Efficient Catalyst For Hydrogen Production Research Articles

CuMOF@Faujasite nanocomposite as a novel catalyst for hydrogen production

Energy production is one of the most crucial issues presently attracting global attention. In this work, a CuMOF@Faujasite nanocomposite was synthesized and utilized as a novel efficient catalyst for hydrogen production. The produced composite was first characterized using X‐ray diffraction (XRD), Fourier‐ transform infrared (FT‐IR), thermogravimetric analysis (TGA), and differential scanning calorimetry. Surface properties were analyzed via nitrogen adsorption–desorption isotherms. All characterization results revealed the formation of a pure and well‐defined crystalline phase, with a high specific surface area (SBET) of 286 m2/g (SBET of Faujasite is 35 m2/g). Moreover, the morphology and compositional analysis of the nanocomposite were assured through the scanning (SEM) and transmission (TEM) electron microscope and X‐ray photospectroscopy (XPS). SEM and TEM images revealed sponge‐like spheres that are related to Faujasite besides small spherical particles related to CuBDC MOF. XPS analysis revealed a low content of CuMOF in the nanocomposite. The catalytic activity of the nanocomposite was tested for the dehydrogenation of NaBH4. The impact of NaBH4 concentration, weight of the catalyst, and the reaction temperature on NaBH4 hydrolysis was investigated. A hydrogen generation rate (HGR) of 484 mLmin−1 g−1 at 30 °C was achieved using 50 mg of the catalyst and 0.05 mol/l of NaBH4 owing to the high specific area and the selective active sites for such hydrolytic reaction. The kinetic analysis of the activity data indicates the first‐order behavior at low concentrations of NaBH4. Furthermore, at concentrations ≥0.065 mol L−1, zero‐order kinetics was predominant. The time needed for completion of the hydrolysis reaction was found to be decreased (~20 min) by increasing the catalyst mass as well as NaBH4 concentration or even by elevating the reaction temperature (~4 min at 60 °C). The activation energy was estimated; it was found to be 70.5 KJ mol−1. Ultimately, our catalyst showed a reasonable rate of hydrogen production, as compared to others reported earlier.

HER catalytic activity and regulation of a transition metal atom-anchored BC3 monolayer: a first-principles study.

An atomic-level understanding of the hydrogen evolution reaction (HER) on a transition metal (TM) atom-anchored 2D monolayer is vital to explore highly efficient catalysts for hydrogen production. Here, the catalytic activities and modulation of TM atom (Ti, Fe, Cu, Zn, Mo, Ag, Au)-doped BC3 monolayers are investigated by first-principles calculations. Au@BC3 and Fe@BC3 are proven to be potentially excellent HER catalysts. Partial oxidation engineering on Zn@BC3 could improve its performance. Au@BC3 and Ti, Cu and Mo-anchored BC3 with the support of a NbB2 (0001) surface are expected to replace Pt due to the Gibbs free energy changes extremely close to zero. It is revealed that the catalytic activity of the adsorption site is highly related to the degree of charge transfer between the adsorption site and substrate.

Electrodeposited alloy electrodes in the Co–W–Mo system as highly efficient catalysts for hydrogen production from alkaline water electrolysis

In the presented paper the non-precious electrode materials containing Co, Mo, and W demonstrating high catalytic activity towards hydrogen evolution reaction were characterized. The studied alloy electrodes were electrodeposited from electrolytes with a simple composition, containing CoSO4, Na2WO4, Na2MoO4, and Na3C6H5O7. The structure, surface morphology, and composition of the prepared deposits were analyzed using scanning microscopy, X-ray diffraction, and transmission electron microscopy techniques. Cathodic polarization and electrochemical impedance spectroscopy were applied to assess the electrocatalytic activity and elucidate the HER mechanism in 1 M KOH solution. The nanocrystalline structure, fine grain size, and presence of microcracks on the surface of the studied alloys contributed to their notably high electrochemically active surface area (ECSA) (65.7e2, 11.7e4, and 99.7e3 cm2 for the Co–W, Co–Mo, and Co–W–Mo, respectively), a crucial factor driving their superior catalytic activity. The intrinsic catalytic activity evaluated at the overpotential of 150 mV was 9.2, 3.3, 0.78 and 1.4 μA cm-2 for the Co, Co–W, Co–Mo and Co–W–Mo electrodes, respectively. This indicates that the superior electrocatalytic characteristics observed for the alloy coatings, compared to Co resulted from the substantial increase in their ECSA. Among the investigated electrodes, the ternary Co–W–Mo alloy was characterized by the highest electrocatalytic performance confirmed by the lowest overpotential (42 mV) required to attain a current density of 10 mA cm−2.

Cellulose nanocrystals supported ternary alloy nanoclusters catalysts for efficient hydrogen production from formic acid

Formic acid has gained a lot of attention as one of the most promising liquid hydrogen storage carriers. Designing efficient and cost-effective heterogeneous catalysts for formic acid dehydrogenation can effectively address the challenges of in-situ hydrogen production, storage and transportation. In this study, the Au0.4Pd0.6Pt0.2 alloys with an ultrafine size (∼2nm) were prepared on amino-modified cellulose nanocrystals (CNC) with a total metal consumption of only 0.01mmol. The interaction between the support and nanoclusters provided the stable local environment for the catalysts, which showed remarkable HCOOH catalytic performance at low metal dosage, with TOFinitial of is 4478 h−1 and an Ea of 54.06kJ mol−1 at 323K, and the selectivity of hydrogen is 100%. Density functional theory (DFT) calculations demonstrated that the optimized local electron environment facilitated the OH bond cleavage and reduced the binding energy barrier between H*. This finding is beneficial to the development of more effective catalysts in the future.

Atomically dispersed Mn enhanced catalytic performance for overall water splitting on graphdiyne–coated copper hydroxide nanowire

Atomic catalysts (ACs) have been considered as promising catalysts for efficient hydrogen production through water splitting. Herein, we report an AC with single Mn atoms highly dispersed on the surface of graphdiyne–coated copper hydroxide nanowire arrays (Mn–GDY/Cu(OH)x NWs). By anchoring of Mn atoms on GDY, the specific surface area, the number of active sites, and the stability of the catalyst are greatly improved. Detailed characterizations reveal that the high hydrogen and oxygen evolution reaction (HER/OER) catalytic activity of the catalyst is induced by the strong incomplete charge transfer effect between the metal atoms and the GDY. These advantages enable the electrocatalysts can drive a current density of 10 ​mA ​cm−2 ​at low overpotentials of 188 ​mV and 130 ​mV for OER and HER, respectively, together with excellent long–term stability. Remarkably, the alkaline electrolyzer using Mn–GDY/Cu(OH)x as both cathode and anode electrodes can reach 10 ​mA ​cm−2 only at a much low cell voltage of 1.50 ​V.

Hexagonal Defect‐Rich MnOx/RuO2 with Abundant Heterointerface to Modulate Electronic Structure for Acidic Oxygen Evolution Reaction

AbstractDeveloping green hydrogen energy to power future societies has driven the progress of proton‐exchange membrane water electrolyzers (PEMWE). However, due to the complex anode oxygen evolution reaction (OER) electron transfer process and the strong acidic environment, the most effective catalysts are still Ir‐based nanomaterials. Therefore, exploiting low cost acidic OER catalysts to meet the needs of PEMWE remains a challenging and rewarding task. Herein, hexagonal‐shaped and defect‐rich MnOx/RuO2 heterojunction nanosheets (H/d‐MnOx/RuO2) is designed. The oxygen vacancies and heterogeneous structure enable the H/d‐MnOx/RuO2 catalyst to reach 10 mA cm−2 with only overpotential 178 mV in 0.5 m H2SO4. Density functional theory shows that the oxygen vacancies and heterogeneous interface facilitates the reduction of the adsorption energy of *OOH and the reduction of the energy level of Ru‐Oads, thus suppressing the involvement of lattice oxygen and enhancing the durability. This study provides an effective way to design efficient catalysts for hydrogen production in PEMWE.

Synergistic Promotion of Large-Current Water Splitting through Interfacial Engineering of Hierarchically Structured CoP-FeP Nanosheets with Rich P Vacancies.

The development of hydrogen evolution reaction (HER) catalysts with high performance under large current density is still a challenge. Introducing P vacancies in heterostructure is an appealing strategy to enhance HER kinetics. This study investigates a CoP-FeP heterostructure catalyst with abundant P vacancies (Vp-CoP-FeP/NF) on nickel foam (NF), which was prepared using dipping and phosphating treatment. The optimized Vp-CoP-FeP catalyst exerted prominent HER catalytic capability, requiring an ultra-low overpotential (58 mV @ 10 mA cm-2 ) and displaying robust durability (50 h @ 200 mA cm-2 ) in 1.0 M KOH solution. Furthermore, the catalyst demonstrated superior overall water splitting activity as cathode, demanding only cell voltage of 1.76 V at 200 mA cm-2 , outperforming Pt/C/NF(-) || RuO2 /NF(+) . The catalyst's outstanding performance can be attributed to the hierarchical structure of porous nanosheets, abundant P vacancies, and synergistic effect between CoP and FeP components, which promote water dissociation and H* adsorption and desorption, thereby synergically accelerating HER kinetics and enhancing HER activity. This study demonstrates the potential of HER catalysts with phosphorus-rich vacancies that can work under industrial-scale current density, highlighting the importance of developing durable and efficient catalysts for hydrogen production.

Zinc Nanocomposite Supported Chitosan for Nitrite Sensing and Hydrogen Evolution Applications.

Nanoparticles of ZnO-Chitosan (Zn-Chit) composite were prepared using precipitation methods. Several analytical techniques, such as scanning electron microscope (SEM), transmitted electron microscope (TEM), powder X-ray diffraction (XRD), infrared spectroscopy (IR), and thermal analysis, were used to characterize the prepared composite. The activity of the modified composite was investigated for nitrite sensing and hydrogen production applications using various electrochemical techniques. A comparative study was performed for pristine ZnO and ZnO loaded on chitosan. The modified Zn-Chit has a linear range of detection 1-150 µM and a limit of detection (LOD) = 0.402 µM (response time ~3 s). The activity of the modified electrode was investigated in a real sample (milk). Furthermore, the anti-interference capability of the surface was utilized in the presence of several inorganic salts and organic additives. Additionally, Zn-Chit composite was employed as an efficient catalyst for hydrogen production in an acidic medium. Thus, the electrode showed long-term stability toward fuel production and enhanced energy security. The electrode reached a current density of 50 mA cm-2 at an overpotential equal to -0.31 and -0.2 V (vs. RHE) for GC/ZnO and GC/Zn-Chit, respectively. Electrode durability was studied for long-time constant potential chronoamperometry for 5 h. The electrodes lost 8% and 9% of the initial current for GC/ZnO and GC/Zn-Chit, respectively.

Polarization Reorientation of Carbon Nitride Induced by a Local Bridge Donor for Boosting Photocatalytic H2 Evolution Integrated with Selective Amine Oxidation

Polymeric carbon nitride (PCN) has attracted much attention in the field of photocatalysis, but the use of PCN is often confined to internal structures with highly symmetrical heptazine units bridged by N atoms. Accurate tuning of the positions of heteronuclear atoms is a meaningful strategy but remains a big challenge. Herein, a catalyst with P═N bonds accurately embedded among the heptazine units was prepared using a straightforward polymerization method. According to density functional theory simulation and experimental data, the embedded P═N chains act as donor units that cause a profound redistribution of the symmetric electron cloud density of heptazine, which significantly promotes local charge polarization and leads to a strong built-in electric field. The consequence is enhanced exciton dissociation, charge separation, and surface activation. In the photocatalytic oxidation of benzylamine over the optimized PCN under visible light irradiation without the use of a solvent and co-catalyst, the hydrogen production rate is 388 μmol·g–1·h–1 and the selectivity to N-benzylidenebenzylamine is >99%. In this paper, we propose a tractable strategy to precisely tune the position of heteroatoms, providing an efficient catalyst for hydrogen production together with the simultaneous generation of value-added imines.

Covalent Triazine Framework Encapsulated Ultrafine PdAu Alloy Nanoclusters as Additive-Free Catalysts for Efficient Hydrogen Production from Formic Acid

Dehydrogenation of formic acid (FA) represents a promising route for clean hydrogen production, the economic viability of which, however, is largely hindered by the catalyst inefficiency. Here, ultrafine Au–Pd bimetallic nanoclusters (NCs) confined within the cavities of bipyridyl covalent triazine frameworks (CTFs) are constructed via a metal-nitrogen coordination reduction strategy, which is enabled by the chelation between bidentate nitrogen sites of the bipyridine ligands and metal ion precursors. The resulting CTF-confined PdAu NCs exhibit a high initial turnover frequency up to 12,368 h–1 (333 K) toward the dehydrogenation of FA without any additives. The experimental and theoretical studies disclose that the pyridinic nitrogen sites of CTF not only facilitate the formation of monodisperse small-sized metal NCs via the anchoring and the pore confinement effect but also serve as a proton buffer which can store excess protons and thus suppress the recombination of adsorbed formate and hydrogen on the PdAu alloy surface. These findings would have significant implications for designing high-performance hydrogen production catalysts.

Bimetal‐Incorporated Black Phosphorene with Surface Electron Deficiency for Efficient Anti‐Reconstruction Water Electrolysis

AbstractSurface reconstruction (SRC) is a common phenomenon and a promotion manner for Ni/Co‐based precatalysts during the water splitting process. However, the catalytic surface reconstruction will in turn complicate the streamlined prediction and modeling on the catalytic activity. Hence, the rational design of anti‐SRC catalysts is highly desirable, but challengeable. In this article, a series of affordable bimetal‐incorporated black phosphorene (BP) catalysts are constructed by an in situ electro‐exfoliation/insertion method for anti‐SRC water electrolysis. It is found that the bimetals (e.g., NiFe, NiPd) are of cationic and covalent incorporation with electron‐deficient state in few‐layer BP. The optimized bimetal‐BP structures present excellent and stable catalytic performances with low overpotentials in hydrogen evolution (HER, 53 mV, NiPd‐BP) and oxygen evolution (OER, 268 mV, NiFe‐BP) reactions at 10 mA cm−2 in 1 m KOH. The anti‐SRC behaviors are elucidated by in situ Raman studies during HER/OER, probably due to the balanced electron transfer pathway on Ni sites. This research opens interesting possibilities for designing the anti‐SRC catalysts for efficient hydrogen production and authentic structure‐activity understandings.

Synergistic Coupling of Hierarchical Heterostructured Ni3P/Ni/VN Microflower Electrocatalyst for Enhanced Hydrogen Evolution Reaction

AbstractThe exploration of economical and highly efficient electrocatalysts for hydrogen evolution reaction (HER) is paramount for the development of sustainable hydrogen economy. Herein, a novel three‐dimensional (3D) hierarchical microflower electrocatalyst comprised of N‐doped carbon‐armored Ni3P/Ni/VN heterogeneous nanoparticles (Ni3P/Ni/VN@NC) is developed by combining a hydrothermal method with in‐situ carbonization‐phosphating strategy. The unique robust hierarchical structure derived from 3D NiV layered double hydroxide (NiV‐LDH) skeleton as precursor provides multidimensional mass and charge transport channels as well as numerous active sites for HER, leading to the improved HER activity. More importantly, the possible electron transfer route of Ni3P→Ni→VN is demonstrated due to the charge pumping capability of VN during interfacial electron intercoupling among the tri‐component, which endows Ni3P/Ni/VN with the favorable absorption of hydrogen‐intermediates and thus upgraded HER kinetics over such heterostructure. The resulting Ni3P/Ni/VN@NC catalyst exhibits extremely low overpotentials of 81 mV and 134 mV to deliver a current density of 10 mA cm−2 without iR‐compensation in alkaline and acidic media, respectively, and maintains continuous operation for over 90 h. This work enlightens the rational design of hierarchical multi‐component heterostructured catalysts for efficient hydrogen production.

Aluminum nanotubes as an efficient catalyst for hydrogen production via thermochemical water splitting: a reactive molecular dynamics simulation.

Water splitting is the process of using energy to break down water molecules into hydrogen and oxygen. The use of an aluminum catalyst in the thermochemical process can help to increase the efficiency and rate of the reaction. Furthermore, aluminum is a relatively inexpensive material that can be easily produced, making it an appealing option for use in large-scale water-splitting operations. We investigated the reaction mechanism between aluminum nanotubes and water at various temperatures using reactive molecular dynamic simulations. We found that an aluminum catalyst makes it possible to split water at temperatures higher than T > 600 K. It was also observed that the yield of H2 evolution is dependent on the diameter of the Al nanotube and decreases with increasing size. During the process of splitting water, the inner surfaces of the aluminum nanotubes are seen to be severely eroded, as shown by changes in the aspect ratio and solvent-accessible surface area. In order to compare the H2 evolution efficiency of water with other solvents, we also split a variety of solvents, including methanol, ethanol, and formic acid. We presume that our study will give researchers enough knowledge to create hydrogen through thermochemical process in the presence of an aluminum catalyst by dissociating water and other solvent molecules.

Uniform dispersion of ultrafine ruthenium nanoparticles on nano-cube ceria as efficient catalysts for hydrogen production from ammonia-borane hydrolysis

Ultrafine Ru nanoparticles supported on nano-cube ceria with Ce3+ and oxygen vacancies can provide a strong metal–support interaction, thereby exhibiting superior catalytic performance toward AB hydrolysis.

Metal based catalysts for hydrogen production reactions

Hydrogen is an outstanding source of energy and plays very important part in energy system. Hydrogen is one of the best energy carrier alternatives to fossil fuels because of its high energy density. It is very important to produce clean and renewable energy sources due to increasing population and pollution day by day. In 2018, the maximum hydrogen (94%) is manufactured from fossil fuels by steam reforming of natural gas, partial oxidation of the methane gas as well as coal gasification. The hydrogen production plays important role in any industrialized society, since hydrogen is required for many essential chemical processes. Several designed metal-based ideas can be employed as an efficient catalyst for hydrogen production for the alternate source of energy and society benefits. Proposed review is highlighting the different efficient strategies for hydrogen production.

Au@Cu2O core@shell nanocrystals as sustainable catalysts for efficient hydrogen production from ammonia borane

The use of Au@Cu2O core@shell nanocrystals as sustainable catalysts for efficient hydrogen (H2) production from ammonia borane (AB) is demonstrated. By combining the attributes associated with core@shell structural features and electronic interactions, Au@Cu2O exhibited remarkable performance toward AB hydrolysis. The effect of shell thickness on H2 production performance was systematically investigated. Results showed that H2 production rate increased monotonically with shell thickness, while degree of dehydrogenation of AB was subject to optimization by shell thickness. A maximal 3.0 equivalents of H2 production can be achieved by Au@Cu2O with an optimal Cu2O shell thickness. The H2 produced from AB hydrolysis on Au@Cu2O was introduced to power a fuel cell for lightening light emitting diodes. The findings from the work not only enrich the family of metal/metal oxide composite catalysts for AB hydrolysis, but also deepen the fundamental understanding of implications of core@shell structural features and electronic interactions in dehydrogenation of AB.

Two-dimensional double transition metal carbides as superior bifunctional electrocatalysts for overall water splitting

The development of bifunctional catalysts that can outperform precious metal electrocatalysts for overall water splitting is a critical task for sustainable green hydrogen production. Owing to the rich surface chemistry, unique physiochemical properties, and good stability, MXenes are considered efficient catalysts for hydrogen production. However, it is still a challenge to harmonize both HER (Hydrogen evolution reaction) & OER (Oxygen evolution reaction) reactions in the same media. Herein, we have reported the synthesis of Mo2TiC2Tx and Mo2Ti2C3Tx double transition metal carbides as NMP (non-precious metal) based bifunctional catalysts for overall water splitting in alkaline media. The LSV (linear sweep voltammetry) was employed for investigating catalytic activity, revealing the outstanding performance of Mo2TiC2Tx and Mo2Ti2C3Tx for high HER activity with an overpotential of 34 mV and 51 mV respectively, to reach a benchmark current density of 10 mAcm−2. The Mo2TiC2Tx also exhibited excellent OER activity with an overpotential of 320 mV as compared to 470 mV for Mo2Ti2C3Tx. The overall water splitting test uncovers a cell voltage of 1.57 V for Mo2TiC2Tx \\\\ Mo2TiC2Tx configuration. This study provides a comparison of two double transition MXene systems for effective use as bifunctional catalysts that opens new horizons for their use in clean hydrogen production.

Efficient Cu/CeO2 composites for hydrogen production from photothermal methanol steam reforming: The utility of synergism of photo and thermal catalysis

Exploring efficient catalysts for hydrogen production from methanol steam reforming (MSR) is quite challenge. Introducing a photosensitive material into conventional thermal catalysts is a promising protocol to enhance MSR reactivity. By utilizing the plasmonic effect of copper and the oxygen vacancy on ceria, we developed Cu/CeO2 catalysts for photothermal MSR, by which the synergism of photo and thermal effects greatly improved the activity and stability of Cu/CeO2. The proper Cu nanoparticle size, the highest UV–visual light absorption ability and the strongest Cu-CeO2 interaction in the 10 %-Cu/CeO2 catalyst contributed to the best MSR performance than the 5 %-Cu/CeO2 and 20 %-Cu/CeO2 counterparts, methanol conversion of 95.5 % and H2 yield of 36 mL/(gcatmin) at 250C were obtained under Xenon lamp irradiation. This work demonstrates the effective Cu/CeO2 catalysts in photothermal MSR reaction for hydrogen production, and the findings should aid the understanding on photothermal catalytic mechanism.

Synthesis of novel activated carbon-supported trimetallic Pt–Ru–Ni nanoparticles using wood chips as efficient catalysts for the hydrogen generation from NaBH4 and enhanced photodegradation on methylene blue

A novel activated carbon (AC) supported trimetallic Platinum–Ruthenium–Nickel nanoparticles (AC@Pt–Ru–Ni NPs) synthesized as an efficient catalyst for hydrogen production from NaBH4 and enhanced photodegradation ability on methylene blue (MB) dye is reported. AC, which is used as a support material in nanoparticle synthesis, was produced from wood chips. X-ray diffractometry (XRD), atomic force microscope (AFM), Fourier transform infrared spectrophotometer (FTIR), Transmission Electron Microscope (TEM), and UV–visible spectrophotometer (UV–Vis) are used for nanoparticles characterization. According to XRD analysis, the average crystal particle size was measured to be about 3.44 nm. In TEM analysis, the average particle size was determined as 2.44 nm. The photocatalytic activity of AC@Pt–Ru–Ni NPs was examined against MB azo dye and found to have 97% photocatalytic degradation at 300 min against MB. The catalyst activity of AC@Pt–Ru–Ni NPs in hydrogen production was determined by the methanolysis reaction from NaBH4. The Turnover of Frequency (TOF), Activation energy (Ea), enthalpy (ΔH), and entropy values (ΔS) values of the hydrogen production reaction were calculated as 1154.04 h−1, 24.29 kJ/mol, 26.83 kJ/mol, −198.76 J/mol.K, respectively. The study successfully achieved the recycling of wood waste, production of hydrogen, and photodegradation against MB dye. In this study, wood wastes were evaluated and it was aimed to be used in AC production and nanocatalyst synthesis. The efficiency of the synthesized AC@PtRuNi nanocatalyst in hydrogen production and its usability for cleaning dyes from wastewater was determined. The obtained results show that AC@PtRuNi nanocatalyst has potential usability both in hydrogen production and in applications for cleaning dyes from wastewater.

Silk fibroin derived porous carbon aerogels confined hyperdispersed Rh nanoparticles to achieve electrocatalytic hydrogen evolution under high current density

In order to meet the current demand for clean energy and realize industrial application, it is urgent to develop highly efficient catalysts for hydrogen production from electrolytic water. Herein, we successfully synthesize hyperdispersed Rh nanoparticles on silk fibroin derived porous N-doped carbon aerogels (N-Rh/CA) using environment friendly silk fibroin as precursor material. The bonding between Rh and N anchored Rh nanoparticles uniformly super-dispersed on the substrate, exposing plentiful active sites. This N-Rh/CA with ultra-low metal content (2 wt %) exhibits the Pt-like electrocatalytic activity for hydrogen evolution, delivering current density of 10 and 100 mA cm−2 at a ultrasmall overpotential of 65 mV and 210 mV, respectively. Meanwhile, N-Rh/CA possesses a mass activity of 196.81 A g−1 at potential of 150 mV, and exhibits outstanding economic efficiency compared with Pt/C and reported Rh-based electrocatalyst. Furthermore, the electrocatalyst showed superior stability for the hydrogen evolution reaction, paving way for its potential industrial application.