若干石墨烯基材料催化性能的理论研究

发布时间：2018-12-25 12:28

【摘要】：随着工业技术快速发展,化石能源消耗巨大,能源危机和环境污染问题日渐突出,清洁能源转换装置是解决相关问题的有效方法。燃料电池就是一种具有能源使用率高又不污染环境的能量转化装置。传统燃料电池阴极使用的Pt基催化剂,由于其昂贵的价格、低丰度、低耐久度以及CO中毒等问题,阻碍了其商业化的快速发展。相关实验和理论研究发现,非金属掺杂的石墨烯材料可以做为替代Pt基催化剂的潜在的新型电极催化剂。该文使用基于包含色散矫正的密度泛函理论(DFT-D)的第一性原理方法探索了硫掺杂石墨烯(SGV)上的氧还原反应(ORR)机理,以及硅和磷双掺杂石墨烯(Si-P-G)的直接合成过氧化氢(DSHP)的反应机理,主要研究工作及结果如下:1.通过基于包含色散矫正的密度泛函理论研究了SGV上的氧还原反应机理,并且给出了其动力学和热力学过程的全部细节。计算结果说明,SGV相当稳定,而且S掺杂剂做为潜在的活性中心。根据动力学过程分析,这里有两种ORR可能的路径:OOH解离过程和OOH加氢过程,对应的限速步分别为0.75 eV和0.62 eV。ORR过程的吉布斯自由能表明HOOH加氢是最佳路径,甚至在0.86 V的高电势下也可以进行。DFT-D计算表明SGV是催化ORR过程的高效催化剂。2.通过基于含色散矫正的密度泛函理论研究了Si-P-G上的氧还原反应机理。最稳定的Si-P-G构型中,掺杂剂区域对吸附和还原氧分子扮演了重要的角色。根据动力学和热力学分析,二电子路径是DSHP的还原过程。O_2加氢形成OOH是限速步,对应的势垒是0.66 eV。势能面通过计算吉布斯自由能给出。所有的结果表明Si-P-G是一个对DSHP具有高活性和高选择性的催化剂。
[Abstract]:With the rapid development of industrial technology, fossil energy consumption is huge, energy crisis and environmental pollution problems are increasingly prominent, clean energy conversion device is an effective method to solve the related problems. Fuel cell is a kind of energy conversion device with high energy efficiency and no pollution to the environment. Because of its high price, low abundance, low durability and CO poisoning, the traditional Pt catalyst used in the cathode of fuel cell has hindered the rapid development of its commercialization. Related experiments and theoretical studies show that nonmetal doped graphene can be used as a potential new electrode catalyst instead of Pt based catalyst. The first principle method based on density functional theory (DFT-D) including dispersion correction is used to explore the (ORR) mechanism of oxygen reduction over sulfur doped graphene (SGV). The mechanism of the direct synthesis of hydrogen peroxide (DSHP) from silicon and phosphorus double doped graphene (Si-P-G) is discussed. The main results are as follows: 1. Based on the density functional theory including dispersion correction, the mechanism of oxygen reduction on SGV is studied, and all the details of its kinetic and thermodynamic processes are given. The results show that SGV is quite stable and S dopant is the potential active center. According to the kinetic process analysis, there are two possible paths for ORR: OOH dissociation process and OOH hydrogenation process. The Gibbs free energy of the corresponding rate-limiting steps of 0.75 eV and 0.62 eV.ORR shows that HOOH hydrogenation is the best path. DFT-D calculations show that SGV is an efficient catalyst for the catalytic ORR process. Based on the density functional theory (DFT) with dispersion correction, the mechanism of oxygen reduction on Si-P-G was studied. In the most stable Si-P-G configuration, the dopant region plays an important role in the adsorption and reduction of oxygen molecules. According to the kinetic and thermodynamic analysis, the two-electron path is the reduction process of DSHP. The hydrogenation of O _ s _ 2 to OOH is a rate-limiting step with a corresponding barrier of 0.66 eV.. The potential energy surface is given by calculating Gibbs free energy. All the results show that Si-P-G is a catalyst with high activity and selectivity to DSHP.
【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

【相似文献】