Photothermal CO-PROX reaction over ternary CuCoMnOx spinel oxide catalysts: the effect of the copper dopant and thermal treatment

Abstract

The purification of carbon monoxide in H₂-rich streams is an urgent problem for the practical application of fuel cells, and requires the development of efficient and economical catalysts for the preferential oxidation of CO (CO-PROX). In the present work, a facile solid phase synthesis method followed by an impregnation method were adopted to prepare a ternary CuCoMnO_x spinel oxide, which shows superior catalytic performance with CO conversion of 90% for photothermal CO-PROX at 250 mW cm⁻². The dopant of copper species leads to the incorporation of Cu ions into the CoMnO_x spinel lattice forming a ternary CuCoMnO_x spinel oxide. The appropriate calcination temperature (300 °C) contributes to the generation of abundant oxygen vacancies and strong synergetic Cu–Co–Mn interactions, which are conducive to the mobility of oxygen species to participate in CO oxidation reactions. On the other hand, the highest photocurrent response of CuCoMnO_x-300 also promotes the photo-oxidation activity of CO due to the high carrier concentration and efficient carrier separation. In addition, the in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) confirmed that doping copper species could enhance the CO adsorption capacity of the catalyst due to the generation of Cu⁺ species, which significantly increased the CO oxidation activity of the CuCoMnO_x spinel oxide. The present work provides a promising and eco-friendly solution to remove the trace CO in H₂-rich gas over CuCoMnO_x ternary spinel oxide with solar light as the only energy source.