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1. Spatially Directed Functionalization by Co-electropolymerization of Two 3,4-ethylenedioxythiophene Derivatives on Microelectrodes within an Array

   https://doi.org/10.1149/1945-7111/abcb75  

   Jones, Benjamin J.; Korzeniewski, Carol; Franco, Jefferson H.; Minteer, Shelley D.; Fritsch, Ingrid (December 2020, Journal of The Electrochemical Society)

   Electrodeposited conductive copolymer films with predictable relative properties (quantities of functional groups for further modification and capacitance) are of interest in sensors, organic electronic materials and energy applications. Potentiodynamic copolymerization of films in aqueous solutions of two different thiophene derivatives, (2,3-dihydrothieno[3,4-b]dioxin-2-yl)methanol (1) and 4-((2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)-methoxy)-4-oxobutanoic acid (2), containing 0.02 M total monomer (0, 25, 34, 50, 66, 75, 100 mol%2), 0.05 M sodium dodecyl sulfate, and 0.1 M LiClO₄, on gold microelectrodes in an array was investigated. Decreasing monomer deposited (m)from 0 to 100 mol%2is attributed to a decreasing pH that inhibits electropolymerization. Molar ratios of1and2in the films, determined by micro-attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, tracks closely with the ratio in the deposition solutions. Capacitances measured from cyclic voltammetry in aqueous buffer and electron transfer of ferrocyanide at the films are unaffected by copolymer composition, except for the 100 mol%2case. Ratios of reverse-to-forward faradaic peak currents suggest that films with high content of1expand in the anodic form and contract in the cathodic form and vice versa for films with high content of2, where anions and cations dominate counterion transport from solution, respectively. 

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2. Electrodeposited thin-film Cu _x Sb anodes for Li-ion batteries: enhancement of cycle life via tuning of film composition and engineering of the film-substrate interface

   https://doi.org/10.1039/c8ta01798k  

   Schulze, Maxwell C.; Schulze, Roland K.; Prieto, Amy L. (January 2018, Journal of Materials Chemistry A)

   Electrodeposited Cu–Sb thin films on Cu and Ni substrates are investigated as alloy anodes for Li-ion batteries to elucidate the effects of both the film composition and substrate interactions on anode cycling stability and lifetime. Thin films of composition Cu x Sb (0 < x < 2) exhibit the longest cycle lifetimes nearest x = 1. Additionally, the Cu–Sb films exhibit shorter cycle lifetimes when electrodeposited onto Cu substrates when compared to equivalent films on Ni substrates. Ex situ characterization and differential capacity analysis of the anodes reveal that significant interdiffusion occurs during cycling between pure Sb films and Cu substrates. The great extent of interdiffusion results in mechanical weakening of the film–substrate interface that exacerbates film delamination and decreases cycle lifetimes of Cu–Sb films on Cu substrates regardless of the film's composition. The results presented here demonstrate that the composition of the anode alone is not the most important predictor of long term cycle stability; the composition coupled with the identity of the substrate is key. These interactions are critical to understand in the design of high capacity, large volume change materials fabricated without the need for additional binders. 

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3. Electrodeposition of Molybdenum from Water-in-Acetate Electrolytes

   https://doi.org/10.1149/1945-7111/ad59c8  

   Liu, Quanhong; Huang, Qiang (June 2024, Journal of The Electrochemical Society)

   This paper reports a systematic study on the electrodeposition of metallic molybdenum from water-in-salt electrolytes containing superhigh concentrations of acetate. Cyclic voltammetry and DC deposition were carried out on rotating disk electrodes with various concentrations of CH₃COOK and CH₃COONH₄to determine the effects of NH₄⁺and K⁺on Mo deposition. A comparison was performed between CH₃COOLi, CH₃COONa, and CH₃COOK to study the effects of different alkali metal cations. A synergistic effect was observed between K⁺and NH₄⁺, where Mo deposition rate is enhanced in the presence of both cations. However, such synergistic effect was not observed between NH₄⁺and other alkali cations. In addition, the impact of substrate on Mo deposition was also studied using Pt and Cu electrodes with different activity toward hydrogen evolution reaction. Electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were used to characterize the surface morphology, crystallographic structure, and metallic state of Mo in the electrodeposited films. 

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4. Combinatorial Growth of Vertically Aligned Nanocomposite Thin Films for Accelerated Exploration in Composition Variation

   https://doi.org/10.1002/smsc.202300049  

   Rutherford, Bethany X.; Zhang, Di; Quigley, Lizabeth; Barnard, James P.; Yang, Bo; Lu, Juanjuan; Kunwar, Sundar; Dou, Hongyi; Shen, Jianan; Chen, Aiping; et al (September 2023, Small Science)

   Combinatorial growth is capable of creating a compositional gradient for thin film materials and thus has been adopted to explore composition variation mostly for metallic alloy thin films and some dopant concentrations for ceramic thin films. This study uses a combinatorial pulsed laser deposition method to successfully fabricate two‐phase oxide–oxide vertically aligned nanocomposite (VAN) thin films of La_0.7Sr_0.3MnO₃(LSMO)‐NiO with variable composition across the film area. The LSMO‐NiO compositional gradient across the film alters the two‐phase morphology of the VAN through varying nanopillar size and density. Additionally, the magnetic anisotropy and magnetoresistance properties of the nanocomposite thin films increase with increasing NiO composition. This demonstration of a combinatorial method for VAN growth can increase the efficiency of nanocomposite thin film research by allowing all possible compositions of thin film materials to be explored in a single deposition. 

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5. Dealloying Behavior of NiCo and NiCoCu Thin Films

   https://doi.org/10.1155/2016/2935035  

   Peecher, Benjamin E.; Hampton, Jennifer R. (January 2016, International Journal of Electrochemistry)

   Porous metals and alloys, such as those fabricated via electrochemical dealloying, are of interest for a variety of energy applications, ranging from their potential for enhanced catalytic behavior to their use as high surface area supports for pseudocapacitor materials. Here, the electrochemical dealloying process was explored for electrodeposited binary NiCo and ternary NiCoCu thin films. For each of the four different metal ratios, films were dealloyed using linear sweep voltammetry to various potentials in order to gain insight into the evolution of the film over the course of the linear sweep. Electrochemical capacitance, scanning electron microscopy, and energy dispersive X-ray spectroscopy were used to examine the structure and composition of each sample before and after linear sweep voltammetry was performed. For NiCo films, dealloying resulted in almost no change in composition but did result in an increased capacitance, with greater increases occurring at higher linear sweep potentials, indicating the removal of material from the films. Dealloying also resulted in the appearance of large pores on the surface of the high nickel percentage NiCo films, while low nickel percentage NiCo films had little observable change in morphology. For NiCoCu films, Cu was almost completely removed at linear sweep potentials greater than 0.5 V versus Ag/AgCl. The linear sweep removed large Cu-rich dendrites from the films, while also causing increases in measured capacitance. 

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