Electrodeposition of Mo-Rich, MoNi Alloys from an Aqueous Electrolyte

Abstract

The composition limit of electrodeposited molybdenum alloys with nickel is explored from aqueous, citrate electrolytes containing high concentrations of molybdate ions compared to nickel ions. Since molybdate reduction requires the co-deposition of an inducing element, such as nickel, in aqueous media, the ability to fabricate high molybdenum content alloys are a challenge. Here, molybdenumrich, MoNi alloys were successfully, deposited galvanostatically. Electrodeposition experiments were performed on vertically placed, stationary, working electrodes. The deposit composition was characterized by XRF. Deposits having a composition ranging from 62-82 wt%, were realized, requiring high, cathodic, current densities greater than 200 mA/cm 2 , although at extremely low current efficiency, less than 1%. Increasing molybdate concentration in the electrolyte resulted in an increase Mo content in the alloys at a given current density. The partial current densities of Mo, Ni and side reactions are parallel, indicative of a coupled reaction mechanism. The deposit morphology was characterized by SEM. The MoNi alloys had a nodular morphology and contained microcracks. The catalytic property of the MoNi alloys were characterized in a sodium hydroxide electrolyte, and exhibited Tafel behavior consistent with their hallmark feature as a catalysts for electrolytic hydrogen evolution.

Kinetics of Electrochemical Nanonucleation by Induced Codeposition of Iron Group Metals with Refractory Metals (W, Mo, Re)

“…Среди значительного числа различных механизмов (см., например, [1,2,4,[5][6][7][8][9][10][11][12][13][14][15]) можно выделить две группы. Первая [1,[12][13][14][15] основана на образовании смешанного комплекса, содержащего и металл группы железа, и тугоплавкий металл в растворе.…”

“…И электроосаждение сплава происходит из этого комплекса, состав которого определяет соотношение компонентов в сплаве, а, следовательно, свойства. В основе же другой группы методов лежит гипотеза, что прекурсором образования сплава является смешанный поверхностный комплекс, образованный интермедиатами восстановления двух металлов, составляющих сплав [2,[5][6][7][8][9][10][11]. Не вдаваясь в детали предложенных механизмов, можно утверждать, что в Рис.…”

Micropillar Compression Study on the Deformation Behavior of Electrodeposited Ni–Mo Films

“…The conditions of electrodeposition, such as bath composition, pH value, current density and stirring, influence strongly the concentration of the deposited Mo [13][14][15]. It was shown that the Mo content can reach 74 at.% in electrodeposited Ni films, but in this case the current efficiency became extremely low (about 1%) [15,16]. It has also been revealed that appropriate additives may facilitate the deposition of Mo in Ni [17].…”

Design of Highly Active Electrodes for Hydrogen Evolution Reaction Based on Mo-Rich Alloys Electrodeposited from Ammonium Acetate Bath

“…In addition, it has been noted that Mo content in alloys composition can be increased by carrying out the electrodeposition under the pulse current mode [42]. The highest Mo content, 74 at.%, achieved so far by induced electrodeposition in aqueous citrate electrolyte was reported for a Ni-Mo alloy [43].…”