Electroplated Cu has been extensively applied in advanced electronic packaging, and its mechanical properties are critical for reliability. In this study, Cu foils fabricated through electroplating with various bis-(3-sulfopropyl) disulfide (SPS) concentrations are examined using tensile tests. The SPS concentration affects the grain size of the electroplated Cu foils, resulting in different mechanical properties. A significant Hall-Petch effect, [Formula: see text], is demonstrated for the electroplated Cu foils. The different concentrations of impurities identified through time-of-flight secondary ion mass spectrometry correspond to the different grain sizes, determining the transgranular and intergranular fracture during the tensile test. The results demonstrate that the SPS concentration controlling the microstructures of the electroplated Cu results in a Hall-Petch effect on the mechanical properties of the electroplated Cu foils.
Hydrogen, derived from water splitting, holds promise as a sustainable energy carrier. However, replacing fossil fuels demands large volumes of pure water, a resource that is scarce in numerous regions globally. This study focuses on developing an efficient electrocatalyst for seawater splitting, aiming to conserve freshwater resources and overcome the challenges associated with direct utilization of seawater. Zinc iron layered double hydroxides combined with nickel cobalt sulfides on nickel foam (ZnFe LDH@NiCoS/NF) are produced to operate efficiently in alkaline seawater splitting, which involves the evolution reactions of hydrogen and oxygen. Through the utilization of an alkalinized electrolyte and suitable nickel foam substrates, the adverse effects of corrosion and chlorine oxidation reactions are effectively mitigated. The composite ZnFe LDH@NiCoS/NF exhibits exceptional electrocatalytic efficacy in alkaline seawater, needing remarkably minimal overpotentials of 246.3 mV for the hydrogen evolution reaction (HER) and 284.8 mV for the oxygen evolution reaction (OER) to attain the targeted current density. Additionally, the composite electrocatalyst exhibits decreased Tafel values of 74.6 mV dec–1 for the hydrogen evolution reaction (HER) and 81.5 mV dec–1 for the oxygen evolution reaction (OER), suggesting enhanced kinetics. This improved electrocatalytic performance is attributed to the increased surface area and decreased charge transfer resistance. Additionally, the catalytic electrode exhibits impressive long-term stability, maintaining efficiency for approximately 50 h at a constant current density for both the HER and the OER. This study emphasizes the innovative character of ZnFe LDH@NiCoS/NF as a crucial breakthrough in research on bifunctional electrocatalysts for the HER and the OER, presenting a hopeful direction for harnessing renewable energy from seawater.
The utilization of exceptionally efficient and long-lasting electrocatalysts made from platinum-free materials holds immense promise for mitigating the energy crisis through the production of H2 and O2 via water splitting applications. In this study, a facile hydrothermal method was used to synthesize nitrogen-doped carbon dots (NDCDs) from Luffa acutangula and α-NiS@NDCDs composite from NDCDs, nickel nitrate, and thiourea. The resulting α-NiS@NDCDs composite was characterized using various analytical techniques, such as HR-TEM, EDS, XPS, XRD, and FT-IR. The electrocatalytic hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting reaction (OWS) of NDCDs, α-NiS, and α-NiS@NDCDs composite were evaluated by linear sweep voltammetry, Tafel, chronopotentiometry, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) in 1 M KOH. Remarkably, the α-NiS@NDCDs composite exhibited excellent catalytic activity toward the HER, OER, and OWS, requiring only a low overpotential to achieve a current density of 10 mA cm–2. Furthermore, the greater stability (40 h) of the synthesized α-NiS@NDCDs composite was assessed by chronopotentiometry at a constant current density of 10 mA cm–2. Overall, the synthesized α-NiS@NDCDs composite exhibited promising electrocatalytic activity for the HER, OER, and OWS, highlighting its potential application in energy conversion. The present work confirmed the utility (173 mV, 1.4972 V, and 1.6114 V for the HER, OER, and OWS, respectively) of the α-NiS@NDCDs composite as a promising electrocatalyst for overall water splitting reactions.
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