Induced Codeposition Behavior of Electrodeposited NiMoW Alloys

The induced codeposition of Mo and W by Ni was examined together from a citrate-boric acid electrolyte, without the typical ammonia addition, to fabricate ternary NiMoW alloy thin films, determine their partial current densities, and test their ability to catalyze hydrogen. The alloys were galvanostatically electrodeposited onto rotating cylinder electrodes. When molybdate and tungstate have the same concentration in the electrolyte, there is more Mo in the deposit than W. Introducing more molybdate into the electrolyte reduced both Ni and W deposition rates, with negative reaction orders. The metal partial current densities can be attributed to an adsorption model with partially reduced metal species and hydrogen intermediates. A mechanistic model that best predicts the reaction orders of the reducing metal ions, is one where nickel adsorb species catalyze their reduction rate.