Electrodeposition of Iron-Group Alloys into Nanostructured Oxide Membranes: Synthetic Challenges and Properties

Abstract

Background: Quasi-one dimensional nanostructures: nanowires, nanotubes, nanorods, nanobelts/nanoribbons and complex "nanowire-nanoparticle" composites have been synthesized over the years. These nanostructures are particularly appealing due to their specific properties defined by their high aspect ratio: two dimensions are in the nanoscale range and one dimension is in the microscale. Methods:One of the well-designed approaches for the synthesis of such nanostructured materials is template-assisted fabrication combined with electrodeposition. The fabrication approaches for the growth of iron-group alloy nanostructures inside nanoporous oxide membranes by means of different electrodeposition techniques, and the resulting unique properties and potential applications of this type of materials are reviewed. Results:Arrays of nanostructures can be obtained by filling a porous oxide template that contains a large number of straight cylindrical, nano-sized diameter holes. Generalities of metals electrodeposition into nanoporous oxide membranes are discussed. Measures to minimize the nonuniformity of deposits inside pores need to be addressed to thin the barrier layer, to control hydrogen evolution and to improve mass transport inside the pores. Examples of binary and ternary iron group alloys grown inside nanoporous oxide templates are provided. Catalytic hydrogen evolution and methanol oxidation on the nanowires arrays are described. The "sample size effect" on the magnetic properties of materials and the electrodeposition of multilayered structures necessary for giant magnetoresistance (GMR) are discussed in details. Conclusion:Electrodeposition of binary and ternary iron-group alloys confirm that controlling alloy composition inside nanopores is still a challenge. composites [7] have been synthesized over the years. These nanostructures are particularly appealing due to their specific properties defined by their high aspect ratio: two dimensions are in the nanoscale range and one dimension is in the microscale. One of the well-designed approaches for the synthesis of such nanostructured materials is template-assisted fabrication combined with electrodeposition, first reported by Possin [8] in track etched mica films, and expanded upon by others with different materials and templates [2,[9][10][11][12][13][14]. However, the self-organized porous anodic aluminum oxide (AAO) membrane has become one of the most often used templates for tunable synthesis of different nanostructured materials [15,16].

Features of the Electrochemical Deposition of Films from a Triple System of CoNiFe

“…Electrochemical deposition was carried out at the temperature of 70°С from chloride electrolyte with component ratio CNi/CFe/CCo = 1/1/1. A review of the literature [1]- [5], [18]- [50] shows that none of the researchers used this method of research.…”

Normal Electrochemical Deposition NiFe

“…Summing up the results of the analysis of chemical characteristics of hydrolysis of ferric chloride, it should be noted that researchers in over 65 years [2] conducted NiFe alloy plating and receive preferential deposition of iron in relation to nickel in all formulations electrolyte. Electrolytes used [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] is characterized by a wide range of molar relationship of nickel and iron. The cause of the anomalous codeposition of preferential deposition of iron sources previously not associated with the main feature of iron ionsthe existence of variable Valence iron one and two values in the charge of ions during the hydrolysis of iron salts.…”

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

“…Важно также подчеркнуть, что основной причиной нелинейности, и в частности экспоненциальной зависимости плотности от координаты (уравнение (6)), должна быть высокая скорость распространения фронта кристал- Таблица. Влияние плотности тока на размер кристаллитов и содержание абсорбированного водорода при электроосаждении Fe-W покрытий из цитратного раствора [26] Плотность тока, мA/cм 2 Тип осадка Размер cубзерен, нм Содержание водорода, cм 3 На примерах свойств покрытий сплавами Fe-W и Сo-W, получаемых из различных электролитов, можно показать, что свойства их определяются в конечном счете высокой скоростью распространения фронта кристаллизации. Так, например, в соответствии с результатами работы [26] переход от кристаллических покрытий к нанокристаллическим сплавам Fe-W (Fe-W-H) из цитратного электролита имеет место при увеличении плотности тока электроосаждения (при фиксированной ОПТ) (рис.…”

“…Электроосаждение сплавов металлов группы железа (Fe, Со, Ni) c тугоплавкими металлами (W, Mo, Re) представляет значительный интерес в плане применения как получаемых объемных материалов и структур в качестве упрочняющих, антикоррозионных, магнитных, каталитически активных покрытий и слоев, так и квазиодномерных структур (нанопроволок, нанотрубок, нанолент и т.д.) [1][2][3]. Управление составом и свойствами таких материалов и структур вызывает значительный интерес исследователей еще и по той причине, что с точки зрения классических методов управления составом сплавов, получаемых электрохимически, эти процессы относятся к категории аномальных [1].…”