Fabricating Cu2O-CuO submicron-cubes for efficient catalytic CO oxidation: The significant effect of heterojunction interface

Abstract

In this work, the uniform Cu2O submicron-cubes were facilely synthesized by liquid phase reduction method. Then, the Cu2O submicron-cubes were further oxidized into Cu2O-CuO heterojunction with tunable Cu2+/Cu+ ratios and CuO submicron-cubes by controlling the calcination temperature. The phase transition period during calcination was real-time monitored by the in-situ XRD and in-situ DRIFTS. The obtained materials were investigated as the catalysts of CO oxidation. The results revealed that the Cu2O-CuO heterojunction catalysts performed much higher catalytic activities than the Cu2O and CuO counterparts. Because the synergistic effect of the heterojunction (Cu2+/Cu+) could increase the surface oxygen vacancy concentration. Furthermore, it was also found that only the Cu2O-CuO heterojunction structure with the appropriate Cu2+/Cu+ ratio behaved the optimum catalytic activity. The kinetic studies indicated that the apparent activation energy of CO oxidation was greatly affected by the Cu2+/Cu+ ratio. Therefore, these Cu2O-CuO submicron-cubes with heterostructure were considered as the promising CO oxidation catalysts.