Electrodeposition from acidic solutions of nickel bis(benzenedithiolate) produces a hydrogen-evolving Ni-S film on glassy carbon

Films electrodeposited onto glassy carbon electrodes from acidic acetonitrile solutions of [Bu₄N][Ni(bdt)₂] (bdt = 1,2-benzenedithiolate) are active toward electrocatalytic hydrogen production at potentials 0.2-0.4 V positive of untreated electrodes. This activity is preserved when the electrode is rinsed and transferred to a fresh acid solution. X-ray photoelectron spectra indicate that the deposited material contains Ni and S, and time-of-flight secondary ion mass spectrometry shows that electrodeposition decomposes the Ni(bdt)₂ assembly. Correlations between voltammetric and spectroscopic results indicate that the deposited material is active, i.e., that catalysis is heterogeneous rather than homogeneous. Control experiments establish that obtaining the observed catalytic response requires both Ni and the 1,2-benzenedithiolate ligand to be present during deposition.