氧化铜表面臭氧分解路径及表面氧物种生成机理研究

基于密度泛函理论（DFT）计算研究了O3在完整和具有氧空位的CuO(111)表面吸附的吸附位、吸附结构、吸附能和电子转移情况，比较了O3在完整表面和具有氧空位的表面分解的路径和能垒，分析了氧空位和表面吸附氧的生成机理。结果表明，在完整CuO表面，O3分子通过化学吸附或物理吸附表面结合，吸附能最高为-1.22eV（构型bri(2)）。O3在具有氧空位的CuO表面均为化学吸附，吸附能最高为-2.95eV（构型ovbri(3)），显著高于完整表面的吸附能。O3吸附后，Cu吸附位的电荷密度减小，O3中的O原子附近的电荷密度显著增强，电荷从CuO表面转移到O3，并形成Cu-O离子键。O3分解后形成了超氧物种，提高了表面的氧化活性。在完整表面，以构型bri(2)为起始构型的路径反应能垒最低，为0.52eV；O2*在完整表面的脱附所需要的最低能量为0.42eV，形成氧空位的O2*脱附能为2.06eV。在具有氧空位的表面，O3分解的反应能垒为0.30eV（构型ovbri(1)）和0.12eV（构型ovbri(3)），均低于完整表面的反应能垒；分解形成的O2*的最低脱附能也低于完整表面，为0.27eV。可见，氧空位的形成提高了吸附能，降低了反应能垒，使O3分子更容易吸附在CuO表面，并加快了O3的催化分解。

Mechanism of Ozone Decomposition and Oxygen Species Formation on Copper Oxide Surface

O3 adsorption and decomposition on CuO(111) surfaces with and without oxygen vacancies were studied by density functional theory (DFT) calculations. The decomposition pathway, reaction barriers and the formation of oxygen vacancies and the surface adsorbed oxygen were analyzed. On the intact CuO surface, O3 molecules interact with surface by physical or chemical adsorption, and the highest adsorption energy is -1.22 eV (structure bri(2)). On the surface with oxygen vacancy, O3 is chemically adsorbed and the highest adsorption energy is -2.95 eV(structure ovbri(3)), which is significantly higher than that on the intact surface. After O3 adsorption, the charge density near Cu adsorption site decreases, the charge density near O atom in O3 increases significantly, indicating that the charge transfer is from CuO surface to O3 and Cu-O ionic bond is formed. Superoxygen species are formed after O3 decomposition and the oxidation activity of the surface is improved. On intact surface, the reaction path starting from bri(2) has the lowest activation energy (0.52eV). The minimum energy for O2* desorption from the intact surface is 0.42 eV and the O2* desorption energy to form oxygen vacancy is 2.06 eV. The activation energies of O3 decomposition on the surface with oxygen vacancy are 0.30eV (ovbri(1)) and 0.12eV (vbri(3)), which are both lower than that of intact surface. The minimum desorption energy of O2* from the surface with oxygen vacancy is 0.27 eV, also lower than on intact surface. The results indicate that the formation of oxygen vacancy improves the O3 adsorption energy and reduces the activation energy and O2* desorption energy. Therefore, O3 molecule is easier to adsorb on CuO surface with oxygen vacancy and has higher reaction rate in catalytic decomposition of O3.