Evolution of a Cu₂O Cube to a Hollow Truncated Octahedron and Their Photocatalytic and Electrocatalytic Activity

The structure regulation of cuprous oxide (Cu2O) has been realized from submicrometric cubes to irregular hollow polyhedrons and hollow truncated octahedrons. It is suggested that the evolution of Cu2O exotic morphology and hollow structure are caused by an inside–out Ostwald ripening mechanism in the synthetic system, followed by the induced formation of eight (111) and six (100) planes of a hollow truncated octahedron, while a Cu2O cube with six (100) planes is formed quickly via directed attachment in a weak reduction environment. Photocatalysis of methyl orange indicated that the (111) planes of a hollow truncated octahedron showed higher catalytic activities than the (100) planes of both structures. However, both the (100) and (111) planes in a Cu2O cube or hollow truncated octahedron display high electrocatalytic activities toward the reduction of nitrobenzene. A glassy-carbon electrode modified by Cu2O hollow truncated octahedrons showed that the highest catalytic current was 401.8 μA with the most negative potential at −0.82 V due to the small size and hollow nature among these Cu2O particles. The formation of Cu2O cubes and hollow polyhedrons and their structure–property relationship have been studied on the basis of the experimental data.