In this review, we critically discuss the recent advances, developments and remaining challenges and future development on photocatalytic application of well-defined hybrid Cu ₂ O nanostructures for organic reactions, H ₂ evolution and CO ₂ reduction.

Syntheses of metal and oxide nanocrystals with cubic crystal structures and well-controlled polyhedral morphologies such as cubic, octahedral, and rhombic dodecahedral shapes exposing, respectively, {100}, {111}, and {110} surfaces enable a more accurate determination of their facet-dependent properties. So far molecular adsorption, photocatalytic, organocatalytic, and electrical conductivity properties have been demonstrated to be surface-related or facet-dependent. Chemical etching and metal nanoparticle deposition can also be face-selective. Examples of these surface properties are presented. In general, ionic solids such as Cu₂O nanocrystals exhibit more sharply different surface properties than those seen in metal nanoparticles. A better understanding of these facet-dependent properties is necessary to prepare nanomaterials with enhanced properties such as their catalytic activities.