CeO2 crystal plane engineering to modulate CuO-CeO2 interactions and modify the CO-PROX reaction pathway

Abstract

Adjustment of the CeO2 exposed planes is an effective tool for modifying the metal-support interaction, which is the basis for the excellent CO preferential oxidation (CO-PROX) performance of CuO/CeO2 catalysts. However, the relationship between the CeO2 exposed planes, CuO-CeO2 interaction and reaction performance is still unclear. Herein, we investigated the effect of interactions on the structure of CuO/CeO2 catalysts and the CO-PROX reaction by modulating the CeO2 exposed planes (CuCe-NC (nanocubes) exposed {100} planes and CuCe-NP (nanoparticles) exposed {111} planes). The results indicate that the {100} plane exhibits greater CuO dispersal capabilities due to electron transfer caused by stronger interactions produces an anchoring effect on CuO. This promotes increased contact between CO and CuO during the reaction, creating more CO adsorption sites and improving low temperature activity. Furthermore, effective electron transfer between CuO and {100} planes during reaction maintains Cu+ stability while widening the temperature window. In-situ spectroscopy and DFT calculations showed that the Cu+–CO bond strength is weakened by the enhanced interaction, which together with the excellent surface structure of CeO2-{100}, favours the direct desorption of CO2. However, forming carbonate on CuCe-NP seems to be preferable. Various CO-PROX reaction pathways are suggested for different exposed crystal planes. This insight into crystal plane effects on CO-PROX may guide the design of high-performance catalysts.