Papers by Keyword: Hydrogen Evolution Reaction

Abstract: Over the course of history, the principles of alloying have evolved, with the past fifteen years witnessing the rise of high-entropy alloying theory, which has fundamentally transformed our approach to alloy design. Developing cost-effective and efficient electrocatalysts is critical for large-scale hydrogen production via water splitting. The Ni-Co-W-Zr-P alloy coating offers a promising alternative to noble metal-based electrocatalysts. In this study, we developed a Co-W-Zr-incorporated Ni(P) coating using the electroless plating method. The integration of Co-W-Zr into the Ni(P) matrix notably enhances the number of active sites during the hydrogen evolution reaction. Electrochemical studies revealed a low overpotential of 413.5 mV of the coating when the current density is at −10 mA cm⁻². Kinetic parameters were analyzed using EIS measurements, and a potential mechanism for the hydrogen evolution reaction (HER) was proposed. The coating demonstrated exceptional stability, with no surface degradation even after prolonged electrochemical testing, making it suitable for large or irregularly shaped electrodes required in industrial applications.

Abstract: Hydrogen evolution reactions (HER) are important in a variety of electrochemical devices, such as electrolysers and fuel cells. To reduce the reaction overpotential and reduce energy consumption, efficient, low-cost, and durable electrocatalysts must be developed. Needle-less electrospinning (NLE) technique was used to prepare the fibrous electrocatalyst. NLE is a user-friendly and adaptable technique for large-scale low-cost fiber production. NLE created transition metal phosphides carbon fibers (TMP CF). The precursor foam was folded between two Al₂O₃ ceramic plates. The heat treatment was carried out in a tube furnace at 1200 °C in an Ar atmosphere, followed by a reduction in an H₂ atmosphere at 780 °C. The electrolyser's membrane electrode assembly can be immediately submerged in the final TMP CF in the form of plates. The created NiCoP catalytic plates could be directly used in electrolyser's membrane electrode assembly of PEM electrolysers. In a three-electrode system, the electrochemical activity of the produced electrocatalysts was evaluated using linear sweep voltammetry. The electrochemical activity of the produced electrocatalysts were evaluated using linear sweep voltammetry. The catalyst's stability and endurance in acidic and alkaline environments were investigated.

Abstract: Hydrolysis for hydrogen production is one of the most efficient ways to produce hydrogen energy. In order to realize its wide application, people urgently need to find cheap and efficient metal-free electrocatalysts to replace the noble-metal electrocatalysts in hydrogen evolution reaction (HER). Here, N-doped hierarchical porous carbon materials were successfully fabricated without any template. We changed the nitrogen and carbon source needed to prepare the material and tested HER performance. In all samples, the ethylenediamine-based porous carbon material (NPC-2) compared with other nonmetallic heteroatom doped carbon materials and some traditional metallic catalysts exhibited outstanding HER performance and stability in acid solution. To achieve a 10 mA/cm² HER current density, the nitrogen-doped hierarchical porous carbon materials (NPC-2) required an overpotential of 398 mV.

Abstract: The present study reports the enhanced electrocatalytic activity of Ni-Co alloy coatings due to addition of known quantity of carbon nanotube (CNT) into the bath. The Ni-Co-CNT composite coatings were electrodeposited on copper substrate from a sulphate bath, using glycerol as the additive. Electrocatalytic efficiency of the coatings, used as electrodes were tested for both Hydrogen evolution reaction (HER) and Oxygen evolution reaction (OER) in 1M KOH using cyclic voltametry and chronopotentiometric techniques. The experimental conditions were optimized to maximize the electrocatalytic activity of both Ni-Co and Ni-Co-CNT coatings for HER and OER. The experimental results revealed that Ni-Co-CNT coatings deposited at high current densities are more favorable for OER and HER, compared to bare Ni-Co coatings deposited from same bath, under same condition. The substantial improvement in the electrocatalytic activity of Ni-Co-CNT composite coatings was attributed to increased porosity due to addition of CNT. The structure-property relationship of both Ni-Co and Ni-Co-CNT alloy coatings for HER and OER were used to explain the role of CNT in enhancing electrocatalytic activity, with the support of XRD, SEM and EDX analyses.

Abstract: In the present work, efficient electrode material for water splitting reaction has been developed through electrodeposition method. The nanocrystalline Ni-Mo alloy coatings were deposited at different cathode current densities (c.d.) on copper substrate. The electrocatalytic activity of the electrodeposits for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH were evaluated by electrochemical techniques like cyclic voltammetry (CV) and chronopotentiometry (CP). The corrosion stability of the Ni-Mo alloys was tested in same alkaline medium by potentiodynamic polarization study. The experiment results demonstrated thatNi-Mo alloy deposited, respectively at 1.0 A dm^-2 (38.3 wt.% Mo) and 4.0 A dm^-2 (33.2 wt.% Mo) are good electrode materials for HER and OER. Further, Ni-Mo alloy deposited at 4.0 A dm^-2 was found to be most corrosion resistant in the alkaline medium. The electrocatalytic activity of Ni-Mo alloys were explained in terms of their surface morphology, phase structure and chemical composition, confirmed by XRD, SEM and EDX analysis.

Abstract: For more energy-efficient and economical hydrogen production, highly active noble metal-free hydrogen evolution catalysts are a priority for all. Herein, we report a facile one-pot hydrothermal synthesis of CoSe₂ nanoparticles with their electrocatalytic performance for hydrogen evolution reaction. The synthesized CoSe₂ nanoparticles have an average diameter of 50-70 nm with a uniform distribution. They also exhibited good electrocatalytic performance for hydrogen evolution reaction with the onset overpotential and Tafel slope of 140 mV and 95 mV/dec, respectively. The results provide a facile and effective way for the exploration of efficient Co-based HER catalysts.

Abstract: The production high purity hydrogen by water electrolysis based renewable sources as a mean to store energy, has gained some attention in the last years due to the high specific energy of hydrogen, the potentially neutral carbon and zero emission of the usage of H₂ as fuel. However, it remains certainly necessary to develop efficient and lower cost electrolyzers. Such a situation requires the search for and the development of inexpensive and stable electrode materials, showing low polarization to hydrogen evolution reduction (HER). In this work copper and nickel oxides were studied for use as electrodes for the reduction of hydrogen in alkaline water electrolysis. The nickel and copper oxide composites coatings were deposited electrochemically as oxides/hydroxides on a stainless steel (SS) electrode and characterized using electrochemical methods such as cyclic voltammetry (CV), cathodic polarization and Tafel slops. The HER was studied using as electrolytic cathodes unmodified AISI 304 stainless steel (SS), nickel coated stainless steel (SS/Ni), copper coated stainless steel (SS/Cu), and nickel (under layer) and copper (top layer) coated stainless steel (SS/Ni/Cu) in 5 M KOH solution. It was found that, the SS/Ni/Cu electrode presents good electrocatalytic activity and stability toward the HER, compared to the SS electrodes modified by single nickel oxide layer. This behavior seems be explained by the synergistic interaction of Ni and Cu with Fe present in the stainless steel.

Abstract: Knowledge of the mechanism and the kinetics of hydrogen evolution reaction (HER) is essential for tailoring new electrode materials with electrocatalytic activity towards HER. This review paper deals with some problems related to determination of the kinetics of multi-step reaction of HER, especially on porous electrodes. Theoretical background of HER has been briefly presented. The importance of electrochemical impedance spectroscopy (EIS) method for studies of the detailed mechanism and kinetics of HER and some problems in understanding of the interpretation ac impedance results, have been discussed.

Abstract: The Ni+W composite coatings were prepared by electrodeposition under the galvanostatic conditions (j_dep = -300 mA cm^-2) from the nickel plating bath containing an addition of tungsten powder of different granulation (<150 nm, 12 μm, <150 μm). For comparison, the Ni-W alloy coating was also obtained. Studies of hydrogen evolution reaction (HER) were carried out in 5 M KOH solution at room temperature using steady-state polarization and electrochemical impedance spectroscopy (EIS) measurements. It was found that for the Ni+W (<150 μm) composite coating increase in the activity of HER was observed in comparison with the others coatings.

Abstract: The Ni+Mo composite coatings were prepared by electrodeposition under the galvanostatic conditions (j_dep = -300 mA cm^-2) from the nickel plating bath containing a suspension of molybdenum powder with different granulation (<100 nm, 3-7 μm, <150 μm). Kinetics of hydrogen evolution reaction (HER) was studied in 5 M KOH solution at room temperature using steady-state polarization and electrochemical impedance spectroscopy (EIS) measurements. It was found that the rate of the HER is dependent on the granulation of Mo powder used as composite component. The highest kinetics of the HER was revealed for the Ni+Mo (3-7 μm) composite electrode, and the increase in its electrochemical activity was attributed to the increase in the real surface area development and the intrinsic activity.