料非常有希望成为廉价高效HER催化剂的优秀候选者。总之,这项工作能为基于二维Cu₂X（X=Si和Ge）纳米体系的廉价高效HER电催化剂的设计和实际应用提供有价值的理论指导。更多还原

【Abstract】 Since the industrial revolution,fossil energy has been the main source of world energy supply.However,its excessive use has caused energy depletion and serious environmental pollution,which prompted all countries in the world to actively seek cheap,reliable and clean new energies.Hydrogen is an ideal green energy to replace traditional fossil fuels because of its high energy density,abundant resources and no pollution.Electrochemical water-splitting technology is not only efficient in hydrogen production,but also has high purity and no pollution,which is more practical than many other technologies.However,considering that electrocatalytic hydrogen evolution（HER,2H⁺+2e^-=H₂）is a slow kinetic process,the development of cheap and efficient hydrogen evolution catalyst has become the key to the large-scope application of hydrogen production technology from electrolytic water.Based on DFT calculations,we systematically study the structure and hydrogen evolution catalytic activity of the two-dimensional（2D）Cu₂X（X=Si and Ge）system.The results show that the Cu₂X（X=Si and Ge）monolayer can show good HER catalytic activity,where the top of X atom can act as the best active site.Moreover,we have proposed an effective strategy through introducting a monovacancy（especially X defects in Cu₂X）to further improve the HER activity of the 2D Cu₂X system.This is mainly due to the fact that the defect reduces the coordination number of the surrounding atoms,which not only improves the activity of the original active sites,but also produces many new active sites.Further,we performed computations on theΔG_H*values as a function of varying hydrogen coverage for the pure and defective Cu₂X systems.It is found that these systems can maintain excellent HER catalytic activity in a wide range of hydrogen coverage.In addition,our computed results also show that Cu₂X（X=Si and Ge）system has good conductivity and structural stability,which is also very beneficial to hydrogen evolution catalytic performance.Therefore,these two-dimensional nanomaterials are very promising to be excellent candidates for low-cost and high-efficiency HER catalysts.In a word,these foundings can provide valuable theoretical information for the design and practical application of cheap and efficient HER electrocatalyst based on the two-dimensional Cu₂X（X=Si and Ge）systems.更多还原