Electrodeposition of Cu-Doped MoS2 for Charge Storage in Electrochemical Supercapacitors

doped MoS2 thin films were prepared by one-step electrodeposition from 10.0 mM (NH4)(2)MoS4, 5.0 mM CuSO4, 0.10 M KCl and 0.50 M KSCN at pH 6.95, followed by annealing for three hr. at 500. C in Ar. Cyclic voltammetry in the presence of the SCN- complexing agent yields a cathodic deposition peak that is slightly anodically shifted (similar to 90 mV) relative to the cathodic deposition peaks observed for elecrolytes containing only Cu2+ and only MoS42-. This may provide evidence for the induced co-deposition mechanism, but it is unclear which specific compound is formed. According to RBS and EDX analysis, thin film deposits contain 1-4 atom% Cu and are sulfur-deficient relative to stoichiometric MoS2. Cu dopant incorporation reduces the film resistivity by similar to 10x relative to undoped MoS2. The specific capacitaqnce of Cu-doped MoS2 was also measured by both cyclic voltammetry (CV) and galvanostatic charge-dischrarge (GCD). For 500 nm thick annealed MoS2 films, the specific capacitance of Cu-doped films ranges from 2.5-3.5x higher than that of undoped films during 1000 cycles of CV testing in 1.0MNa(2)SO(4). Capacitance testing also reveals better capacity retention and high scan rate performance for Cu-doped relative to undoped MoS2 films. (C) 2017 The Electrochemical Society. All rights reserved.