Hydrogen Generation Rate Research Articles

An overview of hydrogen generation by hydrolysis of Al and its alloys with the addition of carbon-based materials

Al and its alloys are studied extensively for hydrogen generation through water splitting. Alloying Al with metal activators such as bismuth, indium, gallium, etc., leads to the formation of micro galvanic cells during hydrolysis reaction, resulting in an improved hydrogen generation rate. Activation of Al by adding carbon-based materials such as graphite, carbon nanotubes (CNTs), graphene, etc., can instantaneously generate hydrogen at room temperature. When carbon particles are desorbed from the Al matrix during hydrolysis, new Al is exposed, resulting in an increased reaction rate. In Al-Graphite composites which form core-shell structures, H2O molecules penetrate through the graphite layers and break down the core-shell structure during hydrolysis, and the new Al surfaces are exposed to water. It was found that Al with nano bismuth and graphene nanosheets showed better hydrogen generation rate and hydrogen yield. Graphene nanosheets control the agglomeration of Al and enhance the specific surface area for hydrolysis. During the hydrolysis of Al-CNTs composites, CNTs act as a cathode, resulting in galvanic corrosion between CNTs and the Al matrix. CNTs can also effectively control the agglomeration of Al during ball milling. Spark plasma sintered Al–Bi-CNT composites showed an enhanced hydrogen generation rate during hydrolysis. This paper presents an overview of hydrogen generation by hydrolysis of Al and its alloys, emphasising the addition of carbon-based materials such as graphite, graphene, CNTs, etc.

Bifunctional Ru-Cluster-Decorated Co3 B-Co(OH)2 Hybrid Catalyst Synergistically Promotes NaBH4 Hydrolysis and Water Splitting.

Developing a highly efficient bifunctional catalyst for hydrolysis of metal hydrides and spontaneous hydrogen evolution reaction (HER) is essential for substituting conventional fuels for H2 production. Herein, Ru-cluster-modified Co3 B-Co(OH)2 supported on nickel foam (Ru/Co3 B-Co(OH)2 @NF) is constructed by electroless deposition, calcination and chemical reduction. The catalyst exhibits an excellent hydrogen generation rate (HGR) of 4989 mL min-1 and good reusability, superior to most previously reported catalysts. Besides, Ru/Co3 B-Co(OH)2 @NF displays a prominent hydrogen evolution reaction catalytic capability with a low overpotential of 153.0 mV at 100 mA cm-2 (50.5 mV at 10 mA cm-2 ), a small Tafel slope of 40.0 mV dec-1 and long-term stability (100 h@10 mA cm-2 ) in 1.0 M KOH. The excellent catalytic H2 generation capacity benefits from the rapid charge transfer promoted by metallic Co3 B, the synergistic catalytic effect of Co3 B-Co(OH)2 and Ru clusters, and the unique composite structure favorable for solute transport and gas emission.

Highly active and stable CuAlOx/WO3 photoanode for simultaneous pollutant degradation, hydrogen and electricity generation

An unassisted solar water-energy nexus system (SWENS) based on an ultra-thin CuAlOx overlayer coated WO3 nanoplate array (CuAlOx/WO3) photoanode, a rear silicon solar cell and a Pt-black/Pt cathode was proposed to efficiently degrade refractory organic pollutants and simultaneously produce hydrogen and electricity. The formed p-n junction between p-type CuAlOx and n-type WO3 effectively facilitated the charge separation in the CuAlOx/WO3 photoanode. Moreover, the CuAlOx overlayer enhanced the capture of photogenerated holes and isolated WO3 from the solution, thereby improving the charge transfer and inhibiting the photocorrosion of WO3. Therefore, the optimized CuAlOx/WO3 photoanode showed a significantly enhanced and stable photocurrent density of ∼2.82 mA cm−2 at 1.0 V vs. Ag/AgCl, which was ∼4 times higher than that of the pristine WO3. Based on this outstanding photoelectrocatalytic performance, the assembled SWENS showed a degradation efficiency of nearly 100% for tetracycline, a hydrogen generation rate of ∼26.8 μmol·h−1·cm−2 and a power density of ∼593 μW cm−2 under simulated solar light illumination. Our SWENS also exhibited outstanding universality in degrading various refractory organic pollutants for green energy production.

Metal-free hybrid composite particles with phosphorus and oxygen-doped graphitic carbon nitride dispersed on kaolin for catalytic activity toward efficient hydrogen release

Here, hybrid kaolin-g-C3N4 heterostructure particles were fabricated by calcination in the first step, followed by hydrothermal phosphoric acid activation in the second step, and phosphorus (P) and oxygen (O) doped kaolin-g-C3N4 metal-free catalyst was synthesized. This hybrid metal-free catalyst was used for the first time for the production of effective hydrogen (H2) from sodium borohydride (NaBH4) methanolysis. The hydrogen generation rate (HGR) value of 5500 ml min−1g−1 was obtained with the P and O doped kaolin-g-C3N4 catalyst. The activation energy (Ea) of 31.90 kJ mol−1 by P and O doped kaolin-g-C3N4 for the production of H2 was obtained. The kaolin-g-C3N4 and P and O doped kaolin-g-C3N4 metal-free catalysts were systematically characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). Based on the results obtained, the mechanism of P and O-doped kaolin-g-C3N4 catalyst on H2 production from NaBH4 methanolysis was also proposed.

An all-organic S-scheme heterojunction containing donor–acceptor type conjugated polymer and C3N4 nanosheets assembled via π–π interaction for photocatalytic H2 generation

Designing an excellent photocatalyst with high space separation efficiency of photogenerated carriers to boost the rate of photocatalytic hydrogen (H2) generation remains a challenge. In this work, the S-scheme heterojunction containing a donor–acceptor (D-A) type conjugated polymer of PyDTDO-3 and a two-dimensional (2D)-layered conjugated polymer of C3N4 nanosheets with conjugated heptazine units (denoted as PCNNS) was prepared for photocatalytic H2 production. It is found that the recombination rate of photogenerated electron-hole pairs is decreased by the S-scheme heterojunction structure through establishing an intimate π–π conjugated heterointerface between PyDTDO-3 and C3N4 NS. To clarify the potential photocatalytic mechanism, diversified characterization techniques were employed and the density functional theory (DFT) calculations were conducted. As a result of the difference in the work function, a Fermi level gap is formed between PyDTDO-3 and C3N4, which eventually leads to the band edge bent upward/downward and the presence of the built-in electric field causing the spontaneous interfacial charge transfer from C3N4 NS to PyDTDO-3 at the π–π conjugated interface. Owing to its unique structure and optical properties, the optimal P2CNNS heterojunction photocatalyst shows excellent photocatalytic H2 generation performance, which reaches a maximum of 50.2 mmol g−1 h−1 under visible illumination.

Microwave-accelerated hydrolysis for hydrogen production over a cobalt-loaded multi-walled carbon nanotube-magnetite composite catalyst

Microwave (MW) irradiation is a promising option for the intensification of chemical reaction processes and has been applied in the promotion of many catalytic reactions. Herein, the (CNTs-Fe3O4)-Co nanocomposites were designed as microwave-responsive catalysts and was fabricated under a controlled manner. The experimental results showed that MW irradiation can lead to the hydrogen generation rate (HGR) of the (CNTs-Fe3O4)(1:4)-Co (10 wt%) catalyst being boosted from 75.0 to 95.4% as compared with conventional heating under the temperature range of 40 to 60℃. Moreover, the evaluation of the catalytic performance of the (CNTs-Fe3O4)(1:4) composite with different Co loadings and DFT calculations were carried out to verify the synergistic effect of cobalt and Fe3O4 sites of the (CNTs-Fe3O4)(1:4)-Co (10 wt%) catalyst. Furthermore, the pre-exponential factor (A) of NaBH4 hydrolysis under MW heating was found to be approximately 15 times higher than that of conventional heating, implying that MW irradiation significantly improved the effective collision frequency of the atoms at the reaction interface of the catalyst, resulting in a higher number of active sites on the surface of the (CNTs-Fe3O4)(1:4)-Co (10 wt%) catalyst. Additionally, the existence of the non-thermal effect of MW irradiation was studied by using a specially designed experimental set-up. The results showed that MW thermal and non-thermal effects contributed to the enhancement of HGR.

Hydrogen generation from NaBH4 hydrolysis catalyzed by cobalt (0)-Deposited cross-linked polymer brushes: Optimization with an experimental design approach

Proposing a novel catalyst that achieves catalytic hydrolysis of metal hydrides is an important stage in developing a hydrogen storage system. In this study, a cross-linked gel brush-cobalt (0) composite (Co@P4VPGB@PMC) has been synthesized to obtain hydrogen from NaBH4 solution. The morphology, structure, and composition of the obtained catalyst have been characterized by, FTIR, SEM, EDX, BET, XRD, ICP-MS and XPS. The parameters that significantly affect the hydrolysis of NaBH4 (such as NaBH4 concentration, NaOH amount, catalyst amount, and temperature) have been investigated using response surface methodology (RSM), an optimization method that has gained increasing importance in recent years. The hydrogen generation rate (HGR) was 4499 mL/min gcat for Co@P4VPGB@PMC when the NaBH4 amount was 241.52 mM, NaOH amount 5 wt%, catalyst amount 10.55 mg and temperature 58.9 °C. Moreover, the apparent activation energy (Ea) for the catalytic hydrolysis reaction has been 41.27 kJmol-1 obtained under optimum conditions. Additionally, the Co@P4VPGB@PMC catalyst displayed significant reusability performance for up to five cycles without major loss of its activity. Compared with metal catalysts, this new cross-linked polymer gel brush-cobalt catalyst has excellent potential applications for hydrogen production by hydrolysis of metal hydrides due to its simple synthesis, low cost, and the easy availability of raw materials.

2D porphyrin-based MOFs with highly dispersed Pt nanoparticles via in-situ partial reduction strategy from porphyrin embedded with single-atom Pt for enhancing photocatalytic hydrogen production

An efficient and stable 2D MOF TMF-Pt/Pt NPs photocatalyst was prepared by in-situ partial hydrogenation reduction of TMF-Pt with single-atom Pt embedded in porphyrin center to improve photocatalytic hydrogen production. It is important to note that TMF-Pt/Pt NPs has an extremely high photocatalytic hydrogen generation rate (33185.66 µmol·g−1·h−1) in comparison to the majority of previous MOFs photocatalysts, which could be due to the in-situ uniformly grown Pt NPs are very adjacent to the Ti-oxo clusters within the 2D MOFs so that the gradually accumulated electrons around the Ti-oxo clusters via LMCT pathway could instantaneously transfer to Pt NPs through the Schottky injection field effect. Through a series of experimental characterizations, especially atomic force microscopy (AFM) and transmission scanning electron microscope (TEM), confirmed the highly dispersed Pt NPs within the 2D MOFs. This work provided us with a novel idea to realize the uniform distribution of noble metals nanoparticles in the channel cavity of MOFs through an in-situ synthesis strategy, so as to facilitate the more efficient Schottky injection field effect between noble metals nanoparticles and metal clusters of the MOFs, thereby achieving more excellent charge carrier separation efficiency.

A comparison study on methanol reforming catalysts for onboard hydrogen generation

In hydrogen energy applications, methanol is the best fuel that can effectively solve the problem of the storage and transportation of hydrogen. The lowest reforming temperature among hydrocarbons also makes it the best fuel for hydrogen generation. This paper aimed to study and compare four methanolreforming catalysts and screen the best one suitable for the on-board hydrogen generation system. In this study, the in-house single-tube reactor, which can precisely control the temperature by a multistage heater, was applied to study the catalyst performance. Physical and chemical properties of the catalyst, such as methanol conversion rate, hydrogen generation rate, CO selectivity at a different liquid hourly space velocity (LHSV), catalyst density, and optimum reaction temperature, were also systematically studied. The hydrogen generation rate per unit mass of the WEF catalyst is the highest, which reached 0.122 g/h·gcat in 9.23 h-1 LHSV. And the methanol conversion rate in 7.72 h-1 LHSV is 96.74%, and somewhat below the BSF catalyst (97.90% in 7.55 h-1 LHSV). The study indicated that the catalyst made by WEF is the best catalyst for on-board hydrogen generation when comprehensively considering the requirement including the performance and vibration resistance. At the end of this paper, the optimized direction of the four catalyzers is also specified.

Performance study of a new parabolic trough design under optical concentrator effect

• A new hybrid parabolic trough concentrator is proposed. • A new algorithm for the hybrid trough concentrator is presented. • The influence of the optical concentrator on the hybrid system performance is studied. • Results showed a maximum thermal efficiency of 86 % corresponding to 318.9 Watts as additional electrical power while the heat losses are reduced from 2.76% to 1.9%. • The chemical interactions within Therminol VP1 stay stable and the hydrogen production rate remains at 2.90µmol/kg/h, reducing the possibility of cracking problems. The production of thermal and electrical energy by conventional and hybrid parabolic trough concentrators is widely considered most important in the field of renewable systems. In this work, two main problems of parabolic trough concentrators were studied with the aim of minimizing them as much as possible, namely, the cracking of Therminol VP1 and heat loss. The cracking problem of Therminol VP1 is one of the major troubles of parabolic trough systems at high temperatures (400°C) due to its dramatic consequences, which decrease significantly the thermal and electrical efficiency of parabolic trough concentrator. To address these issues, the temperature of Therminol VP1 was automatically controlled by a new parabolic trough concentrator integrated with two different types of tubular thermoelectric generators. A new mathematical model was offered for this hybrid system. In addition, a set of thirteen non-linear equations were discretized using the finite difference method. The discretized equations were coded in MATLAB (2015a) software based on the Gauss-Seidel technique with an accuracy of 0.001. To confirm the predicted results of the new numerical model, a literature paper was used for comparison. The comparison between the predicted and literature results was in good agreement. The effect of solar concentrator ratio on the thermal and electrical performance of the new system was analyzed and discussed. The major results show that the maximum thermal efficiency of the new system up to 86 % corresponding to 318.9 Watts of additional electrical power. Also, the maximum storage of hot water at 95 °C and Therminol VP1 at 400 °C up to 251.5 Liter/Day and 383.8 Liter/Day, respectively. Additionally, the cracking problem of Therminol VP1 was effectively controlled. More precisely, the hydrogen generation rate was automatically stabilized at a low and stable value of 2.90 µmol/kg/h. In addition, the heat losses rate was reduced from 2.97% to 1.07% with increasing solar concentration ratio. These results represent a useful reference for the selection of this new hybrid parabolic trough concentrator in view of its developed and intelligent performance.

A novel molecularly expanded covalent triazine framework heterojunction with significantly enhanced molecular oxygen activation and photocatalysis performance under visible light.

The activation capacity of molecular oxygen is an important indicator to evaluate the photocatalytic efficiency of photocatalysts. In this paper, WS2 nanosheet was deposited on hyper-crosslinked CTF-1-G (obtained by molecular expansion from covalent triazine framework CTF-1) to form a C-GW heterojunction, which promoted the photodegradation of pollutants and the activation of molecular oxygen. This novel C-GW heterojunction exhibited excellent degradation property for organic pollutants (tetracycline (TC), rhodamine B (RhB)) and activating molecular oxygen under visible light irradiation. Among them, C-GW15 could degrade 98% of 20 ppm TC in 60 min and 99% of 30 ppm RhB in 30 min, and it had the highest hydrogen generation rate and hydrogen production amount in 4 hours, which were 8.74 mmol h-1 g-1 and 34.94 mmol g-1, respectively. Meanwhile, C-GW15 had the strongest 3,3',5,5'-tetramethylbenzidine oxidation capacity and could generate 1.83 μmol of ˙O2- in 60 min and the production of H2O2 was 20.8 μmol L-1 in 40 min. The results of this study clearly indicated that the combination of WS2 and CTF-1-G can enhance the visible light absorption capacity and photogenerated carrier separation efficiency, thus promoting the photocatalytic performance. Finally, a Z-type photocatalytic mechanism was proposed based on radical capture, molecular oxygen activation experiments and electron spin resonance analysis. These findings will extend the fundamental understanding of the Z-type photocatalytic mechanism and provide new opportunities for the rational design of CTF heterojunctions for the treatment of environmental pollution and clean energy conversion.

Facial synthesis of FeS2@Carbon nanotube composite as an efficient electrocatalyst for hydrogen evolution reaction

Iron disulfide (FeS2) has attracted extensive research interest due to its excellent catalytic efficiency. In this work, FeS2 was composited with carbon matrix to prepare a highly efficient electrocatalyst for hydrogen evolution. Two uniformly composites, namely, FeS2 @carbon nanotube (FeS2@CNT) and FeS2@carbon particle (FeS2@CP), were successfully prepared by pyrolysis and sulfuration processes. The structures of the synthesized composites were characterized by powder X-ray diffraction (PXRD), scanning electron microscope, transmission electron microscope, and X-ray photoelectron spectroscopy. It was found that the catalytic performances of the composites were obviously improved compared to pure FeS2. Moreover, compared to FeS2@CP, the FeS2@CNT nanotubes achieved a much lower overpotential and a smaller Tafel slope. The enhanced HER kinetics and hydrogen generation rate of FeS2@CNT may be due to its more efficient charge transport, uniform distribution of active sites, and higher surface areas. This work provides a new clue for the preparation of FeS2-based composite for hydrogen evolution.

Controlled Ni doping on a g-C3N4/CuWO4 photocatalyst for improved hydrogen evolution.

The development of a low-cost, environment-friendly and suitable semiconductor-based heterogeneous photocatalyst poses a great challenge towards extremely competent and substantial hydrogen evolution. A series of environment-friendly and proficient S-scheme Ni-doped CuWO4 nanocrystals supported on g-C3N4 nanocomposites (Ni-CuWO4/g-C3N4) were constructed to ameliorate the photocatalytic efficacy of pure g-C3N4 and Ni-CuWO4 and their activity in H2 generation through photocatalytic water splitting was evaluated. The Ni-CuWO4 nanoparticles were synthesized through doping of Ni2+ on wolframite CuWO4 crystals via the chemical precipitation method. An elevated hydrogen generation rate of 1980 μmol h-1 g-1 was accomplished over the 0.2Ni-CuWO4/g-C3N4 (0.2NCWCN) nanocomposite with an apparent quantum yield (AQY) of 6.49% upon visible light illumination (λ ≥ 420 nm), which is evidently 7.1 and 17.2 fold higher than those produced from pristine g-C3N4 and Ni-CuWO4. The substantial enhancement in the photocatalytic behaviour is primarily because of the large surface area, limited band gap energy of the semiconductor composite and magnified light harvesting capability towards visible light through the inclusion of g-C3N4, thus diminishing the reassembly rate of photoinduced excitons. Further, density functional theory (DFT) calculations were performed to investigate the structural, electronic and optical properties of the composite. Theoretical results confirmed that the Ni-CuWO4/g-C3N4 composite is a potential candidate for visible-light-driven photocatalysts and corroborated with the experimental findings. This research provides a meaningful and appealing perspective on developing cost-effective and very proficient two-dimensional (2D) g-C3N4-based materials for photocatalytic H2 production to accelerate the separation and transmission process of radiative charge carriers.

Dual roles of sub-nanometer NiO in alkaline hydrogen evolution reaction: breaking the Volmer limitation and optimizing d-orbital electronic configuration.

Pt-based nanoclusters toward the hydrogen evolution reaction (HER) remain the most promising electrocatalysts. However, the sluggish alkaline Volmer-step kinetics and the high-cost have hampered progress in developing high-performance HER catalysts. Herein, we propose to construct sub-nanometer NiO to tune the d-orbital electronic structure of nanocluster-level Pt for breaking the Volmer-step limitation and reducing the Pt-loading. Theoretical simulations firstly suggest that electron transfer from NiO to Pt nanoclusters could downshift the Ed-band of Pt and result in the well-optimized adsorption/desorption strength of the hydrogen intermediate (H*), therefore accelerating the hydrogen generation rate. NiO and Pt nanoclusters confined into the inherent pores of N-doped carbon derived from ZIF-8 (Pt/NiO/NPC) were designed to realize the structure of computational prediction and boost the alkaline hydrogen evolution. The optimal 1.5%Pt/NiO/NPC exhibited an excellent HER performance and stability with a low Tafel slope (only 22.5 mv dec-1) and an overpotential of 25.2 mV at 10 mA cm-2. Importantly, the 1.5%Pt/NiO/NPC possesses a mass activity of 17.37 A mg-1 at the overpotential of 20 mV, over 54 times higher than the benchmark 20 wt% Pt/C. Furthermore, DFT calculations illustrate that the Volmer-step could be accelerated owing to the high OH- attraction of NiO nanoclusters, leading to the Pt nanoclusters exhibiting a balance of H* adsorption and desorption (ΔGH* = -0.082 eV). Our findings provide new insights into breaking the water dissociation limit of Pt-based catalysts by coupling with a metal oxide.

Co@ZIF‐8/TiO2 heterojunction for green hydrogen generation

A wet‐incipient impregnation method was reported to synthesize hierarchical porous bimetallic (Co, Zn)‐zeolitic imidazolate frameworks (ZIF‐8)/TiO2 (Co@ZIF‐8/TiO2) for green hydrogen generation via photocatalytic water splitting. Co@ZIF‐8/TiO2 showed higher photocatalytic efficiency than TiO2, with a hydrogen generation rate (HGR) of 13 mmol·h−1·g−1 with a 151‐fold increase in the catalytic performance of TiO2. The photocatalytic HGR of Co@ZIF‐8/TiO2 was superior to that of the ZIF‐8/TiO2 heterostructure. Co@ZIF‐8 showed a hierarchical porous structure containing micropores and mesopores regimes, providing a proficient transport channel for charge transfer. This study presents new prospects for using hierarchical porous metal–organic frameworks (MOFs) as support and promoter in photocatalytic applications of semiconductor such as TiO2.

Hydrogen generation and stoichiometric hydrolysis of core–shell Al-Li-NaBH4 composite

Hydrogen energy has attracted considerable attention as a promising alternative to petroleum. Herein, a novel (Al–x%Li)–y%NaBH4 composite with a core–shell structure has been designed and synthesized by a one-step ball-milling method for generating hydrogen by hydrolysis. NaBH4 formed a surface coating that completely wrapped the Al–x%Li alloy particles to prevent agglomeration and oxidation. Meanwhile, the synergism between the Al–Li alloy and NaBH4 promoted the hydrogen generation rate (HGR) of the composite. The total hydrogen release content of (Al–10%Li)–10%NaBH4 reached 1468.8 mL·g−1, with the highest HGR reaching 4393.7 mL·g−1·min−1 at 303 K. The (Al–x%Li)-y%NaBH4 composites also exhibited outstanding hydrolysis capacity during reaction with a near-stoichiometric amount of added CoCl2 solution. The hydrogen emission exceeded 90% when only twice the amount of stoichiometric CoCl2 solution was injected. The hydrogen mass density of the total system increased to more than 2.3 wt% from approximately 0.6 wt% with the addition of 10 stoichiometric solution, indicating the practical application of the portable fuel cell in conserving the total volume of the facility.

Facile one pot synthesis of nitrogen doped reduced graphene oxide supported Co3O4 nanoparticles as bifunctional catalysts for the reduction of 4-nitrophenol and NaBH4 hydrolysis

The development of catalyst materials with significant potential and multifunctional applicability is essential for sustainable energy and environmental applications. The present work reports the preparation of nitrogen doped reduced graphene oxide supported Co3O4 nanoparticles (NGCO) via a simple and cost effective one pot synthesis method, at a relatively low temperature. The prepared NGCO composites were employed for the first time as active bifunctional catalysts in the reduction of 4-nitrophenol (4NP) and NaBH4 hydrolysis. The NGCO catalyst exhibited excellent catalytic activity and stability for the 4NP conversion with a mass normalized rate constant of 97.8 min−1g−1 at 303 K. The concentration (0.7 mM) and volume (20 mL) of the 4NP solution used in this study was higher than most of the works in the literature and that signifies the novelty of the prepared NGCO catalyst materials. The NGCO catalysts also showed potential activity and durability in liberating hydrogen from NaBH4, via hydrolysis, with a maximum specific hydrogen generation rate of 2090.6 mL min−1 gCo−1. The kinetics of the catalytic NaBH4 hydrolysis reaction was investigated using zero order and first order kinetic models. The experimental data was well-described with the zero-order kinetic model. The improved catalytic activity of the NGCO composites relative to the unsupported Co3O4 nanoparticles is due to the excellent dispersibility of the active sites and the synergetic action of both Co3O4 and N doped graphene support in NGCO.

Decorating ZnS by ZnIn2S4 to fabricate hybrid photocatalyst ZnIn2S4/ZnS for high photocatalytic hydrogen generation performance

The ZnIn2S4/ZnS (ZIS/ZnS) binary hybrid photocatalysts were fabricated by modifying ZnS with ZnIn2S4 employing the facile hydrothermal method. The photocatalytic hydrogen evolution was carried out to evaluate the photocatalytic activity of the as-obtained samples. The results indicated that the 5 %ZIS/ZnS exhibits the best photocatalytic performance with a hydrogen generation rate of 8502 μmol g−1h−1. The enhanced photocatalytic performance can be ascribed to the introduction of ZnIn2S4, whose unique optimized structures, electronic structures and charge mobility and separation are in favor of the light-harvesting ability and separation and transfer of charge carriers.

Synergistic effect of Pd-Co3O4 nanoparticles supported on coffee-derived sulfur, nitrogen-codoped hierarchical porous carbon for efficient methanolysis of NaBH4

Sulfur, nitrogen-codoped (SN-doped) highly porous carbon nanostructures (CNSs) are established as efficient components for hydrogen generation applications. Waste coffee grounds are carbonized in situ and activated with KOH to produce hierarchically SN doped porous carbon nanostructures with a large specific surface area of 2320 m2 g−1. The amorphous and highly active Pd-Co3O4 nanoparticles (NPs) are anchored onto an SN-codoped carbon nanosheet prepared via a simple hydrothermal reaction. An effective method for optimization of the Pd-Co3O4/SN-CNS-600 catalytic efficiency for NaBH4 methanolysis using sodium sulfide as a precursor or combination of sulfur-containing salts as a raw material is proposed. The Pd-Co3O4/SN-CNS-600 catalyst exhibits an excellent catalytic activity for NaBH4 catalytic methanolysis at room temperature, with a high hydrogen generation rate of 20158 mL H2 min−1 gcat−1. The methanolysis reaction activation energy in an aqueous NaBH4 solution is approximately 14.52 kJ/mol. The excellent Pd-Co3O4/SN-CNS-600 catalytic activity is attributed to the small size and amorphous state of Pd-Co3O4 NPs, good synergistic interaction between Pd-Co3O4 NPs and SN-CNS with a large specific surface area, and abundant defects. Highly efficient, inexpensive, and environment-friendly catalysts are successfully developed for hydrogen generation.

Magnetic recyclable catalysts with dual protection of hollow Co/N/C framework and surface carbon film for hydrogen production from NaBH4 hydrolysis

NaBH4 (10.8 wt% theoretical hydrogen storage capacity) is an ideal hydrogen carrier, but its hydrolysis reaction at room temperature requires high-efficiency catalysts for activation and acceleration. Structured catalysts can effectively inhibit metal particle agglomeration. However, metal particles fall off the surface of the support during testing. Therefore, we report a magnetic recyclable hollow shell material H-Co/N/C-Ru@C-T. The dual protection of carbonized ZIF-67 as a framework and surface-coated carbon film makes it show good catalytic activity and durability in NaBH4 hydrolysis reaction. The hydrogen generation rate (HGR) is as high as 9815.82 mLH2 min−1 g−1, and the activation energy (Ea) is reduced to 26.9 kJ mol−1. Moreover, it retains 81.3% of its initial catalytic activity even after 25 hydrolysis cycles. Through a series of characterization, such as electron scanning spectroscopy and inductively coupled plasma atomic emission, the improvement effect of using hollow Co/N/C as framework and coating carbon film on surface on the catalytic activity and durability of H-Co/N/C-Ru@C-650 is systematically revealed. We believe this work is of unusual significance on exploring novel hydrogen storage material catalysts, especially providing opportunities for the improvement of catalytic activity and durability of catalysts.