Mechanistic Study of Low-Temperature Co Oxidation Over Cuo/Cu2o Interfaces with Oxygen Vacancy Modification

Abstract

Copper oxides have attracted great attention in oxidation of CO due to its high activity at low temperature. In this work, a novel CuO/Cu 2 O heterojunction catalysts for low-temperature CO oxidation was prepared via hydrothermal in-situ oxidizing in H 2 O 2 . Based on studies of surface composition and the corresponding catalytic activities, the CC catalysts contains rich oxygen vacancies, which improve the activation and migration ability of O 2 . The coupling effect between oxygen vacancies and heterojunction also reduces the activation energy of CO oxidation, leading the temperature of CO completed oxidation temperature from 250 o C to 140 o C. In addition, the in-situ Fourier transform infrared spectroscopy (in-situ FTIR) and Density functional theory (DFT) studies both confirms two reaction paths under Langmuir-Hinshelwood (LH) mechanism with different reaction energy of 0.181eV and 1.8eV, attributed to a new reaction sites at the CuO/Cu 2 O interface lead to different activation modes of CO and O 2 . The formation of oxygen vacancies significantly reduces the reaction temperature required. This work provides a method to improve the performance of co-catalytic oxidation via the coupling effect of oxygen vacancies and heterojunctions.

Keywords: Microsphere, Copper oxide, CO oxidation, heterojunction, Oxxygen vacancy