Size-dependent effects of Cu° nanoparticles on electronic properties and ethanol dehydrogenation catalysis via Cu⁺-O-Cu⁺ species

• Published in: Materials today chemistry 2024-10, Vol.41, p.102318, Article 102318
• Main Authors: Osmari, Taynara A., Petrolini, Davi D., Lopez-Castillo, Alejandro, Henrique de Morais, Leonardo, Zanchet, Daniela, Sainna, Mala A., Willock, David, Gallo, Jean Marcel R., dos Santos, João B.O., Bueno, José Maria C.
• Format: Article
• Language: English
• Subjects: Cu-CuO sites on Cu nanoparticles; Cu/SiO2 catalysts; Ethanol dehydrogenation; In situ characterization
• ISSN: 2468-5194; 2468-5194
• DOI: 10.1016/j.mtchem.2024.102318

Copper (Cu) nanoparticles, widely utilized as catalysts in industrial applications, exhibit intriguing behavior in structure-sensitive reactions like ethanol dehydrogenation. Contrary to expectations, the catalytic activity does not consistently increase as the size of Cu nanoparticles decreases. In Cu catalysts, the particle size significantly effects the Cu0/Cu+ ratio on the nanoparticle surface. Decreasing the size of Cu nanoparticles promotes their oxidation, leading to the formation of Cu+ and O2− species. This alteration subsequently influences the structural and electronic properties of the catalytic Cu sites. Through Cu nanoparticle calculations, the presence of an O ad-atom was identified to modify the electron density at the Cu site, thereby altering the ethanol adsorption energy and impacting the overall catalytic activity. The increase in O coverage, due to size effects, resulted in a notable decrease in the heat of adsorption on Cu nanoparticles (by approximately 20 kJ mol− 1). The observed high ΔEads indicates that more ethanol molecules could reach the transition state for the reaction, subsequently augmenting turnover rates (TOF) and reducing the apparent activation energy (Eaap) concerning Cu particle size. [Display omitted] •Altered electron density at the Cu sites changes ethanol adsorption and catalysis.•Reduction in particle size enhances Cu0 to Cu + oxidation.•This oxidation affects the structural and electronic properties of the nanoparticles.•Reduced particle size lowers adsorption heat by 20 kJ mol−1, boosting catalytic efficiency.