Promotional effects of Cu x O on the activity of Cu/ZnO catalyst toward efficient CO oxidation

Highlights: • Interstitial substitution of Cu_xO into Cu/ZnO were successfully fabricated. • Cu in ZnO lattice acted as a bridge to accelerate the transfer of charge carriers. • Active Cu_xO on Cu/ZnO promoted redox properties and oxygen vacancies. • Cu_xO-Cu/ZnO granted good performance and stability in CO oxidation. Tailoring the configuration at metal and support interface contributes to an effective pathway for fabricating catalysts of high catalytic performance for scientific and industrial applications. In this study, the CO oxidation activity over spray-pyrolyzed copper doped Zinc oxide (Cu/ZnO) catalyst was enhanced by deposition–precipitation of 1 wt% Copper (Cu_xO-Cu/ZnO). Copper ions substituted into ZnO caused defects which altered the physiochemical properties of the catalyst and acted as a bridge to accelerate the transfer of charge carriers to the surface, but the promoting effect of Cu_xO incorporated by deposition–precipitation elevated the catalytic performance of the catalyst. The activation energy of Cu_xO-Cu/ZnO (24.52 KJ mol⁻¹) was extremely lower than that of 20 wt% Cu/ZnO (32.19 KJ mol⁻¹) catalyst in CO oxidation due to the active and populous Cu(I) species in Cu_xO-Cu/ZnO. Defects created by the incorporation of Cu species in Cu_xO-Cu/ZnO catalyst contributed to low-temperature reducibility, oxygen mobility and abundant oxygen vacancies, which played fundamental role in enhancing the activity of Cu_xO-Cu/ZnO, compared its counterpart. The critical role of the active Cu⁺ sites was further confirmed by In-situ DRIFTS.