Catalytic Activity For Hydrogen Generation Research Articles

Synthesis of azo polymers and their catalytic performance in hydrogen production via NaBH4 methanolysis

The extensive use of fossil fuels has a profound impact on ecosystems and contributes to global warming through the emission of greenhouse gases. To mitigate these effects, alternative energy sources such as hydrogen are crucial. In this study, a green synthesis approach was used to prepare an azo cross-linked polymer containing 4-aminophenyl ether and resorcinol. The synthesized polymer was thoroughly characterized by FT-IR, BET, TGA, Zeta Potential and SEM-EDS analyses. The catalytic performance of the polymer in hydrogen production from NaBH4 via methanolysis was then investigated. Various parameters affecting hydrogen production, including catalyst and NaBH4 amounts, methanol volume and temperature, were systematically investigated to identify the optimum conditions. The polymer exhibited maximum hydrogen generation rate (HGR) of 12,619 mL H2 min⁻¹ gcat⁻¹ at 60 °C, respectively, with an activation energy of 24.22 kJ mol⁻¹. After optimization, the reusability of the polymer was evaluated over five cycles and the theoretical hydrogen generation rates were consistently achieved; however, the hydrogen generation time increased with each subsequent cycle. The primary objective of this research was to highlight novel azo linked polymers with potent catalytic activity in hydrogen generation, demonstrating the significant potential of the polymer to advance hydrogen generation. Ultimately, this study highlights the promising role of azo cross-linked polymers as effective catalysts for hydrogen production, offering new avenues and perspectives towards sustainable energy solutions.

Fabrication of multiatomic structure of Cu-CoO/Co interface for efficient hydrogen generation from ammonia borane hydrolysis

Hydrogen generation from hydrolysis of ammonia borane is a secure and promising route for conversion of hydrogen energy. Preparation of efficient and economical catalysts is highly required for the development hydrogen economy. In this study, the Co-based catalysts with multiatomic structure were designed for hydrolysis of ammonia borane reaction. The synergistic effect between Co and M (M = Cu, Ni, Fe) greatly enhanced the catalytic performance of bimetallic catalysts. The TOF value of CoCu-NC-5 towards 8.12 min−1 is 7 times that of the single Co catalyst. Moreover, The CoCu catalysts showed the stronger synergistic effect and highest catalytic activity for hydrogen generation, compared with CoNi and CoFe catalysts. The TOF value of CoCu-NC-5 is 2.3 and 6.0 times that of CoFe-NC-5 and CoNi-NC-5 catalysts, respectively. The active component structure of Cu-CoO/Co interface in CoCu-NC-5 is beneficial for activation and dissociation of water molecule due to the strong electron transfer effect and positive synergy. The activation energy over CoCu-NC-5 is 34.25 kJ mol−1, and the catalyst exhibited good stability. This work provides a feasible method for rational design of efficient catalysts with hierarchical structure for conversion of energy.

Cobalt decorated egg-shell-type activated carbon pellets: Catalytic application in hydrogen release from boron based solid fuel

Hydrogen became zero-carbon fuel used in fuel-cell or internal combustion engines, regard- ing energy sector green-hydrogen also has become an energy carrier in commercial appli- cations. For supporting decarbonization strategies based on hydrogen, boron-fuels are good options to safely store for mobile technologies. Ammonia borane (NH3BH3) is the one of the boron based fuels that stored 19.6 wt.% H2 in its structure chemically. Cobalt (Co) decorated egg-shell-type activated carbon pellets were synthesized for catalytic application of hydrogen release from NH3BH3. Two different sized pellet type activated carbon was decorated with co- balt by combined procedure as modified vacuum-impregnation method with heat fixation and reduction. The obtained catalysts were characterized by applying optical microscope (OM), scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDS), transmis- sion electron microscopy (TEM), nitrogen sorption based surface analyses (BET). Activated carbon provides porous structure for effectively dispersion Co particles while the outer shell shows the catalytic activity for hydrogen generation. Structural characterization results and preliminary activity tests confirmed that fabricated Co@ACPB exhibited better performance compared with Co@ACPS catalysts thanks to thinner shell thickness and higher BET surface area/pore volume properties. The results of the kinetic study showed the core-shell type Co based catalyst catalyzed the reaction and follows the zero-order reaction kinetic model with 41.78 kJmol-1. Activated carbon pellets provide well dispersion and stability of active Co sites, easy separation of used catalysts after the reaction and enable practical regeneration of cata- lytic materials.

Construction of amorphous Fe0.95S1.05 nanorods with high electrocatalytic activity for enhanced hydrogen evolution reaction

Amorphous catalysts with abundant defects are attractive for electrocatalytic water splitting. In this work, amorphous Fe0.95S1.05 (a-FeS) nanorods are synthesized by a facile solvothermal method using octylamine solvent and employed as a low-cost and highly active electrocatalyst towards efficient hydrogen evolution reaction (HER). The capped octylamine molecules are responsible for formation of the amorphous structure. The disordered atomic arrangement with plenty of unsaturated atoms endows the a-FeS nanorods with extensive defects as exposed catalytic sites. Compared with the crystalline Fe0.95S1.05 (c-FeS) nanorods, the a-FeS nanorods exhibit a larger electrochemical active surface area and more remarkable catalytic activity. Consequently, excellent HER performance of a small Tafel slope of 43 mV dec−1, a low overpotential of 67 mV at the current density of 10 mA cm−2, and a long operation stability of 80 h is achieved for a-FeS. This work demonstrates the best catalytic activity for hydrogen generation among iron sulfide-based catalysts to date.

A nickel(II) complex of 2,6-pyridinedicarboxylic acid ion, an efficient electro-catalyst for both hydrogen evolution and oxidation

A new electrocatalyst based on a nickel complex, [Ni(HL)2], is designed and provided by the reaction of NiCl2 with 2,6-pyridinedicarboxylic acid (H2L) in our group. Electrochemical investigations show that [Ni(HL)2] can electro-catalyze hydrogen evolution from acetic acid with a rate constant of 3454 M−2 s−1. [Ni(HL)2] also can electro-catalyze hydrogen oxidation with a rate constant of 2.047 × 104 M−2 s−1. The carboxyl group of [Ni(HL)2] may play critical roles in the catalytic hydrogen evolution and oxidation reactions. Moreover, the introduction of an electron-withdrawing group, -Cl at the pyridine of H2L leads to a decrease in the catalytic activity for hydrogen generation, and [Ni(HL)2] shows a more efficient activity than [Ni(HL-Cl)2] (H2L-Cl: 4-chloro-2,6-pyridinedicarboxylic acid). These findings can afford a new ideal for the design of electrocatalysts for both H2 evolution and H2 oxidation.

Cu-based tri-metallic nanoparticles with noble metals (Ag, Pd, and Ir) and their catalytic activities for hydrogen generation

The growth of simple and cost effective heterogeneous catalysts for the release of hydrogen is the key technological challenge for the fuel-cell based hydrogen economy. Stepwise metal displacement plating method was used for the fabrication of Cu0-based nanoparticles, Cu–Ag–Ir, Cu–Pd–Ir, and Cu–Ag–Pd to generate hydrogen from hydrazine hydrogen storage material. The preliminary indications of CuNPs production were the appearance of red-chocolate color with NaBH4, sodium dodecyl sulfate (SDS) under light emitting diode (LED) irradiation. Ag and Pd were deposited on the surface of Cu0 by rapid reduction with NaBH4 in SDS. Catalytic activity of trimetallic (Cu–Pd–Ir, Cu–Ag–Ir, Cu–Ag–Pd)) were higher than that of bimetallic (Cu–Ag, Cu–Ir, and Cu–Pd) due to the synergistic effect and electron interactions between the three metals. The catalytic performance of these materials depends on the structure of outer, and middle metal layers over a Cu inner metal. The nessler's reagent solution was employed to trap ammonia formation along with evolution of hydrogen generation. Cu25–Pd25–Ir50 exhibited the superior catalytic activity, with rate constant of 5.6 × 10−4 s−1 at 303 K, activation energy of 32 kJ/mol, activation enthalpy of 30 kJ/mol, and turn over frequency of 350 h−1.

Synthesis of ternary nanoparticles using the complexation-reduction method and their catalytic activities for hydrogen generation from formic acid

A complex-reduction method was used for the synthesis of glycine-capped copper nanoparticles (Gly-CuNPs). Glycine-Cu2+ was prepared at room temperature, and the resulting complex was treated with NaBH4. Gly-Cu/Ag and Gly-Cu/Ag/MnO2 were prepared by using the stepwise metal displacement plating method. Gly-Cu, Gly-Cu/Ag and Gly-Cu/Ag/MnO2 were employed as catalysts for hydrogen generation from the decomposition of formic acid. The alkaline barium hydroxide solution was employed to trap CO2 formation, and pseudo-first-order rate constants were calculated by using the kobs = 2.303/t log(Aα-A0/Aα-At) relation. Hydrogen generation followed fractional order kinetics with formic acid, and various kinetic parameters were calculated for various concentrations of promoter (sodium format), catalyst and temperature. The catalytic activity was found to increase with an increasing number of incorporated metals, and the order of reactivity was as follows: Gly-Cu/Ag/MnO2 > Gly-Cu/Ag > Gly-Cu. For Gly-Cu/Ag/MnO2, the values of activation parameters (Ea = 56 kJ/mol, ∆H# = 53 kJ/mol, ∆S# = − 68 J/K/mol) were determined with the Arrhenius and Eyring equations, which show higher catalytic efficiency than that of Gly-Cu/Ag (Ea = 69 kJ/mol, ∆H# = 66 kJ/mol, ∆S# = − 25 J/K/mol) due to the synergistic effect and strong interactions between the three metals. The catalytic stability and recyclability were excellent for five consecutive cycles, but the stability and recyclability decreased due to the higher reactivity of MnO2 NPs.

Facile synthesis of agglomerated Ag–Pd bimetallic dendrites with performance for hydrogen generation from formic acid

We report a simple method for the fabrication of agglomerated Ag–Pd bimetallic dendrites by the addition of NaCOOH. The agglomerated Ag–Pd bimetallic dendrites are characterized SEM, TEM, XRD and XPS measurements. The prepared Ag–Pd bimetallic dendrites exhibited catalytic activity in hydrogen generation from decomposition of formic acid at room temperature (~25 °C). Herein, the present Ag–Pd bimetallic dendrites possess the new type of agglomerated structure against to dispersion, which make them easily separated from the reaction system. It is convenient for operator to cease catalytic reaction at any moment. Moreover, the resulting Ag–Pd bimetallic dendrites can be easily reactivated simply by drying after water cleaning for reuse, which saved the cost of catalysts. Among them, Ag1Pd1 sample showed nice performance of recycle test and long lifetime for the decomposition of formic acid at room temperature.

Hydrogen Generation from an Alkaline NaBH4 Solution Using Different Cobalt Catalysts

The effective Co, CoB and CoBM, where M = Mo, Zn, and Fe, catalysts have been deposited on the Cu surface by a simple electroless metal deposition method using morpholine borane as a reducing agent and used as catalysts for hydrogen generation from an alkaline NaBH4 solution. The catalytic activity of different cobalt alloys catalysts towards the hydrolysis of NaBH4 has been investigated by measuring the amount of generated hydrogen from an alkaline solution contained 5 wt. % NaBH4 and 0.4 wt. % NaOH. The rate of H2 generation has been measured at solution temperatures in the range from 298 to 318 K in order to determine the activation energy.It has been determined that the synthesized Co/Cu, CoB/Cu and CoBM (M=Mo,Zn,Fe)/Cu catalysts demonstrate the catalytic activity for the hydrolysis reaction of NaBH4. The lowest obtained activation energy of the hydrolysis reaction of NaBH4 has been 27 kJ mol-1 for the CoBMo/Cu catalyst. The hydrogen generation rate has been achieved 15.30 ml min-1 using the CoBMo/Cu catalyst at a temperature of 313 K and it increases ~3.5 times with the increase of temperature to 343 K. Moreover, the CoBMo/Cu catalyst shows a highest catalytic activity for hydrogen generation from the alkaline NaBH4 solution as compared with that for other Co/Cu, CoB/Cu, CoBZn/Cu, and CoBFe/Cu catalysts.

Synthesis and high catalytic activity of ISOBAM-104 stabilized Fe colloidal catalysts for hydrogen generation

ISOBAM-104 stabilized Fe colloidal catalysts were synthesized by in-situ reduction method for hydrogen generation from KBH4 hydrolysis in alkaline solutions. The as-prepared non-noble metal colloidal catalysts contained Fe nanoparticles with an average size of around 1.9 nm as well as uniformly dispersed single Fe atoms, exhibiting a high catalytic activity of 8100 mL-H2 min−1 g-Fe−1, which was higher than that of the Fe catalysts prepared by other protective agents. Such high catalytic activity of the as-synthesized Fe colloidal catalysts could be ascribed to the following two factors: (1) the in-situ formed and well-dispersed Fe atoms that were confirmed by HAADF-STEM, and (2) the superior protective ability of ISOBAM-104 compared with other protective agents, which was validated by a density functional theory (DFT). In addition, the apparent activation energy of Fe colloidal catalysts was 49.85 kJ mol−1, which was in coincidence with DFT calculation results (49.7 kJ mol−1) and lower than most other Fe-based catalysts, implying that the as-prepared Fe colloidal catalyst is a promising candidate for the catalytic hydrolysis of KBH4. This study could provide a promising approach to prepare non-noble metal colloidal catalysts with excellent catalytic activity for hydrogen generation.

Novel highly active Ni–Re super-alloy nanowire type catalysts for CO-free hydrogen generation from steam methane reforming

Novel Ni–Re super-alloy nanowire type catalyst system is found for hydrogen generation from steam methane reforming. The novel nanowire type catalysts exhibit the super-high catalytic activity for hydrogen generation from steam methane reforming with CO-free in the product at lower reaction temperatures. The Ni–Re alloy nanowire type catalysts are active for converting methane and water to hydrogen and carbon dioxide at a low reaction temperature of about 623 K, which is about 200 K lower than that is needed for steam methane reforming on the conventional catalysts. The CO-free hydrogen is efficiently generated from steam methane reforming on the nanowire type catalysts at the lower reaction temperatures, in which water–gas shift reaction step is not needed for CO-free hydrogen production.

Salts Induced Formation of Hierarchical Porous ZIF‐8 and Their Applications for CO2 Sorption and Hydrogen Generation via NaBH4 Hydrolysis

AbstractDespite the great potential of two different pore regimes (hierarchical porous (HP) structure), HP‐zeolitic imidazolate frameworks‐8 (HPZIF‐8) can be efficient catalysts for hydrogen generation via hydride hydrolysis, and as adsorbents for CO2 gas adsorption. Herein, HPZIF‐8, and leaf‐like ZIF (ZIF‐L) are synthesized via a simple and environmentally friendly procedure using layered hydroxide nitrate of zinc (Z5HN) as a metal source and simple inorganic salt as a modulator. Z5HN nanosheets undergo topotactic transformation to simonkolleite (Zn5(OH)8Cl2·H2O) that can be converted to the pure phase of HPZIF‐8. The concentration of the salts tunes the textural properties of the final product. Applications of HPZIF‐8 and ZIF‐L for CO2 sorption exhibit excellent adsorption properties with increases of 25% due to the presence of cations in the frameworks. ZIF‐8 shows exceptional high catalytic activity for hydrogen generation via the hydrolysis of sodium borohydride. The simple synthesis of ZIF‐8 as well as their good performance as adsorbent and catalyst ensure the potential for industrial and commercial uses.

ISOBAM-stabilized Ni2+ colloidal catalysts: high catalytic activities for hydrogen generation from hydrolysis of KBH4

ISOBAM-104-stabilized Ni2+ colloidal catalysts were synthesized through a facile method and used for hydrogen generation from hydrolysis of potassium borohydride (KBH4). Ni nanoparticles (NPs) were formed as the active phase during the catalytic process. Ultraviolet–visible spectrophotometry (UV–vis) and transmission electron microscopy were employed to characterize the structure and particle size of the as-formed Ni NPs. The results suggested that the catalytic activity of Ni2+ colloidal catalyst increased with the decreased size of as-formed Ni NPs, which is consistent with the results of density functional theory calculation. The highest catalytic activity of the catalyst can be 12400 ml-H2 min−1 g-Ni−1, which was even higher than that of noble Pt or Pd colloidal catalysts prepared using identical methods and catalytic conditions. According to the Arrhenius method, the ISOBAM-104-stabilized Ni2+ colloidal catalysts showed low activation energies of about 41.3 kJ mol−1 for the hydrogen generation from hydrolysis basic KBH4 solution.

Colloidal Co single-atom catalyst: a facile synthesis strategy and high catalytic activity for hydrogen generation

A facile route for on-demand hydrogen production via simply controlling the mixing process of a KBH4 solution and an aqueous solution of ISOBAM-104 stabilized Co2+ ions.

Palladium Supported on Porous Chitosan-Graphene Oxide Aerogels as Highly Efficient Catalysts for Hydrogen Generation from Formate.

Adsorption of Pd(NH3)42+ in preformed chitosan–graphene oxide (CS-GO) beads and their subsequent reduction with NaBH4 afford well-dispersed, high dispersion (~21%) of uniformly sized Pd nanoparticles (~1.7 nm). The resulting Pd/CS-GO exhibits interesting catalytic activity for hydrogen generation by ammonium formate decomposition. The optimal GO proportion of 7 wt% allows reaching, at 60 °C, a turnover frequency above 2200 h−1—being outstanding among the highest values reported for this process to date. Interestingly, no formation of CO or CH4 was detected. The catalyst did not leach, although it underwent gradual deactivation, probably caused by the increase in the Pd average size that became over 3 nm after three uses. Our results are relevant in the context of efficient on-board hydrogen generation from liquid organic hydrogen carriers in transportation.

An effective amino acid-assisted growth of ultrafine palladium nanocatalysts toward superior synergistic catalysis for hydrogen generation from formic acid

An amino acid-assisted approach is developed to immobilize ultrafine Pd NPs onto mesoporous carbon, which exhibits remarkable catalytic activity for hydrogen generation.

Fabrication of quantum Cu(II) nanodot decorated TiO2 nanotubes by the photochemical deposition-assisted hydrothermal method: study catalytic activity in hydrogen generation

Fabrication of quantum Cu(II) nanodot decorated TiO2 nanotubes by the photochemical deposition-assisted hydrothermal method: study catalytic activity in hydrogen generation

Hydrogen Production from the Decomposition of Formic Acid over Carbon Nitride‐Supported AgPd Alloy Nanoparticles

AbstractHighly dispersed bimetallic AgPd alloy nanoparticles with various ratios have been supported on carbon nitride by using a co‐reduction method and then tested for catalytic dehydrogenation of formic acid without base addictive. It was found that the activity of the catalyst depended directly on the AgPd ratios of the catalyst and the reaction temperature. The Ag1Pd2/CN catalyst exhibited excellent catalytic activity for hydrogen generation from formic acid with the initial TOF of 621 h−1 at 348 K. The synergetic interaction between the bimetallic AgPd nanoparticles and the carbon nitride support, the AgPd ratio and the dispersion of AgPd nanoparticles on the support contribute to the high catalytic performance of the AgPd/CN catalysts.

Nanoporous CeO2 Supports Prepared from Amorphous Alloys: Enhanced Catalytic Performance for Hydrogen Generation from Formic Acid

Abstract Nanoporous CeO2 samples as supports were prepared by chemical dealloying Ce-Al amorphous alloy, followed by synthesis of Au-Pd/CeO2 catalysts. The synthesized Au-Pd/CeO2 catalysts showed higher catalytic activity for hydrogen generation from formic acid than catalysts using supports prepared from a crystalline alloy precursor.

Highly Dispersed Surfactant-Free Amorphous NiCoB Nanoparticles and Their Remarkable Catalytic Activity for Hydrogen Generation from Ammonia Borane Dehydrogenation

The effective storage and generation of hydrogen at room temperature is an important issue in many areas, including alternative energy. In this work, NiCoB nanoalloys with high B contents, clean surfaces, and good dispersions are synthesized by an in-situ reduction method. The NiCoB catalyst with high B content exhibits significantly more excellent catalytic activity for hydrogen generation from the hydrolytic of ammonia borane than NiCoB catalyst with low B content. The remarkable catalytic performance is attributed to the strong electronic interaction between the incorporated B and the active metal sites of Co and Ni, the clean surface and good dispersion of the catalyst. Basically, the physical and catalytic properties of the catalyst take advantage of the selection of reductant used during the in-situ synthesis of the NiCoB nanoalloys. This work demonstrates that this facile synthetic method is a promising avenue for the rational design of various B incorporated metal catalysts for hydrogen energy exploitation, metal/air batteries, and electrochemical sensors.