Impact of Surface Hydroxyl Groups on CuO Film Growth by Atomic Layer Deposition

CuO-based nanostructures have been widely investigatedin catalysis,sensing, and energy conversion and storage in recent years. The uniqueproperties of these nanostructures are largely related to the morphologyand crystallinity of CuO. The controlled deposition of conformal CuOthin films by atomic layer deposition (ALD) has remained challenginguntil now owing to the limited understanding of the nucleation behaviorand growth process. Here, a novel ALD process for copper oxide wasdeveloped using copper(II) trifluoroacetylacetonate [Cu(tfacac)(2)] as the metal precursor. The nucleation and initial growthof a CuO film are strongly dependent on the surface OH concentration.A continuous particulate-like CuO film was grown on OH-abundant pristineSiO(2) particles, whereas the surface of the annealed SiO2 particles (presenting mostly isolated OH groups) remaineduncoated under the same growth conditions. Moreover, a uniform andconformal CuO film was grown on covalently functionalized CNTs underidentical conditions as pristine SiO2 particles. This studyprovides a strategy for tailoring the structure and the propertiesof thin films via ALD, which is promising for designing well-tailorednanostructures for various applications.

Automated summary

CuO-based nanostructures have been extensively studied in recent years in the fields of catalysis, sensing, and energy conversion and storage. The properties of these nanostructures are closely related to the morphology and crystallinity of CuO. However, the controlled deposition of CuO thin films by atomic layer deposition (ALD) has been challenging due to limited understanding of nucleation behavior and growth process. In this study, a novel ALD process using copper(II) trifluoroacetylacetonate [Cu(tfacac)(2)] as the metal precursor was developed. The nucleation and initial growth of CuO film were found to be dependent on the surface OH concentration. The research provides a strategy for tailoring the structure and properties of thin films via ALD, which has promising applications in designing well-tailored nanostructures.