Chemical control of cuprite crystal growth and morphology toward high-index surfaces

The morphology of cuprite (Cu2O) crystals is governed by the interplay among reduction chemistry, solution composition, nucleation kinetics, and selective stabilization of crystallographic planes during growth. In this work, these factors were systematically investigated through two wet-chemical precipitation routes employing either glucose or a poly(vinylpyrrolidone)/ascorbic acid (PVP/AA) system as reducing and crystal growth-directing agents. The glucose-mediated route showed a strong dependence on alkalinity and glucose concentration, producing a progressive evolution from octahedral to truncated octahedral, cubic, and complex polyhedral morphologies, exposing {100}, {110}, {111}, and high-index facets. In the PVP/AA system, decoupling the reducing and capping functions promoted the formation of rounded particles characterized by a dense arrangement of high-index facets, whereas octahedral crystals can also be obtained under specific conditions, demonstrating that the stabilization of {111} facets does not exclusively depend on glucose. Comparative experiments showed that PVP alone yielded CuO, whereas AA promoted Cu2O formation, highlighting the distinct roles of reduction and surface modification in the crystal growth. Overall, the results demonstrate that solution chemistry and selective surface interactions can be exploited to control Cu2O morphology and crystallographic facet exposure.