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[Display omitted] • HER efficiency depended on electrodeposition time. • Facile and time-effective one-step electrode fabrication. • 50% enhanced hydrogen production compared to untreated electrodes. • 6.5 times higher ECSA of electrodeposited Ni foam. Nickel foam electrodes were treated with a facile and cost-effective electrodeposition method to increase the hydrogen production efficiency in alkaline electrolysis setups. The treated electrodes (Electrodeposited Nickel Foam – ENF) exhibit enhanced electrochemical values compared to a bare nickel foam electrode (NF). A comprehensive analysis is presented on how the electrodeposition time determines the kinetics of hydrogen evolution reaction (HER) and the electrochemical values of the ENF electrodes. It was revealed that deposition time plays a decisive role in the total hydrogen production efficiency. In particular, the ENF electrode with 10 min of electrodeposition, presents a lower Tafel slope, lower overpotentials (|η 10 |=135 mV, |η 100 | = 230 mV), and enhanced hydrogen production (1.5 times higher) compared to an NF electrode. The improved characteristics are mainly attributed to the increased electrochemically active area (6.5 times higher than the NF electrode). Field emission scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were used for the structural and morphological analysis of the electrodeposited nickel foam electrodes. [ABSTRACT FROM AUTHOR]

In the present work, a novel approach has been employed to effectively enlarge the electrocatalytic area of the electrodes in an alkaline electrolysis setup. This approach consists of a two-step electrode fabrication process: In the first step, ultrashort laser pulses have been used to nanostructure the electrode surface. In the second step, electrodeposition of nickel particles was performed in a modified Watt's bath. The resulting electrodes have been found to exhibit a significantly increased hydrogen evolution reaction (HER) activity. Compared to the laser-nanostructured electrode (LN) and an untreated (i.e., flat) electrode, the electrodeposited-laser-nanostructured (ELN) electrode provides (i) enhanced electrochemical values (ii) a significant increase of double-layer capacitance (C DL) (values up to 1945 μF cm−2) compared to that of an LN electrode (288 μF cm−2) (iii) higher J peaks at CVs sweeps and (iv) lower Tafel slopes (−121 mV dec−1 compared to −157 mv dec−1). The ELN electrode provides an overpotential value of |η| 100 = 264 mV, which shows a noteworthy 34% decrease compared to a flat Ni electrode and a 15% decrease to an (LN) electrode. Scanning electron microscopy (SEM) revealed that the electrodeposition of nickel on the LN nickel electrodes results in a dendrite-like morphology of the surface. Thus, the enhancement of the HER has been attributed to the dendrite-like geometry and the concomitant enlargement of the electrocatalytic area of the electrode, which presents an electrochemical active surface area (ECSA) = 97 cm−2 compared to 2.8 cm−2 of the flat electrode. The electrodes have also been tested in actual hydrogen production condition, and it was found that the ELN electrode produces 4.5 times more hydrogen gas than a flat Ni electrode and 20% more hydrogen gas than an LN electrode (i.e. without the extra nickel electrodeposition). [Display omitted] • Two-step Ni electrode fabrication process; laser nanostructuring and electrodeposition of Ni particles. • Enhanced hydrogen production up to 4.5 times in alkaline electrolysis using Electrodeposited-Laser-Nanostructured Ni substrates. • Electrochemical evaluation for HER, providing improved values of Tafel slope (b = −121.3 mV dec−1), overpotential values of η 10 = 108 mV and η 100 = 264 mV and ECSA = 97 cm−2. [ABSTRACT FROM AUTHOR]

This study describes the fabrication of ultrafast laser-induced periodic nanostructures on Nickel sheets and their use as cathodes in alkaline electrolysis. For the first time, to the best of our knowledge, laser-nanostructured Ni sheets were used as cathode electrodes in a custom-made electrolysis cell at actual, Hydrogen producing conditions, and their efficiency has been compared to the untreated Nickel sheets. The electrochemical evaluation showed higher J peaks , lower overpotential, and enhanced double-layer capacitance for the nanostructured electrode. A decrease in the Tafel slope was also found for the nanostructured electrode. The hydrogen production efficiency was found to be 3.7 times larger for the laser-nanostructured Nickel electrode, which was also confirmed by current-time measurements during electrolysis. Also, a novel approach is proposed to improve the stability of the current density during electrolysis and, therefore, the hydrogen production process by about 10%. [Display omitted] • Laser nanostructured Ni electrodes produce higher values of hydrogen gas. • An Electrochemical evaluation of laser nanostructured Ni electrodes. • A Correlation between electrical measurements and hydrogen production during electrolysis. [ABSTRACT FROM AUTHOR]