氧气在碳化钨负载的铜-金合金单层上吸附与解离的第一性原理研究

采用基于密度泛函理论的第一性原理方法研究了碳化钨负载的铜-金合金单层催化剂对氧气吸附和解离性质的影响.通过比较碳化钨负载的纯金单层与铜掺杂的合金单层的电荷布局,发现掺杂铜可以创造新的活性位点,改变氧气的吸附构型,改善氧气的吸附和解离性质.进一步探究了氧气在Cu₁Au₈/WC(0001),Cu₂Au₇/WC(0001)上的解离过程,发现:氧气在Cu₂Au₇/WC(0001)上解离势垒仅为0.64 eV,远低于在纯金单层上的1.56 eV,表明铜掺杂有效促进了氧气的解离.铜掺杂后的单层结构变化预示了在单层产生了配位效应和局部应力效应.电荷布局和态密度结果表明铜掺杂促进了单层上电荷的重新分布,加强了氧气分子与基底的电荷转移和轨道杂化,从而增强了对氧气的吸附.当前的研究结果阐明了碳化钨负载合金单层对氧气分解的促进作用和机理,为设计更加高效廉价的氧还原反应催化剂奠定理论基础.

First-principles research of oxygen adsorption and dissociation on copper-gold alloy monolayer supported on tungsten carbide

Using the first-principles method based on density functional theory, the effect of copper-gold alloy monolayer supported on tungsten carbide on the properties of oxygen adsorption and dissociation are comparatively studied. Comparing the charge distribution of pure gold monolayer and gold monolayer doped with copper supported on tungsten carbide, it is found that copper doping is beneficial to enhance oxygen absorption and promote oxygen dissociation. We further explored the dissociation pathways of oxygen on Cu1Au8/WC(0001) and Cu2Au7/WC(0001), and found that the dissociation barrier of oxygen on Cu2Au7/WC(0001) is only 0.64 eV, which is much lower than that on pure gold monolayer (1.56 eV). This phenomenon indicates that copper substitution could effectively promote the dissociation of oxygen. The results of charge population and density of states show that copper doping could accelerate the redistribution of electrons on the monolayer, promote charge transfer and orbital hybridization between oxygen molecule and the substrate, thereby enhancing the adsorption of oxygen. The current research clarify the promotion effect and mechanism of the alloy monolayer on oxygen dissociation.