Efficient Catalysts For Hydrogen Generation Research Articles

Enhancing hydrogen generation from sodium borohydride hydrolysis and the role of a Co/CuFe2O4 nanocatalyst in a continuous flow system

In this study, a series of cobalt-based spinel ferrites catalysts, including nickel, cobalt, zinc, and copper ferrites, were synthesized using the sol–gel auto-combustion method followed by a chemical reduction process. These catalysts were employed for accelerating hydrogen generation via the sodium borohydride hydrolysis process. A continuous stirred tank reactor was used to perform catalytic reactor tests. All samples were subjected to analysis using XRD, FESEM, EDX, FTIR, and nitrogen adsorption–desorption techniques. The results revealed that the cobalt-based copper ferrite sample, Co/Cu-Ferrite, exhibited superior particle distribution, and porosity characteristics, as it achieved a high hydrogen generation rate of 2937 mL/min.gcat. In addition, the higher electrical donating property of Cu-Ferrite which leads to the increase in the electron density of the cobalt active sites can account for its superior performance towards hydrolysis of NaBH4. Using the Arrhenius equation and the zero-order reaction calculation, activation energy for the sodium borohydride hydrolysis reaction on the Co/Cu-Ferrite catalyst was determined to be 18.12 kJ/mol. This low activation energy compared to other cobalt-based spinel ferrite catalysts confirms the catalyst's superior performance as well. Additionally, the outcomes from the recycling experiments revealed a gradual decline in the catalyst's performance after each cycle during 4 repetitive cycles. The aforementioned properties render the Co/Cu-Ferrite catalyst an efficient catalyst for hydrogen generation through NaBH4 hydrolysis.

Integrating theory with the nanoreactor concept to synthesize hollow carbon sphere‐encapsulated PtNi alloys for enhanced H2 generation

AbstractThe rational design of efficient bimetallic nanoparticle (NP) catalysts is challenging due to the lack of theoretical understanding of active components and insights into the mechanisms of a specific reaction. Here, we report the rational design of nanoreactors comprising hollow carbon sphere‐confined PtNi bimetallic NPs (PtNi@HCS) as highly efficient catalysts for hydrogen generation via ammonia borane hydrolysis in water. Using both density functional theory calculations and molecular dynamics simulations, the effects of an active PtNi combination and the critical synergistic role of a hollow carbon shell on the molecule diffusion adsorption behaviors are explored. Kinetic isotope effects and theoretical calculations allow the clarification of the mechanism, with oxidative addition of an O–H bond of water to the catalyst surface being the rate‐determining step. The remarkable catalytic activity of the PtNi@HCS nanoreactor was also utilized for successful tandem catalytic hydrogenation reactions, using in situ‐generated H2 from ammonia borane with high efficiency. The concerted design, theoretical calculations, and experimental work presented here shed light on the rational elaboration of efficient nanocatalysts and contribute to the establishment of a circular carbon economy using green hydrogen.

CoP/Co heterojunction on porous g-C3N4 nanosheets as a highly efficient catalyst for hydrogen generation

Designing non-precious catalysts to synergistically achieve a facilitated exposure of abundant active sites is highly desired but remains a significant challenge. Herein, a hetero-structured catalyst CoP-Co supported on porous g-C3N4 nanosheets (CoP-Co/CN-I) was prepared by pyrolysis and P-inducing strategy. The optimal catalyst achieves a turnover frequency (TOF) of 26 min−1 at room temperature and the apparent activation energy (Ea) is 35.5 kJ·mol−1. The catalytic activity is ranked top among the non-precious metal phosphides or the other supports. Meanwhile, the catalytic activity has no significant decrease even after 5 cycles. The CoP/Co interfaces provide richly exposed active sites, optimize hydrogen/water absorption free energy via electronic coupling, and thus improve the catalytic activity. The experimental results reveal that the CoP/Co heterojunction improves the catalytic activity due to the construction of dual-active sites. This research facilitates the innovative construction of non-noble metal catalysts to meet industrial demand for heterogeneous catalysis.

Construction of defective surface structure via hetero atoms (N, S) implantation into waste cypress biomass-derived catalysts for efficient hydrogen evolution reaction

Developing highly efficient hydrogen evolution catalysts with low cost has been a big challenge in industrial applications. Herein, we developed non-metallic heteroatoms doped waste cypress biomass-derived biochar via a facile one-step pyrolysis route. By utilizing defect engineering and charge carriers facilitation, we have constructed appropriated defects with numerous charge carriers for manufacturing efficient catalysts for Hydrogen Evolution Reaction (HER). Through N(0.75), S(0.25)-CBC, we attained a low over-potential value of 122 mV at the current density of 10 mA cm−2 and minimized the Tafel slope value of 112 mV dec−1 in 1 M KOH solution for HER. Furthermore, it attained robust chemical stability of over 50,000 s without any degradation. Hence, this work provides a practical pathway to synthesize cost-effective, non-metallic heteroatoms doped efficient catalysts for hydrogen generation.

Synthesis, characterization, and enhanced hydrogen generation from NaBH4 methanolysis of highly dispersed bimetallic PdNi nanoparticles supported on Vulcan carbon

In this presented work, the bimetallic palladium-nickel nanoparticles (PdNi NPs) supported by Vulcan carbon (VC) were synthesized by chemical method. The morphological structure of the synthesized PdNi@VC NPs was determined by ultraviolet-visible spectrum (UV–Vis), Fourier infrared spectrometry (FTIR), transmission electron microscopy (TEM), and X-ray diffraction (XRD) characterization performed. According to the characterization results obtained, the size of the NPs was found to be 8.523 ± 2.036 nm. Then, hydrogen production efficiencies were tested according to different temperatures, substrate, and catalyst concentrations. Finally, the reusability test was performed. According to the results obtained, the hydrogen average production efficiency of NPs was calculated as 84%. The activation energy (Ea), enthalpy (ΔH), and entropy (ΔS) values of the catalyst were found to be 54.2 kJ/mol, 51.7 kJ/mol, -134.5 J/mol.K, respectively. This study guides the new catalytic energy production studies to be carried out on nanotechnological platforms. These synthesized nanoparticles can be developed to be an efficient catalyst for hydrogen generation as an alternative energy source.

Hierarchical Co3O4/SAPO-34 supported PtCo bimetallic nanoparticles as highly efficient catalyst for hydrogen generation from ammonia borane hydrolysis

Hierarchical Co3O4/SAPO-34 supported PtCo bimetallic nanoparticles (NPs) with uniform dispersion and narrow size-distribution were prepared for the hydrolysis of AB to produce hydrogen. Strategies including the sequential impregnation of cobalt and platinum precursors followed by partial reduction were employed to anchor Pt NPs. Befitting from the interfacial interaction between Co and Co3O4 NPs, the intermetallic synergistic effect of PtCo NPs and the synergistic interaction between Co NPs and SAPO-34 zeolite, the prepared Pt@Co/Co3O4/SP-10(400,2) catalyst exhibited outstanding catalytic activity with a high turnover frequency (TOF) value of 314 molH2(molPt·min)-1 at 303 K. In addition, the flake-assemble hierarchical structure of SAPO-34 played an important role in improving the dispersion of metal NPs and the mass transfer rate between reactants and active sites.

Cobalt ferrite nanoparticles anchored on reduced graphene oxide nanoribbons (0D/1D CoFe2O4/rGONRs) as an efficient catalyst for hydrogen generation via NaBH4 hydrolysis

For better performance of nanoparticles as the heterogeneous catalyst, various materials with a large surface area have been introduced as the substrate. Herein, CoFe2O4 nanoparticles were anchored on carbon nanotubes (CoFe2O4/CNTs) and graphene nanoribbons (CoFe2O4/GONRs) to investigate the influence of substrate in the catalytic performance. These nanocomposites were evaluated in a NaBH4 hydrolysis reaction to produce hydrogen. The results showed that the highest hydrogen volume occurs in the presence of CoFe2O4/GONRs nanocatalyst. Abundant oxygen-based functional groups at the edges of GONRs offered excellent sites for CoFe2O4 nanoparticles and improved catalytic performance. Under optimum conditions (2.0 wt% of NaBH4, 15 mg of catalyst, 2.0 wt% of NaOH), the hydrogen generation rate was found to be 3.7 L g-1min−1 at 35 °C. The activation energy was calculated using the Arrhenius method, equivalent to 31.4 kJ mol−1. Therefore, CoFe2O4/GONRs catalyst can be a novel and efficient candidate for hydrogen production as a clean fuel.

Electronic transfer enhanced coral-like CoxP loaded Ru nanoclusters as efficient catalyst for hydrogen generation via NaBH4 hydrolysis

The slow kinetics of NaBH4 hydrolysis to generate hydrogen can be effectively improved by designing the composite catalysts of precious metals and transition metals, while their micro-combined structure still needs to be improved. Herein, the coral-like CoxP with high specific surface area is fabricated by ZIF-67 in-situ etching, annealing, phosphating and loading in turns, 1.5 nm Ru nanocluster species are uniformly loaded on the skeleton surface of CoxP, and there is the strong electronic effect between Ru and CoxP. By further adjusting the loading of Ru, the optimized Ru3.4@CoxP catalyst has lower activation energy (32.8 kJ mol−1) than CoxP, and displays higher turnover frequency (606molH2min−1molRu−1) and hydrogen generation rate (4551mLmin−1gcatalyst−1) than the comparative and most reported similar catalysts during NaBH4 hydrolysis. Furthermore, After five cycles, the catalytic activity of Ru3.4@CoxP is only reduced by 25.6%. The excellent catalytic activity is due to the micro-nano structure with high specific surface area and the synergistic effect between Ru and Co species providing more catalytic active sites, which is the precise and controllable design method for developing noble metal/transition metal composite catalyst.

Nitrogen-doped carbon encapsulated Ru-decorated Co2P supported on graphene oxide as efficient catalysts for hydrogen generation from ammonia borane

Developing high-performance hydrogen generation/storage materials and technologies is an essential step for applying hydrogen-oxygen fuel cells under the background of carbon peak and carbon neutralization strategy. Ammonia borane (NH3BH3, AB) features a high volumetric and gravimetric density of hydrogen, showing great potential for chemical hydrogen storage. Exploring low-cost and high-efficiency catalysts is an essential prerequisite for hydrogen generation through AB hydrolysis under mild conditions. Herein, with rationally designing Ru/Co metal-organic framework (RuCo-MOF), a series of Co2P nanoparticles doping with low-content Ru embedded in nitrogen-doped carbon supported on graphene oxide (Ru-Co2P@N-C/GO) were synthesized via a one-pot phosphorization process. Benefiting from the unique structure and the electronic structure regulation of Ru, Ru-Co2P@N-C/GO exhibits excellent catalytic performance with an original turnover frequency (TOF) of 347.3 molH2 molRu–1 min–1 and an excellent specific rate (rB) of 83,929 mL min–1 gRu–1 toward AB hydrolysis. This work opens a new avenue toward developing effective and economic catalysts for AB hydrolysis.

Functional Group Regulated Ni/Ti3C2Tx (Tx = F, -OH) Holding Bimolecular Activation Tunnel for Enhanced Ammonia Borane Hydrolysis.

Developing economical and efficient catalyst for hydrogen generation from ammonia borane (AB) hydrolysis is still a huge challenge. As an alternative strategy, the functional group regulation of metal nanoparticles (NPs)-based catalysts is believed to be capable of improving the catalytic activity. Herein, a series of Ni/Ti3C2Tx-Y (Tx = F, -OH; Y denotes etching time (d)) catalysts are synthesized and show remarkably enhanced catalytic activity on the hydrolysis of AB in contrast to the corresponding without regulating. The optimized Ni/Ti3C2Tx-4 with a turnover frequency (TOF) value of 161.0 min-1 exhibits the highest catalytic activity among the non-noble monometallic-based catalyst. Experimental results and theory calculations demonstrate that the excellent catalytic activity benefits from the bimolecular activation channels formed by Ni NPs and Ti3C2Tx-Y. H2O and AB molecules are activated simultaneously in the bimolecular activation tunnel. Bimolecular activation reduces the activation energy of AB hydrolysis, and hydrogen generation rate is promoted. This article provides a new approach to design effective catalysts and further supports the bimolecular activation model for the hydrolysis of AB.

Magnetically recyclable Co2P nanosheets as highly efficient catalysts for hydrogen generation from hydrolysis of sodium borohydride

A facile strategy was developed for the preparation of magnetically recyclable Co2P nanosheets with efficient catalytic activity for NaBH4 hydrolysis.

Ni–Mo2C Nanocomposites as Highly Efficient Catalysts for Hydrogen Generation from Hydrolysis of Ammonia Borane

Ni–Mo₂C Nanocomposites as Highly Efficient Catalysts for Hydrogen Generation from Hydrolysis of Ammonia Borane

Sulphonated silica and sulphonated silica / carbon particles as efficient catalysts for hydrogen generation from sodium borohydride hydrolysis

In the present study, silica, sulphonated silica (SS) and sulphonated silica/carbon (SSC) particles are prepared by sol-gel method using tetra-ethyl ortho-silicate and glucose as sources for silica and carbon, respectively and used as catalysts for sodium borohydride (NaBH4) hydrolysis to produce hydrogen. The acid density calculated by back titration method shows the acidic nature of SS and SSC. Further, the catalysts are characterized using FT-IR, XRD, SEM, TEM, EDAX and N2 physisorption studies. TEM and N2 adsorption/desorption studies revealed the porous nature of the particles. Further, the catalytic activities of SS and SSC are analysed towards NaBH4 hydrolysis. It is found that both SS and SSC enhance the sodium borohydride hydrolysis significantly with hydrogen generation rates of 768 and 914 mL min−1 g−1, respectively. Using Arrhenius plot, the activation energies of SS and SSC are calculated as 24.74 and 18.97 kJ mol−1, respectively. Further, thermodynamic parameters like ΔH‡, ΔS‡ and ΔG‡ of the activated complex are calculated using Erying plot. The negative ΔS‡ value suggests that the mechanism of NaBH4 hydrolysis at SS and SSC follows Langmuir-Hinshelwood associative mechanism.

PVP-stabilized platinum nanoparticles supported on modified silica spheres as efficient catalysts for hydrogen generation from hydrolysis of ammonia borane

Ammonia borane (AB) is considered to be a promising solid hydrogen carrier. In this work, poly(N-vinyl-2-pyrrolidone) (PVP)-protected platinum nanoparticles are supported on γ-methacryloxypropyltrimethoxysilane (γ-MPS) modified silica spheres (Pt-PVP/SiO2(M)), which are firstly used as highly efficient catalysts for hydrolysis of AB. Platinum nanoparticles possess a tiny size of 2–3 nm and are uniformly dispersed over modified silica spheres. Pt-PVP/SiO2(M) catalysts with a Pt loading amount of 1.30 wt% show the highest catalytic activity with a turnover frequency (TOF) value of 371 molH2 molPt−1 min−1 (866 molH2 molPt−1 min−1 corrected for the surface atoms) at 25 °C. The activation energy is calculated to be 46.2 kJ/mol. Furthermore, owing to the synergistic effect between the modifier of silica spheres and the capping agent of metal nanoparticles, Pt-PVP/SiO2(M) catalysts have a higher loading amount (8.7 and 6.5 times) and TOF value (4.8 and 5.5 times) than the counterparts prepared without γ-MPS and PVP, respectively.

A Review and Perspective on Electrocatalysts Containing Cr for Alkaline Water Electrolysis: Hydrogen Evolution Reaction

Transition metal-based catalysts are the next most efficient catalysts for hydrogen generation in alkaline media, after Pt-group metal catalysts. Research employing transition metal-based catalysts has progressed exponentially in recent years, resulting in catalysts with excellent activity and stability. Compared to other neighbour d-metals (Ni, Fe, Co, Cu) which receive proper preference, research on Zn, Mn, and Cr containing electrocatalysts for water electrolysis is limited. Chromium in general has received limited consideration but has begun to attract the attention of researchers in the past few years. This review provides a brief discussion and evaluation of different catalysts (oxides, hydroxides, nitrides, phosphides, sulphides, carbides, etc.) incorporating different phases of the Cr component, together with a perspective on the catalytic significance of using Cr as a co-catalyst for hydrogen evolution in alkaline media. With advancements in catalysis research, electroactivity and stability showcased by Cr-based catalysts, some even competitive against precious metal catalysts, can be lucrative solutions for H2 generation.

Nano-structured Ni-based Active Species Supported on Metallic Substrates as the Efficient Catalysts for Hydrogen Generation from Methane with Water

Nanostructured Ni metal and Ni-Re alloy active species supported on the surface of the total metallic Ni honeycomb substrate and the porous Ni metal substrate are studied as the novel catalyst system for hydrogen generation from steam methane reforming. The bimetallic Ni-Re nano-alloy active species on the surface of the metallic Ni honeycomb substrate or porous Ni metal substrate exhibit the remarkably enhanced activity for steam methane reforming to generate hydrogen especially at lower reaction temperatures. The total metallic catalysts with excellent electric and heat conductivity and almost zero bed pressure loss are expected to be used for the innovation industrial processes.

CeO2 supported multimetallic nano materials as an efficient catalyst for hydrogen generation from the hydrolysis of NaBH4

Nowadays, there is still no suitable method to store large amounts of energy. Hydrogen can be stored physically in carbon nanotubes or chemically in the form of hydride. In this study, sodium borohydride (NaBH4) was used as the source of hydrogen. However, an inexpensive and useful catalyst (Co–Cr–B/CeO2) was synthesized using the NaBH4 reduction method and its property was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), x-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) measurements. The optimized Co–Cr–B/CeO2 catalyst exhibited an excellent hydrogen generation rate (9182 mLgmetal−1min−1) and low activation energy (35.52 kJ mol−1). The strong catalytic performance of the Co–Cr–B/CeO2 catalyst is thought to be based on the synergistic effect between multimetallic nanoparticles and the effective charge transfer interactions between the metal and the support material.

NiPt Nanoparticles Anchored onto Hierarchical Nanoporous N-Doped Carbon as an Efficient Catalyst for Hydrogen Generation from Hydrazine Monohydrate.

Catalytic decomposition of the hydrogen-rich hydrazine monohydrate (N2H4·H2O) represents a promising hydrogen storage/production technology. A rational design of advanced N2H4·H2O decomposition catalysts requires an overall consideration of intrinsic activity, number, and accessibility of active sites. We herein report the synthesis of a hierarchically nanostructured NiPt/N-doped carbon catalyst using a three-step method that can simultaneously address these issues. The chelation of metal precursors with polydopamine and thermolysis of the resulting complexes under reductive atmosphere resulted in a concurrent formation of N-doped carbon substrate and catalytically active NiPt alloy nanoparticles. Thanks to the usage of a silica nanosphere template and dopamine precursor, the N-doped carbon substrate possesses a hierarchical macroporous-mesoporous architecture. This, together with the uniform dispersion of tiny NiPt nanoparticles on the carbon substrate, offers opportunity for creating abundant and accessible active sites. Benefiting from these favorable attributes, the NiPt/N-doped carbon catalyst enables a complete and rapid hydrogen production from alkaline N2H4·H2O solution with a rate of 1602 h-1 at 50 °C, which outperforms most existing catalysts for N2H4·H2O decomposition.

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.

Ru Nanoparticles Embedded in Cubic Mesoporous Silica SBA-1 as Highly Efficient Catalysts for Hydrogen Generation from Ammonia Borane

Cubic mesoporous silica SBA-1 functionalized with carboxylic acid (-COOH), namely S1B-C10, is used as a support to fabricate and confine Ru nanoparticles (NPs). The uniformly dispersed organic functional groups in SBA-1 are beneficial in attracting Ru cations, and as a result, homogenously distributed small sized Ru NPs are formed within the mesopores. The prepared Ru@S1B-C10 is utilized as a catalyst for H2 generation from the hydrolysis of ammonia borane (AB). The Ru@S1B-C10 catalyst demonstrates high catalytic activity for H2 generation (202 mol H2 molRu min−1) and lower activation energy (24.13 kJ mol−1) due to the small sized Ru NPs with high dispersion and the support’s interconnected mesoporous structure. The nanosized Ru particles provide abundant active sites for the catalytic reaction to take place, while the interconnected porous support facilitates homogenous transference and easy dispersal of AB molecules to the active sites. The catalyst demonstrates good recycle ability since the accumulation and leaking of NPs throughout catalysis can be effectively prevented by the support.