Atomic description of the atomic layer deposition of diethylzinc and water on carboxyl functionalized carbon nanotubes: a first principle study.*

In this work, we describe -at the atomic level- the full reaction mechanism involved in the formation of a hybrid inorganic ZnO/CNT structure. The chemically inert CNTs are activated with a carboxylic acid. Diethylzinc (DEZ) and water are used as gas-phase precursors to form ZnO. Our findings show that DEZ is physically adsorbed on the CNT; after a ligand-exchange mechanism involving overcome an energy barrier of 0.06 eV, ethyl zinc and ethane are formed. The energy barrier is minimal compared with previous values of 0.6 eV for OH functionalized surfaces and is associated with the CO group that mediates DEZ's proximity.
Moreover, upon exposure to the oxidizing agent (H20), the last ligand-exchange reaction is achieved with an energy barrier of 0.88 eV to form ethane and ZnO and complete the self-limiting reaction. We have analyzed the role of the second precursor's saturation and identified a collective mechanism formed between water molecules and carboxylic acid to lower the energy barrier on the second ALD step. Non-covalent interactions are used to visualize the driving forces during each partial reaction in real space.