Study Of Hydrogen Evolution Reaction Research Articles

Effect of Stacking Interactions on the Translation of Structurally Related Bis(thiosemicarbazonato)nickel(II) HER Catalysts to Modified Electrode Surfaces.

A series of crystalline nickel(II) complexes (1-3) based on inexpensive bis(thiosemicarbazone) ligands diacetylbis(4-methyl-3-thiosemicarbazone) (H2ATSM), diacetylbis(4,4-dimethyl-3-thiosemicarbazone) (H2ATSDM), and diacetylbis[4-(2,2,2-trifluoroethyl)-3-thiosemicarbazone] (H2ATSM-F6) were synthesized and characterized by single-crystal X-ray diffraction and NMR, UV-visible, and Fourier transform infrared spectroscopies. Modified electrodes GC-1-GC-3 were prepared with films of 1-3 deposited on glassy carbon and evaluated as potential hydrogen evolution reaction (HER) catalysts. HER studies in 0.5 M aqueous H2SO4 (10 mA cm-2) revealed dramatic shifts in the overpotential from 0.740 to 0.450 V after extended cycling for 1 and 2. The charge-transfer resistances for GC-1-GC-3 were determined to be 270, 160, and 630 Ω, respectively. Characterization of the modified surfaces for GC-1 and GC-2 by scanning electron microscopy and Raman spectroscopy revealed similar crystalline coatings before HER that changed to surface-modified crystallites after conditioning. The surface of GC-3 had an initial glasslike appearance before HER that delaminated after HER. The differences in the surface morphology and the effect of conditioning are correlated with crystal-packing effects. Complexes 1 and 2 pack as columns of interacting complexes in the crystallographic a direction with short interplanar spacings between 3.37 and 3.54 Å. Complex 3 packs as columns of isolated molecules in the crystallographic b direction with long-range interplanar spacings of 9.40 Å.

Recent Progresses in Electrocatalysts for Water Electrolysis

The study of hydrogen evolution reaction and oxygen evolution reaction electrocatalysts for water electrolysis is a developing field in which noble metal-based materials are commonly used. However, the associated high cost and low abundance of noble metals limit their practical application. Non-noble metal catalysts, aside from being inexpensive, highly abundant and environmental friendly, can possess high electrical conductivity, good structural tunability and comparable electrocatalytic performances to state-of-the-art noble metals, particularly in alkaline media, making them desirable candidates to reduce or replace noble metals as promising electrocatalysts for water electrolysis. This article will review and provide an overview of the fundamental knowledge related to water electrolysis with a focus on the development and progress of non-noble metal-based electrocatalysts in alkaline, polymer exchange membrane and solid oxide electrolysis. A critical analysis of the various catalysts currently available is also provided with discussions on current challenges and future perspectives. In addition, to facilitate future research and development, several possible research directions to overcome these challenges are provided in this article.Graphical

Efficient hydrogen evolution catalysis triggered by electrochemically anchored platinum nano-islands on functionalized-MWCNT

We report the electrochemical deposition (ECD) of platinum nano-islands (Pt NIs) on functionalized multi-walled carbon nanotubes (ECD Pt NIs@f-MWCNT) as an efficient electrocatalyst for the hydrogen evolution reaction (HER). Pristine MWCNT was acid treated to induce the number of oxygen functional groups on the surface and enhances the wettability. Thereafter, Pt nanoparticles (Pt Nps) were deposited by a simple electrodeposition technique on the oxygen enriched MWCNT surface. The Pt NIs@f-MWCNT has been physicochemically characterized using X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and X-ray photoelectron Spectroscopy (XPS). The TEM analysis showed the presence of Pt NIs on MWCNT wherein, the NIs were made up of small Pt nanoclusters of ∼4 nm in dimension. The electrochemical HER studies were carried out using linear sweep voltammetry (LSV), Tafel polarization and electrochemical impedance spectroscopy (EIS). An overpotential (ɳ) of −84 mV was obtained at a current density (j) of −10 mA/cm2. The amount of Pt loading has been optimized through electrodeposition. Enhanced HER activity was observed with a Pt loading of 3.8 μg/cm2. In order to ascertain the durability of the catalyst, accelerated degradation test (ADT) was carried out for 10,000 cycles at a scan rate (ʋ) of 100 mV/s. The turnover frequency (TOF) was estimated to be 6.3 s−1 at ɳ = −70 mV.

Stacking sequence dependent photo-electrocatalytic performance of CVD grown MoS2/graphene van der Waals solids

New layered solids by the combinatorial stacking of different atomic layers are emanating as novel candidates for energy efficient devices. Here, sequentially stacked single layer graphene-molybdenum disulfide (MoS2) van der Waals (vdW) solids are demonstrated for their efficacy in the catalysis of hydrogen evolution reaction (HER), and importance of their stacking order in tuning the photo-electrocatalytic (PEC) efficiency is unraveled. Single layer graphene and a few layered MoS2 stacked vdW solids based transparent flexible electrodes were prepared, and a particular stacking sequence where top-graphene: bottom-MoS2/polydimethylsiloxane (PDMS) geometry (MSGR) exhibited the lowest onset and over potentials and a very high exchange current density (j0 ∼ 245 ± 1 μA cm−2) in acidic HER in comparison to the individual layers and other stacked configuration (MoS2 on top of graphene on PDMS, GRMS). The HER studies under dark and white light illuminations were conducted to explore the PEC responses of the devices. The augmented HER performance of MSGR is further confirmed from the charge transfer resistance measurements using electrochemical impedance spectroscopy. Role of graphene plasmonics and MoS2 to graphene electron transfer were studied, and this study unravels the importance of a new factor, stacking order of vdW layers, while designing novel devices from the layered solids.

A comparative study of hydrogen evolution reaction on pseudo-monolayer WS2 and PtS2: insights based on the density functional theory

In this study, we investigated the catalytic activity of ultrathin PtS2 and WS2 nanostructures for the hydrogen evolution reaction by electronic structure calculations based on the spin-polarised density functional theory.

몰리브덴 산화물이 도핑된 티타늄 나노튜브전극의 수소 발생 반응 연구

몰리브덴 산화물이 도핑된 티타늄 나노튜브전극의 수소 발생 반응 연구

A novel Pt@Te-reduced graphene oxide/polyimide composite catalyst for hydrogen evolution

A promising Pt@Te nanoparticles catalyst has been synthesized on the surface of the reduced graphene oxide/polyimide (rGO/PI) substrate. First of all, Te was deposited on the rGO/PI using electrochemical deposition method to obtain Te-rGO/PI that has various morphologies. Secondly, a monolayer Pb film was deposited on the Te-rGO/PI by the similar electrochemical method to get a transition state material of Pb@Te-rGO/PI. Finally, the target Pt@Te catalyst on the rGO/PI with large surface area was obtained by a chemical oxidation method, in which Pb was stripped off from the Pb@Te-rGO/PI by an oxygenation of H2PtCl6, while the oxygenation process, Pt replaced Pb to be deposited on the surface of Te-rGO/PI to form Pt@Te-rGO/PI. Then the prepared Pt@Te-rGO/PI was used as a working electrode to study the hydrogen evolution behavior in 0.5 mol/l H2SO4. By comparison the catalyst of sole Pt-rGO/PI nanoparticles, Pt@Te-rGO/PI catalyst considerably abated the demanding of Pt. And it shows excellent HER activities with a low overpotential of 0.1 V. The Tafel slope of 55 mV dec−1 reveals most likely the Volmer–Heyrovsky mechanism for hydrogen evolution reaction (HER). On the other hand, the catalyst displays satisfactory stability. This work may pave a potential pathway for synthesizing multi-morphology nano-Pt catalyst with high surface area for application in the study of HER.

The Influence of Temperature of Electrodeposition on the Electrochemical Properties of Ni+MoS<sub>2</sub>+Mo Composite Coatings

The Ni+MoS2+Mo composite coatings were obtained by the electrodeposition under the galvanostatic conditions (jdep= -250 mA cm-2) at the temperature of 30-60°C from the nickel bath containing a suspension of MoS2(<2 μm) and Mo (3-7 μm) powders. 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. The decrease of electrochemical activity towards the HER was found for the Ni+MoS2+Mo composite coatings with the increase in the temperature of their electrodeposition due to decrease of both the intrinsic activity and surface development.

Influence of Surface Development of Ni/W Coatings on the Kinetics of the Electrolytic Hydrogen Evolution

The Ni+W composite coatings were prepared by electrodeposition under the galvanostatic conditions (jdep= -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.

The Hydrogen Evolution Reaction on Ni Electrode Material Modified with Molybdenum(IV) Oxide and Chromium(III) Oxide Powders

The Ni+MoO2and Ni+Cr2O3composite coatings were prepared by the electrodeposition under the galvanostatic conditions (jdep= -200 mA cm-2) from the nickel bath containing powder of MoO2or Cr2O3. Studies of hydrogen evolution reaction (HER) in 5 M KOH solution at room temperature were conducted using steady-state polarization and electrochemical impedance spectroscopy (EIS) methods. It was ascertained that the HER rate is higher for the Ni+MoO2composite electrode in comparison with the Ni+Cr2O3composite electrode due to the presence of Mo in the nickel matrix.

Studies of Metal Dichalcogenide Formation Using Electrochemical ALD

Group VI transition metal dichalcogenides (TMDCs) are graphene-like 2D layered semiconductors that exhibit anisotropic conductivity, which favors conductivity along the basal planes.1 In particular, MoS2, MoSe2 and WSe2 have received special interests for their potential toward photoelectrochemical and photoelectronic applications. These materials have been shown to be viable hydrogen evolution reaction (HER) catalysts in photoelectrochemical water-splitting devices.1-2 Applications in solar energy conversion are feasible due to the direct band gaps these materials possess, which have energies range from near-IR to visible. They are also highly stable against photocorrosion due to the d-d transition that occur upon photoexcitation.3 Among the TMDCs, MoSe2 synthesis and characterization is currently the main focus in this group. In photovoltaic (PV) devices that commonly use Mo as the back contact, having MoSe2 as the intermediate layer between the PV absorber and the Mo back contact may create a more favorable ohmic-type contact that reduces resistive losses.4 A lower resistivity ohmic contact helps to reduce carrier recombination and improves conversion efficiency of a PV device.Formation of MoSe2 nanofilms by electrochemical atomic layer deposition (E-ALD) is currently being investigated by this group. E-ALD can be used to grow high quality nanofilms by alternating precursor solutions through a flow cell to deposit the desired elements up to one atomic layer at a time. Such fine control is possible by utilizing the underpotential deposition (UPD) of elements on each other. Pure Mo electrodeposition is hampered by the presence of HER, but “induced co-deposition” is possible by electrodepositing Mo in the presence of other metal ions.5 In E-ALD of MoSe2, UPD Se plays the role of this other metal ion. Electrochemical studies for growing MoSe2 by E-ALD as well as characterization of preliminary MoSe2 films will be presented.1. Tang, H.; Dou, K. P.; Kaun, C. C.; Kuang, Q.; Yang, S. H., MoSe2 nanosheets and their graphene hybrids: synthesis, characterization and hydrogen evolution reaction studies. J Mater Chem A 2014, 2 (2), 360-364.2. (a) Velazquez, J. M.; Saadi, F. H.; Pieterick, A. P.; Spurgeon, J. M.; Soriaga, M. P.; Brunschwig, B. S.; Lewis, N. S., Synthesis and hydrogen-evolution activity of tungsten selenide thin films deposited on tungsten foils. J Electroanal Chem 2014, 716 (0), 45-48; (b) Jaramillo, T. F.; Jorgensen, K. P.; Bonde, J.; Nielsen, J. H.; Horch, S.; Chorkendorff, I., Identification of active edge sites for electrochemical H-2 evolution from MoS2 nanocatalysts. Science 2007, 317 (5834), 100-102.3. Pathak, V. M.; Patel, K. D.; Pathak, R. J.; Srivastava, R., Improved photoconversion from MoSe2 based PEC solar cells. Sol Energ Mat Sol C 2002, 73 (2), 117-123.4. Wada, T.; Kohara, N.; Nishiwaki, S.; Negami, T., Characterization of the Cu(In,Ga)Se-2/Mo interface in CIGS solar cells. Thin Solid Films 2001, 387 (1-2), 118-122.5. (a) Chandra, S.; Sahu, S. N., Electrodeposited semiconducting molybdenum selenide films. I. Preparatory technique and structural characterisation. Journal of Physics D: Applied Physics 1984, 17 (10), 2115; (b) Delphine, S. M.; Jayachandran, M.; Sanjeeviraja, C., Pulsed electrodeposition and characterization of molybdenum diselenide thin film. Mater Res Bull 2005, 40 (1), 135-147.

MoSe2nanosheets and their graphene hybrids: synthesis, characterization and hydrogen evolution reaction studies

MoSe2 nanosheets and MoSe2/graphene hybrids have been prepared by a facile hydrothermal method. The number of layers of the MoSe2 nanosheets is typically <10 as confirmed directly by transmission electron microscopy and indirectly by a red shift of the characteristic A1g Raman peak. The hydrogen evolution reaction (HER) studies show that the onset potentials of MoSe2 and MoSe2/RGO hybrids are only ∼0.15 V vs. RHE and ∼0.05 V vs. RHE, respectively, about 20–30 mV lower than those of MoS2 and its graphene hybrids reported previously. Density functional theory calculations reveal that the Gibbs free energy for atomic hydrogen adsorption (ΔG0H) on MoSe2 edges is closer to thermoneutral than that on MoS2, with an H coverage of about 75% on the edge under operating conditions, which is also higher than that of MoS2 reported in the literature. The consistency between the experimental and computational results indicates that MoSe2 nanosheets have potential to be a better HER catalyst than their MoS2 counterpart.

Hydrogen evolution reaction at Pd-modified carbon fibre and nickel-coated carbon fibre materials

The present paper reports on A.C. impedance study of hydrogen evolution reaction (HER), carried-out on Pd-modified carbon fibre (CF) and nickel-coated carbon fibre (NiCCF) materials. The HER was examined in 0.5 M H2SO4 solution for electrochemically deposited Pd on Hexcel 12K AS4C CF and Toho-Tenax 12K50 NiCCF tow materials. Kinetics of the hydrogen evolution reaction was studied at room temperature, over the cathodic overpotential range: −100 to −1200 mV vs. RHE. Corresponding values of charge-transfer resistance, exchange current–density for the HER and other electrochemical parameters for the examined catalyst materials were derived. Thus, Pd modification of CF and NiCCF materials (at ca. 1.5 wt.% Pd) dramatically increased the exchange current–density parameter by about 5300× and 445× for carbon fibre and nickel-coated carbon fibre tows, correspondingly.

Study of hydrogen evolution reaction on Ni–P amorphous alloy in the light of experimental and quantum chemistry

The hydrogen evolution reaction (HER) on Ni–P alloys was investigated experimentally and theoretically. First Ni–P alloys with P content in the range from 5.8 to 10.0 wt% were prepared by electrodeposition. The best catalysis to the HER was found on the Ni–P alloys with P content of 6.0 wt% (10.8 at%). In order to understand the function of P element in Ni–P amorphous alloys for the HER, the density-functional theory (DFT) method and front molecular orbital (FMO) theory were used to analyze the function of P element in Ni–P amorphous alloys for the HER. The research shows: it is easier for water molecule to get the first electron and form Ni n +1–H and Ni n P–H on Ni n +1 clusters than on Ni n P clusters, but it is more difficult for water molecule to get the second electron from Ni n +1–H than Ni n P–H. The strength of Ni n +1–H bond is always greater than that of Ni n P–H. It means it is more difficult for hydrogen evolutes from Ni n +1 clusters than Ni n P clusters. Regardless of which step among all steps of the HER is the rate-control step, the Ni–P alloys with P contents being in a range of 9.1–14.3 at% would be always good to the whole HER.

Studies on the hydrogen evolution reaction on different stainless steels

The hydrogen generation by water electrolysis process is a promising technology. The materials commonly utilized for water electrolysis are those based on Raney Nickel and their alloys, but these materials are expensive. We choose a material with nickel presence, more cheap and versatile like stainless steel. In this work, we report the study of hydrogen evolution reaction (her) on different stainless steel electrodes in alkaline solutions (NaOH and KOH). The electrochemical behavior of stainless steel in alkaline medium was studied by cyclic voltammetry. In addition, we designed and developed an alkaline electrohydrolyzer prototype which consists of the anode and cathode electrodes which were made of different types of stainless steel and the electrolyte was KOH. We determined the appropriate electrolyte, stainless steel electrode and voltage for the efficient hydrogen production.

Electrocatalysis of hydrogen evolution reaction on Pt electrode surface-modified by [formula omitted] chemisorption

Kinetic studies of hydrogen evolution reaction (HER) at the surface of Pt in alkaline conditions, reported in this paper, show that electrocatalytic activity is enhanced after adsorption of S - 2 ions. EIS and steady-state polarization curve data pointed to an undoubted improvement in performance with the Pt–S cathode that was attributed to higher adsorbed hydrogen coverage. Experimental findings suggested an increase in the electronic density of the modified surface sites that may strengthen the interaction between H 2O and the adsorption site and, consequently, accelerates the Volmer step.

Study of hydrogen evolution reaction in acid medium on Pt microelectrodes

This work describes the utilization of a Pt UME in the study of the hydrogen evolution reaction in 0.5 M H 2SO 4. A non-linear fitting procedure was employed in order to analyze polarization curves obtained at several temperatures (25–75 °C). The results revealed that the traditionally accepted model described by a Volmer–Tafel route fails to fit the obtained experimental data. In this sense, a new model was proposed involving the Volmer–Heyrovsky mechanism, being the Heyrovsky reaction rate determining step. To achieve the best fit between experimental and calculated data, the kinetic equations had to be proposed with a small value of the transfer coefficient ( β<0.2). This unusual value was associated with an activationless process, which can also justify the limiting kinetic current (not diffusional) observed. Trying to get further insight into this possibility, the polarization studies were also performed on a surface modified by underpotentially deposited copper. With a degree of coverage as high as 0.8, the only observed effect on the polarization curves was a shift towards minor current values. This shift can be completely justified by the blocking of surface area. A change in mechanism was not observed albeit the Cu UPD eliminated the pairs of neighbor active sites necessary to the Volmer–Tafel pathway.