Hydrogen Evolution Reaction on Atomic Layer Deposited Molybdenum Nitride (MoNx) Thin Film on Highly Porous Carbon Cloth-Based Substrate

Abstract

Using the atomic layer deposition (ALD) technique, a uniform, and conformal thin film of molybdenum nitride (MoNx) is successfully coated on to a highly porous carbon cloth-based substrate. The precursor used in ALD-MoNx is molybdenum hexacarbonyl (Mo(Co)6), and ammonia is used as the nitrogen source, while the temperature and number of ALD cycles are set at 225︒C and 700 cycles, respectively. The phase, surface characteristic, thickness, and conformal deposition of the film is established using XRD, XPS and SEM imaging, respectively. A conformal and uniform film with a thickness of 25–30 nm, and with overall composition c.a. Mo0.59N0.41 is observed. The as-deposited film exhibits predominantly amorphous characteristic, with a minor nanocrystalline nature. The film has noticeable oxygen contamination, mainly at the surface. Hydrogen evolution reaction (HER) performance of the as-prepared electrode is evaluated in 0.5 M H2SO4 electrolyte in a conventional three-electrode setup using the Ag/AgCl (3 M KCl) and graphite rod, as reference and counter electrode, respectively. The electrode exhibits good HER performance attributed to the high surface area of the substrate. Further, the porous structure of the electrode is systematically investigated using SEM imaging, and electrochemical impedance spectroscopy (EIS). A direct correlation of pore geometry is established by studying the HER at different overpotential, electrode composition, and nature of the electrolyte. Acknowledgement This work was financially supported by the MOTIE (Ministry of Trade, Industry & Energy (#10080651) and KSRC (Korea Semiconductor Research Consortium) support program for the development of the future semiconductor device and the Advanced Technology Center Program (#10077265) funded by the MOTIE (Ministry of Trade, Industry & Energy) of the Republic of Korea