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  A highly dispersed CuO nano-island anchored Pt catalyst was designed and prepared.

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  Pt0.5-CuO5/HMS exhibited 100 % CO conversion (<0.2 ppb) at 110 °C in CO-PROX.

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  No inactivation was observed for Pt0.5-CuO5/HMS after 100 h of stability testing.

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  The adsorption and activation of CO tends to occur at the Pt-CuO interface.

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  The reaction energy barriers of H2 on the Pt-CuO interface increased six times.

In this paper, a highly dispersed CuO nano-island anchored Pt catalyst is designed and successfully prepared by selective electrostatic adsorption method. It is found that the nano-island catalyst exhibited excellent performance and stability in the CO preferential oxidation reaction. 100 % CO conversion and 50 % CO2 selectivity are achieved at 110 °C and no indication of decreased efficiency is observed within 100 h. The CO2 selectivity is constant over the entire temperature range. The characterizations and theoretical calculations are used to investigate the reaction mechanism. The results show that H2 oxidation tend to occur at the upper surface of Pt clusters which are loaded on the CuO nano-island, whereas the CO oxidation tend to occur at the interface of Pt-CuO. Compared with Pt-Cu bimetallic catalyst, the interface structure of Pt-CuO has been proved to enhance the adsorption and activation of O2 as well as reduce the energy barrier of CO oxidation from 0.28 eV to 0.01 eV.