Recent advances on catalytic potentials of copper oxides (I & II): fundamentals to applications

Amid the ongoing energy and environmental crises, identifying sustainable solutions is essential. Catalysis emerges as a promising approach to address issues related to fossil fuels, decrease reliance on them, and promote clean energy processes like hydrogen production, CO₂ reduction, and pollutant elimination. Copper oxide (I and II), a semiconductor with significant catalytic potential, has attracted considerable research interest owing to its unique properties. This review explores the diverse nature of copper oxide, emphasizing its role as a p-type semiconductor, which is vital to material science. As one of the earliest known semiconductors, it exhibits a direct bandgap between 1.2 eV and 2.20 eV. Copper oxide’s advantages in catalysis include its nontoxicity, affordability, abundance, narrow band gaps, high stability, and strong visible light absorption. The review highlights recent advances in synthesis techniques such as irradiation, electrodeposition, sputtering, solvothermal/hydrothermal methods, green synthesis, and coprecipitation, enabling precise control over nanoparticle size, shape, and properties. In photocatalysis, Cu₂O/CuO heterojunctions (e. g., p-n, Z- Z-scheme) and composite materials achieve exceptional hydrogen production by reducing charge recombination and photo-corrosion. For CO₂ reduction, Z- scheme systems enhance efficiency and stability, leading to hydrocarbon formation. Pollutant breakdown is improved by doped composites that boost activity and reusability. Electrocatalytically, copper oxide hybrids and doped composites demonstrate low overpotentials and high stability, rivaling noble metals for hydrogen evolution. In CO₂ electrocatalysis, features like crystal facet engineering and the addition of carbon-based materials (e. g., graphene) improve selectivity. By overcoming synthesis challenges and optimizing material designs, copper oxide nanostructures hold significant potential for renewable energy, environmental cleanup, and sustainable development-supporting scalable green hydrogen production and CO₂ utilization technologies.