Search

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]