Electroless deposition of Ni-W-Mo-Co-P films as a binder-free, efficient and durable electrode for electrochemical hydrogen evolution

Abstract

In this study, the manufacture of Ni-W-Mo-Co-P, Ni-Mo-Co-P, Ni-W-Co-P, Ni-W-Mo -P, Ni-Co-P, Ni-Mo-P, Ni-W-P, and Ni-P alloying coatings through electroless method on the copper substrate was investigated. The elemental and structural tests showed that the alteration of the Ni-P electroless basic bath composition by introducing sodium tungstate, sodium molybdate, and cobalt chloride additives enabled the deposition of alloying coatings. Linear Sweep Voltametry (LSV) tests revealed that the Ni-W-Mo-Co-P sample (NWMCP) coated in an alkaline bath with 18 g/l Nickel (II) sulfate, 12 g/l Ammonium acetate, 12 g/l Sodium citrate, 12 ml Lactic acid, 12 g/l Sodium hypophosphite, 8 g/l Sodium tungstate, 0.2 g/l Sodium molybdate, and 10 g/l Cobalt (II) chloride was featured with the best electrocatalytic properties with η10 = −41, η20 = −46, η100 = −67 mV and tafel slope of 38 mV.dec−1. Scanning Electron Microscope (SEM) observations and Cyclic Voltametry (CV) electrochemical tests showed that morphology had a negligible effect on electrocatalytic performance of the coating. In addition, the presence of alloying elements improved the coating intrinsic properties by changing its electronic structure. Electrocatalytic stability was assessed using chronoamperometry, cyclic voltammetry, and stepwise chronoamperometry tests, introducing NWMCP sample a durable electrode generation with good stability.