Effects of precursor concentration on morphologies of Cu2O micro/nanocrystals and properties of CO self-sustained catalytic combustion

Abstract

The self-sustained catalytic combustion is one of the most effective ways to remove high concentration CO at low temperature. In this paper, Cu2O micro/nanocrystals with different morphologies were successfully synthesized by changing the precursor concentration using liquid phase reduction method. The obtained Cu2O were characterized using SEM, XRD, XPS, H2-TPR and O2-TPD, and the relationship between the catalytic performance and morphology was analyzed based on CO-TPD-MS and activity evaluation results. It was found that high precursor concentration leads to more exposure of active crystal planes of Cu2O. Compared with Cu2O-1 exposing only (100) crystal planes, Cu2O-5, the precursor concentration of which is 5 times of Cu2O-1, exposes (100) and (110) crystal planes. Cu2O-9, with 9 times of precursor concentration of Cu2O-1, exposes (100), (110) and (111) crystal planes simultaneously. All the obtained Cu2O with different precursor concentrations can achieve self-sustained CO catalytic combustion, and the catalytic activity increases with increasing precursor concentration (Cu2O-1 < Cu2O-5 < Cu2O-9). The results prove that unsaturated coordination of Cu and O on the (111) and (110) planes can enhance the corresponding reducibility, adsorption and activation of gaseous oxygen, consequently promoting the CO oxidation to CO2 over Cu2O-9.