Highly dispersed Pt studded on CoOx nanoclusters for CO preferential oxidation in H2

Abstract

Carbon monoxide (CO) preferential oxidation (PROX) is regarded as a promising method for hydrogen purification. Herein, the design and synthesis of highly dispersed Pt studded on CoO_x catalysts are reported. The catalysts exhibit nearly 100% CO conversion and selectivity towards the CO PROX reaction under H₂ stream at room temperature. The superior catalytic performance can be attributed to the unique structure. The Pt is selectively studded on CoO_x nanoclusters to maximize the highly active metal–oxide interfaces. The Pt loading is reduced to ∼0.8%, which is one of the lowest reported loadings for Pt-based CO PROX catalysts. The kinetics studies reveal that the composite Pt–Co catalysts have a weaker CO adsorption and lower O₂ activation barrier, which can increase the CO oxidation rate and suppress the H₂ oxidation rate. In addition, it is found that the CoO_x promotor in a lower chemical oxidation state is critical for the improved activity. Theoretical simulations reveal that the energetic route of CO oxidation in H₂ for Pt/CoO is more active than that for a Pt/Co₃O₄ surface.