VN Thin Films via MOCVD Using a New Vanadium Precursor: Linking Growth Chemistry to Functional Surface Properties

Vanadium nitride (VN) is a promising material for many applications, including the electrochemical nitrogen reduction reaction (eNRR). Catalyst nanoengineering enables experimental validation of its predicted eNRR activity, but most VN catalysts are made by using methods that lack precise control. This study introduces a new metalorganic chemical vapor deposition (MOCVD) process for high-quality, faceted, and crystalline VN thin films. N,N'-diisopropylformamidinatovanadate [V(dpfamd)₃] is identified as a suitable precursor with favorable thermal properties. Using NH₃ as a co-reactant yields pure crystalline VN thin films on Si substrates. To investigate structure-property relationships relevant to eNRR, the films are characterized by X-ray diffraction (XRD), Rutherford backscattering spectrometry combined with nuclear reaction analysis (RBS/NRA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Observing NH₃'s strong influence during growth, first principles density functional theory (DFT) simulations are performed, supporting an energetically favorable decomposition pathway of [V(dpfamd)₃] to VN with NH₃ present. Process transfer from Si to conductive Ti substrates, required for in-depth electrochemical testing, yields VN thin-film properties similar to those on Si. Preliminary eNRR measurements indicate a potential correlation between faceting and eNRR activity, highlighting the potential of MOCVD-grown VN thin films for future eNRR applications.