The properties, functions and application scenarios of copper oxide catalysts

I. Basic properties of copper oxide: a comprehensive analysis from structure to properties
(I) Chemical properties: the intrinsic relationship between oxidation state and reactivity
The chemical formula of copper oxide is CuO. The copper element exists in the +2 oxidation state. The crystal structure belongs to the monoclinic system. The oxygen atoms in its lattice are tightly packed, and the copper atoms are in a deformed octahedral coordination environment. This structure gives CuO unique electronic conduction properties - the top of the valence band is composed of O 2p orbitals, the bottom of the conduction band is composed of Cu 3d orbitals, and the band gap is about 1.2-1.5 eV (slightly different depending on the preparation method), which makes it exhibit excellent electron transfer ability in redox reactions.
As a catalyst, the chemical properties of copper oxide are mainly reflected in the following aspects:
Redox reversibility: the valence state conversion between Cu²⁺ and Cu⁺ (such as in the CO oxidation reaction) can effectively adsorb and release oxygen species to form active oxygen intermediates;
Surface acidity and alkalinity: the Lewis acid sites on the surface of CuO can adsorb molecules containing lone pairs of electrons (such as NH₃, CO), and the alkaline sites are suitable for the dehydration reaction of alcohol compounds;
Lattice oxygen activity: lattice oxygen can participate in the reaction at high temperature to achieve deep oxidation of the reactants (such as VOCs catalytic combustion).
(II) Physical properties: morphology and size determine catalytic efficiency
The physical properties of copper oxide are closely related to its preparation method. Common forms include powder, nanoparticles, nanowires, porous films, etc. Typical physical parameters are as follows:
Appearance and density: black or brown-black powder, density 6.3-6.4 g/cm³, melting point 1326℃;
Conductivity: The intrinsic state is semiconductor, and the conductivity is significantly improved after doping or nano-sizing (such as the quantum size effect of CuO nanoparticles);
Specific surface area: The specific surface area of ordinary bulk CuO is about 5-10 m²/g, while the specific surface area of nanoporous copper oxide can reach 50-100 m²/g, which greatly increases the number of active sites for catalytic reactions.
It is worth noting that the morphology of copper oxide has a significant effect on catalytic performance: the nanosheet structure is conducive to the planar adsorption of the substrate (such as benzyl alcohol oxidation), and the one-dimensional nanowire structure can optimize the electron transmission path (such as electrocatalytic CO₂ reduction).
II. The core role of copper oxide catalysts: from reaction mechanism to performance advantages
(I) The core mechanism of catalysis
The role of copper oxide as a catalyst can be summarized as a complete cycle of "reactant activation - intermediate conversion - product desorption", which is achieved through the following pathways:
Adsorption of active sites: Cu²⁺ sites have strong adsorption capacity for polar molecules (such as water and alcohols), reducing the activation energy of the reaction. For example, in the methanol synthesis reaction, the CuO/ZnO catalyst promotes the hydrogenation reaction with H₂ by adsorbing CO₂ molecules;
Electron transfer medium: In the oxidation reaction, the oxygen vacancies (defect sites) on the CuO surface can capture electrons to form active oxygen species (such as O⁻, O₂⁻), accelerating the oxidation process of the substrate (such as catalytic degradation of formaldehyde);
Carrier synergistic effect: When loaded on carriers such as Al₂O₃ and SiO₂, the interaction between copper oxide and the carrier (such as strong metal-carrier interaction, SMSI) can adjust its surface electronic structure and improve catalytic selectivity. For example, in the CO₂ methanation reaction, the CuO/γ-Al₂O₃ catalyst inhibits the occurrence of side reactions through the synergy between the carrier acid sites and the CuO active centers.
(II) Performance advantages compared to other catalysts
Compared with precious metals (such as Pt, Pd) or other metal oxides (such as MnO₂, Fe₂O₃), copper oxide catalysts have three core advantages:
Cost-effectiveness: copper is highly abundant in the earth's crust (about 0.01%), and the preparation cost is only 1/10~1/5 of that of precious metal catalysts;
Environmental friendliness: no heavy metal toxicity risk, the reaction products are mostly water and carbon dioxide, which conforms to the concept of green chemistry;
Temperature adaptability: efficient catalysis can be achieved under mild conditions (room temperature to 300℃), especially suitable for low-temperature waste gas treatment scenarios.
III. Multiple application scenarios: deep penetration from industrial catalysis to cutting-edge fields
(I) Environmental protection field: green treatment of waste gas and wastewater
Industrial waste gas purification: In the treatment of VOCs (volatile organic compounds) emitted by printing plants and chemical plants, copper oxide catalysts can catalyze the oxidation reaction of compounds such as benzene and toluene to generate harmless CO₂ and H₂O. For example, the conversion rate of toluene by CuO-CeO₂ composite catalyst at 200℃ can reach more than 90%, significantly reducing energy consumption;
Motor vehicle exhaust treatment: As an auxiliary component of the three-way catalytic converter, copper oxide can promote the reduction reaction of NOx and synergize with precious metals to improve the purification efficiency of NO and CO;
Catalytic oxidation in water treatment: In advanced oxidation processes (AOPs), CuO catalyzes H₂O₂ to generate OH radicals, degrading difficult-to-biodegrade organic pollutants (such as dyes and pesticide residues). Compared with traditional Fenton reagents, it can broaden the reaction pH range (3-9) and reduce the generation of iron sludge.
(II) Energy and Chemical Industry: Improved Efficiency of Synthesis and Conversion

Synthesis Gas Conversion: In methanol synthesis (CO₂+H₂→CH₃OH), CuO-ZnO-Al₂O₃ catalyst is the mainstream industrial system, and its activity comes from the adsorption and activation of CO₂ by Cu²⁺ and the dispersion and stabilization of Cu grains by ZnO;

Electrocatalysis and Energy Storage: Nano copper oxide as a battery electrode material can improve the lithium storage capacity of lithium-ion batteries (theoretical specific capacity reaches 674 mAh/g); in electrocatalytic CO₂ reduction, CuO nanocubes can highly selectively generate ethylene (C₂H₄), with a Faraday efficiency of more than 60%;

Hydrogen Energy Utilization: In the field of hydrogen purification, CuO catalyst can efficiently remove trace CO (<10 ppm) in hydrogen to avoid poisoning of Pt electrodes in fuel cells.
(III) Materials Science and Biomedicine: Innovative Applications of Nanocatalysis
Nanomaterial Preparation: Copper oxide can be used as a template or catalyst to control the preparation of materials such as one-dimensional carbon nanotubes and two-dimensional metal organic frameworks (MOFs). For example, CuO nanowire arrays can induce directional growth of graphene and improve the conductivity of composite materials;
Biocatalysis and Detection: In enzyme simulation studies, CuO nanoparticles exhibit peroxidase-like activity and can catalyze H₂O₂ to oxidize chromogenic substrates (such as TMB) for visual detection of glucose and DNA, with a cost of only 1/20 of that of natural enzymes;
Antibacterial Material Modification: Catalytic fibers or coatings loaded with copper oxide can effectively kill Escherichia coli and Staphylococcus aureus by releasing Cu²⁺ ions and catalyzing the generation of reactive oxygen species, and are suitable for surface treatment of medical devices.
Fourth, future development trends: technological breakthroughs from performance optimization to green preparation
At present, the research on copper oxide catalysts is deepening in the following directions:
Precise regulation of nanostructure: through hydrothermal method, atomic layer deposition (ALD) and other technologies, monodisperse nanoparticles, hollow structures or heterojunctions (such as CuO-TiO₂) are prepared to further improve the exposure rate of active sites;
Composite modification and synergistic effect: the introduction of a second component (such as Ce, Zr, Mn) to form a solid solution or core-shell structure to improve thermal stability and anti-poisoning ability (such as anti-sulfur and anti-chlorine performance);
Green preparation process: Develop microwave-assisted synthesis and bio-template method (using plant extracts to reduce copper ions) to reduce energy consumption and pollution, in line with the "dual carbon" goal;
Theoretical simulation and characterization technology: Combine density functional theory (DFT) to calculate the electronic structure of active sites, use in-situ XPS and synchrotron radiation technology to observe catalytic reaction intermediates in real time, and achieve "precision catalysis".
Conclusion
From basic research to industrial application, copper oxide catalysts have always shown strong adaptability and innovation. Its unique chemical properties (redox activity, surface site regulation) and physical characteristics (nanomorphology, porous structure) make it a key bridge connecting environmental protection, energy conversion, material synthesis and other fields. With the deep integration of nanotechnology, computational chemistry and green preparation technology, copper oxide catalysts are expected to achieve breakthroughs in more complex reaction systems, providing more efficient solutions for achieving the goal of "carbon neutrality" and the development of sustainable chemistry.

author: Hazel
date:2025-05-28