Hydrogen Generation Rate Research Articles

Monolithic CoMoB based catalyst enabling high water-sources adaptive hydrolysis of borohydrides

High water-source adaptability is meaningful to the popularization of hydrolysis of borohydrides as portable hydrogen generation technique. Herein, the key catalyst that can enable high water-sources adaptive hydrolysis of borohydrides is successfully developed for the first time. The as-prepared monolithic CoMoB based catalyst has outstanding catalytic activity with high hydrogen generation rate of the 3.0 L min−1 g−1 at 25 °C and low activation energy of 38.7 kJ mol−1 toward the hydrolysis of NaBH4 using deionized water. More importantly, the catalyst exhibits distinguished durability toward hydrolysis of borohydrides in various water, including deionized water, lake water, and even seawater benefiting from its unique structure and gas scouring effect. Furthermore, an efficient NaBH4-based H2 supply system is developed with the catalyst and this system successfully achieves full drive of 100 W fuel cell using different sources of water. This study may provide a new protocol to develop portable H2 generation system with high water source adaptability in wild environments.

Highly Active and Robust Catalyst: Co2B-Fe2B Heterostructural Nanosheets with Abundant Defects for Hydrogen Production.

A high-performance and reusable nonnoble metal catalyst for catalyzing sodium borohydride (NaBH4) hydrolysis to generate H2 is heralded as a nuclear material for the fast-growing hydrogen economy. Boron vacancy serves as a flexible defect site that can effectively regulate the catalytic hydrolysis performance. Herein, we construct a uniformly dispersed and boron vacancy-rich nonnoble metal Co2B-Fe2B catalyst via the hard template method. The optimized Co2B-Fe2B exhibits superior performance toward NaBH4 hydrolysis, with a high hydrogen generation rate (5315.8 mL min-1 gcatalyst-1), relatively low activation energy (35.4 kJ mol-1), and remarkable cycling stability, outperforming the majority of reported catalysts. Studies have shown that electron transfer from Fe2B to Co2B, as well as abundant boron defects, can effectively modulate the charge carrier concentration of Co2B-Fe2B catalysts. Density functional theory calculations confirm that the outer electron cloud density of Co2B is higher than that of Fe2B, among which Co2B with high electron cloud density can selectively adsorb BH4- ions, while the electron-deficient Fe2B is favorable for capturing H2O molecules, therefore synergistically promoting the catalytic NaBH4 hydrolysis to produce H2.

Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor.

Photocatalytic hydrogen production from water is a promising way to fulfill energy demands and attain carbon emission reduction goals effectively. In this study, a loop photoreactor with a total volume of around 500 mL is presented for the photocatalytic hydrogen evolution using a Pt-loaded polymeric carbon nitride photocatalyst under 365 nm irradiation in the presence of sacrificial reducing agents. The fluid flow pattern of the developed photoreactor was characterized experimentally and the photon flux incident to the loop photoreactor was measured by chemical actinometry. The system displayed exceptional stability, with operation sustained over 70 hours. A design of experiment (DOE) analysis was used to systematically investigate the influence of key parameters - photon flux, photocatalyst loading, stirring speed, and inert gas flow rate - on the hydrogen generation rate. Linear relationships were found between hydrogen evolution rate and photon flux as well as inert gas flow rate. Photocatalyst loading and stirring speed also showed linear correlations, but could not be correctly described by DOE analysis. Instead, linear single parameter correlations could be applied. Notably, the loop photoreactor demonstrated an external photon efficiency up to 17 times higher than reported in literature studies, while scaling the reactor size by a factor of 10.

Modulating effect of urea/melamine on Co2+/Co3+ ratio of Co3O4 microplates for rapid hydrogen generation via NaBH4 hydrolysis

The oxidation state of an active metal is vital in the hydrolysis of NaBH4 for rapid hydrogen generation since the electron-rich and electron-deficient sites facilitate BH4− and H2O adsorption. Herein, we systematically design a tunable oxidation state of Co in Co3O4 by in situ N-doing using the combination of melamine (M) and urea (U) as nitrogen precursors during thermal treatment. The oxidation state of Co was tuned via electronic interaction between N and Co. This interaction was optimized by varying the amount of N doping and calcination temperature. The types of heterocyclic nitrogen, mainly pyridinic- and graphitic-N, and their carbon matrix content are critical in controlling the Co oxidation state. Various Co2+/Co3+ ratios showed a different catalytic performance, and the catalytic activity reached its peak at the highest ratio of 2.74 due to the synergetic effect of the maximum adsorption of BH4− and H2O by Co2+ and Co3+, respectively. Consequently, an excellent hydrogen generation rate (2042 mL g−1 min−1) was achieved with a low activation energy of 46.9 kJ mol−1 of M2.5U10Co3O4-400. Hence, N doping from a dual N source significantly enhanced the hydrogen performance compared to the reported cobalt-based catalyst. Furthermore, M2.5U10Co3O4-400 is highly recyclable, implying its stability and practical application.

Kinetically promoted hydrogen generation by Ru nanoparticles decorated CoB2O4 on mesoporous carbon spheres with rich oxygen vacancies for NaBH4 hydrolysis

Developing heterostructured catalysts with highly active and reusable is an urgent task to achieve green hydrogen production via NaBH4. Herein, we proposed a novel NaCl template method, which involves solid-state physical grinding of metal salts, reducing agents and prepared carbon spheres with the participation of sodium chloride to synthesize Ru-particles decorated CoB2O4 supported on hollow mesoporous carbon nanospheres (Ru/CoB2O4@C) catalysts for efficient and durable H2 generation through alkaline hydrolysis of NaBH4. The optimized catalyst with a Ru content of 3.0 wt% exhibits a high hydrogen generation rate of 8139 mL min−1gcat-1 and a low activation energy of 33.2 kJ mol−1 for NaBH4 hydrolysis, which is one of the most efficient catalysts reported recently. The extraordinary performance is mainly attributed to the synergistic effect between Ru and CoB2O4 species and abundant oxygen vacancies, which facilitate charge redistribution and provide more active sites, thereby enhancing the catalytic activity. Density functional theory calculations support the proposed Michaelis-Menten mechanism, where BH4− and H2O are adsorbed on electron-rich Ru and electron-deficient CoB2O4 surfaces, respectively, and the reaction energy barrier for the rupture of the B-H bond as the rate-determining step is only 1.37 eV, synergistically promoting the hydrolysis of NaBH4. Our study provides an innovative method for designing efficient and stable catalysts for green hydrogen generation.

High performance hydrogen evolution energy conversion devices via p type polaron surface state modulation

The processing of solar to hydrogen energy conversion semiconductor devices strongly relies on the charge mobility and reactivity of hydrogen evolution reactions. Intrinsic defects induced polaron has been applied on the surface of Cu2O polyhedron nanoparticles to modulate the hydrogen cations reduction and hydrogen evolution reaction by high charge mobility and H atoms high selective of specific external terminated atoms. With the polaron surface state applied on truncated octahedron Cu2O nanoparticle photocathode, the water splitting efficiency achieved 2.12 % at 0.2 V working bias. The hydrogen generation rate is as high as 9.38 L/m2⋅h. Besides, under 1.23 V applied bias, at 1 atm pressure and room temperature, there are over 64 L hydrogen gases are generated in only one hour, and the hydrogen generation rate is as high as 65.39 L/m2⋅h. During this study, a defined p typed polaron surface state for raising charge mobility and hydrogen evolution in solar to hydrogen conversion system is illustrated, which provides the reliable application in related photon to electron conversion and high performance energy conversion devices.

Novel MOF/COF dual carrier anchoring Ru nanoparticles for improved hydrogen production by hydrolysis of NaBH4

Here, a facile bottom-up strategy has been employed to grow metal organic frameworks on covalent organic frameworks, forming a ZIF-67/JUC-505 dual-carrier material for the first time. Subsequently, ultrafine Ru nanoparticles (NPs) were loaded onto it through hydrogen reduction, resulting in the Ru-(ZIF-67/JUC-505) catalyst. Transmission Electron Microscope and Brunauer Emmett Teller analysis indicate that ZIF-67/JUC-505 possesses a porous structure with both micropores and mesopores, and the ruthenium anchored on it forms ultrafine Ru nanoparticles (< 2 nm). The specific surface area of Ru-(ZIF-67/JUC-505) obtained is 638.8 m²·g⁻¹ . The study on performance of NaBH4 hydrolysis illustrates that Ru-(ZIF-67/JUC-505) with 2.38 wt% Ru NPs has the highest catalytic activity. Specifically, the hydrogen generation rate (HG rate) of NaBH4 is 34790 mL∙min−1∙g−1 at 303 K, significantly higher than Ru/ZIF-67 (2511 mL∙min−1∙g−1) and Ru/JUC-505 (3794 mL∙min−1∙g−1) single-carrier catalysts. Meanwhile, the Ru-(ZIF-67/JUC-505) catalyst also shows excellent cycling stability, that is the Ru-(ZIF-67/JUC-505) still maintained 91.0% of its initial performance after 10 cycles. The mechanistic study indicates that the cycling stability is ascribed to the dual-carrier material ZIF-67/JUC-505. Exploring novel porous hybrid materials is of great significance, and it provides potential for material separation, catalysis and other related fields.

Novel Nanocatalysts for Sustainable Hydrogen Production from Renewable Resources

This research delves into the development, manufacturing, and assessment of nanocatalysts with the purpose of producing hydrogen sustainably from renewable resources. Using the sol-gel, hydrothermal, co-precipitation, and solvothermal processes, four distinct catalysts with the labels A, B, C, and D were created, respectively. The rate of hydrogen generation, activation energy, turnover frequency, and surface area were used to assess the catalytic performance. Catalyst A outperformed Catalyst B in terms of hydrogen generation rate, with a 10% increase to 50 mmol/g/hr. Moreover, Catalyst A showed superior reaction kinetics with a lower activation energy of 50 kJ/mol. With a turnover frequency of 0.02 s^-1, catalyst C had the highest activity, indicating a higher catalytic activity per active site. Furthermore, with a surface area of 120 m^2/g, Catalyst D offered the most active locations for reactions that produce hydrogen. Environmental impact analyses showed that various catalysts used varied amounts of resources and produced varying amounts of waste. With 950 liters of water used and 45 kWh of energy consumption, Catalyst B showed the lowest use, whereas Catalyst D produced the least amount of chemical waste (6 kg). The results of the stability tests showed that the durability of the catalysts varied, with Catalyst D showing the maximum stability after 100 cycles. Overall, the results emphasize how crucial catalyst design and synthesis techniques are to the development of effective and long-lasting hydrogen generation technologies. To optimize catalyst compositions, improve stability, and scale up manufacturing for real-world applications in renewable energy systems, further research is necessary.

Ferroelectric field enhanced tribocatalytic hydrogen production and RhB dye degradation by tungsten bronze ferroelectrics.

Tribocatalysis is a method that converts mechanical energy into chemical energy. In this study, we synthesized tungsten bronze structured Ba0.75Sr0.25Nb1.9Ta0.1O6 ferroelectric ceramic submicron powder using a traditional solid-state route, and the powder exhibited excellent performance in tribocatalytic water splitting for hydrogen production. Under the friction stirring of three polytetrafluoroethylene (PTFE) magnetic stirring bars in pure water, the rate of hydrogen generation by the Ba0.75Sr0.25Nb1.9Ta0.1O6 ferroelectric submicron powder is 200 μmol h-1 g-1, and after 72 hours, the accumulated hydrogen production reaches 15 892.8 μmol g-1. Additionally, this ferroelectric tungsten bronze ferroelectric material also exhibits excellent tribocatalytic degradation ability toward RhB dyes, with degradation efficiency reaching 96% in 2 hours. The study of tribocatalysis based on tungsten bronze ferroelectric materials represents a significant step forward in versatile energy utilization for clean energy and environmental wastewater degradation.

Ferromagnetic “nickel core–cobalt shell” catalysts for NaBH4 hydrolysis

The “nickel core–cobalt shell” catalyst has been proposed for solid-state NaBH4 pellets. Calcination of nickel particles before anchoring cobalt provided enhanced ferromagnetic properties for efficient from the spent solution using a magnet.

Waste ceramic frit as novel catalyst triggering sodium borohydride methanolysis reaction

Hydrogen energy is remarkable as a clean and efficient energy source alternative to fossil fuels. In recent years, hydrogen production from methanolysis of borohydride species has been the subject of many studies. Catalysts are of critical importance in hydrogen production with NaBH4. The widespread and commercial availability of this process depends on the cost and sustainability of the catalysts. Due to the cost and environmental impacts of metal-containing or metal-doped support materials used as catalysts, low-cost, environmentally friendly, and high-activity catalysts are being investigated. For this purpose, waste ceramic frits were used as catalysts in the NaBH4 methanolysis reaction. The hydrogen generation rates (HGR) of 11 different frits were compared. The oxide contents of these frits were determined by XRF analysis, and the two frits with the highest HGR values were characterized by XRD and SEM-EDX methods. For the two frits identified by code F1 and F2, initial rates of 10,027 mL/min.gcat and 8839 mL/min.gcat were obtained at 30 °C with 0.05 g catalyst and 1.25 % NaBH4, respectively. The activation energies of F1 and F2 frits were calculated as 18.27 kJ/mol and 29.71 kJ/mol, respectively.

Cerium-Organic Framework (CeOF) for hydrogen generation via the hydrolysis of NaBH4

Hydrogen gas has been considered an eco-friendly energy source with a high energy content, making it a suitable energy carrier for several industries. A cerium-organic framework, denoted as CeOF, was synthesized by reacting cerium with a tricarboxylic organic linker using a solvothermal method. The material's characteristics were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transforms infrared spectroscopy (FT-IR) to confirm its crystallinity, phase purity, elemental composition, chemical bonding, morphology, and thermal stability. CeOF catalysized the release of hydrogen from solid hydrogen storage materials, e.g., sodium borohydride (NaBH4) by the reaction with water via hydrolysis. An examination was carried out to analyze the influence of catalyst loading, NaBH4 weight (0.2–3 wt.%), and reaction temperature. The CeOF catalyst showed a significant hydrogen generation rate (HGR) of 1800 mLH2·gcat-1·min−1, with an activation energy of 58.8 kJ·mol−1. It showed good catalytic recyclability enabling continuous hydrogen production for four cycles without any significant decrease in the material’s performance.

A Ru atomic cluster-installed Co–Co2B nanocatalyst remarkably combats product inhibition while sustaining high turnover frequency of hydrogen production

This work unveils the Ru atomic clusters-installed Co–Co2B nanocatalyst that remarkably combats borate-based product inhibition without compromising the superior rate and turnover frequency of hydrogen generation from ammonia borane.

Study on synergistic hydrogen generation from aluminum-based composites in different forms of water.

The environmental suitability of hydrogen storage materials is significantly influenced by the way aluminum reacts synchronously with water, ice, and water steam. The straightforward ball milling process was used to synthesize Al-based composite materials with carbon nanotubes (CNTs) or graphene oxide (GO). The reactivity of the composites in various types of water was investigated. The Al/Bi/CNT and Al/Bi/GO composites may react in liquid water, low-temperature ice, and high-temperature steam. The hydrolysis promotion of Al-based composites by CNTs is superior to that of GO, whether in liquid water at 20 °C or ice at -20 °C. The maximum hydrogen generation rate of Al/Bi/CNT composites can reach 34.6 mL g-1 s-1 at 20 °C. The hydrogen generation volume of Al/Bi/CNT can reach 700 mL g-1 in 15 min on ice at -20 °C. Moreover, the ignition temperature and ignition delay time of Al/Bi/CNT are shorter than those of Al/Bi/GO in high-temperature steam. The hydrogen generation volume from Al/Bi/CNT at 200 °C can reach 853 mL g-1. These may originate from the unique one-dimensional nanostructure of CNTs, which provides more surface area or reaction sites during the hydrolysis of the composite.

Study on the effect of graphite-based materials on the reactivity of activated aluminum composites in different forms of water

For further energy enhancement of water-reactive metal fuels, it is crucial to find aluminum composites that can react synchronously and quickly with multiple types of water (ice, steam, and water). In this paper, two graphite-based aluminum composites, aluminum/bismuth/graphite (Al/Bi/GI) and aluminum/bismuth/graphene nanosheets (Al/Bi/GE), were prepared. The morphology and crystal structure of the composites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The reactivity of Al/Bi/GI and Al/Bi/GE with water from 20 °C to 80 °C and ice at 0 °C and −15 °C was characterized using hydrogen generation properties. Their ignition and combustion properties in high-temperature water steam from 300 °C to 900 °C were also investigated. The results show that Al/Bi/GI and Al/Bi/GE composites prepared by ball milling have blocky and multilayered lamellar structures, respectively. That ball milling does not result in the formation of new alloys. The thickness of graphite material affects the reactivity of activated aluminum composites. The hydrogen generation rates of Al/Bi/GE in water and ice are much higher than that of Al/Bi/GI. The maximum hydrogen generation rates of Al/Bi/GE were 28.8 and 46.6 times higher than those of Al/Bi/GI in water at 20 °C and ice at −15 °C, respectively. In high-temperature water steam, the ignition temperature and ignition delay time of Al/Bi/GE are lower than those of Al/Bi/GI. Al/Bi/GE achieves a rapid reaction that can be synchronized with three forms of water and is expected to be applied to water-reactive metal fuel propellants.

Investigation of electrooxidation and methanolysis of sodium borohydride on activated carbon supported Co catalysts from poplar sawdust

At present, the chemical activation method is used to prepare activated carbon from poplar sawdust. Co/activated carbon (Co/AC) is synthesized by the sodium borohydride (SBH, NaBH4) reduction method. The catalysts are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy-X-ray energy dispersion (SEM-EDX) analytical techniques. The catalytic activity, stability, and resistance of the Co/AC catalysts are determined by electrochemical analyses such as cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS), respectively. The 1 % Co/AC catalyst exhibits the highest catalytic activity at a specific activity of 3.964 mA/cm2 compared to other catalysts. Furthermore, it has shown long-term stability and low resistance. The effect of the catalyst, sodium borohydride and methanol amounts, and temperature parameters on the initial hydrogen generation rate are determined. The initial hydrogen generation rate of the 1 % Co/AC catalyst is obtained as 26053.2 mL/min.gcat at optimum parameters such as 0.025 g catalyst, 0.15 g NaBH4, 6 mL methanol, and 60 °C temperature. As a result, 1 % Co/AC catalyst is promising both as an anode electrode material and catalyst for sodium borohydride methanolysis.

Optimization of hydrogen generation rate with Co/MMT catalyst from NaBH4 using box-behnken method

Optimization of hydrogen generation rate with Co/MMT catalyst from NaBH4 using box-behnken method

Phase tuning of a thermal plasma synthesized cobalt oxide catalyst and understanding of its surface modification during the hydrolysis of NaBH4.

NaBH4 is an attractive candidate for closed-loop hydrogen generation in small practical applications owing to its ambient condition hydrogen release mechanism, non-toxic byproduct, ability to regenerate, and stability at ambient conditions. The hydrolysis of NaBH4 requires a catalyst to accelerate the hydrogen generation process and cobalt oxide is one such promising catalyst in this reaction. The surface species and crystalline phases of cobalt oxide catalysts play an important role in determining the hydrogen generation rate and overall hydrolysis process. In this study, cobalt oxide nanoparticles are synthesized by a thermal plasma route. The two crystalline phases, namely c-CoO and Co3O4, are tuned using thermal plasma operating conditions. The catalysts so obtained have been thoroughly characterized using analytical techniques like XRD, XPS, HR-TEM, etc. Furthermore, the catalyst was used for hydrogen production in the hydrolysis process of NaBH4. The ex situ X-ray photoelectron spectra recorded at different stages of the hydrolysis process have been extensively used to understand surface modifications occurring at the surface of the catalyst. The Co+3/Co+2 ratio and attachment of other species during hydrolysis analyzed using XPS are correlated with the overall hydrolysis reaction before and after catalysis. It was concluded that the presence of the c-CoO (i.e. initial Co+2 species presence) phase brings stability to hydrogen production in that cycle.

Enhanced sunlight-driven catalysis for hydrogen generation and dye remediation using synergistic p-Co3O4/n-TiO2 nanocomposites.

In this study, p-Co3O4/n-TiO2 nanocomposites were synthesized using different ratios of cobalt and titanium precursors through a hydrothermal method. These nanocomposites demonstrated notable potential in photocatalytic applications for hydrogen production and orange-red dye degradation under sunlight. Various techniques, including XRD, Raman spectroscopy, XPS, FESEM, TEM, and BET analysis, were used to comprehensively characterize their structural, morphological, and optical properties. The nanocomposites exhibited both cubic and tetragonal phases of Co3O4 and TiO2, and their combined effect resulted in a narrowed band gap. Additionally, the presence of Co3O4 induced surface plasmon resonance on the TiO2 surface, effectively impeding electron-hole recombination. The nanocomposites displayed an average particle size of ∼20 to 30 nm with substantial visible light absorption. High crystallinity and well-dispersed nanocomposites were confirmed by XRD and Raman, with BET surface areas ranging between 49 and 106 m2 g-1. Notably, the p-Co3O4/n-TiO2 nanocomposite showed superior photocatalytic activity, achieving a maximum hydrogen generation rate of 1120 μmol h-1 g-1 and an 83% degradation efficiency of the orange-red dye within 6 minutes under sunlight. This study emphasizes the enhanced performance of the p-Co3O4/n-TiO2 nanocomposite, indicating its potential in photocatalytic applications, conforming to a pseudo-first-order kinetics model.

Mesoporous TiO2 Single-Crystal Particles from Controlled Crystallization-Driven Mono-Micelle Assembly as an Efficient Photocatalyst.

Mesoporous materials with crystalline frameworks have been widely explored in many fields due to their unique structure and crystalline feature, but accurate manipulations over crystalline scaffolds, mainly composed of uncontrolled polymorphs, are still lacking. Herein, we explored a controlled crystallization-driven monomicelle assembly approach to construct a type of uniform mesoporous TiO2 particles with atomically aligned single-crystal frameworks. The resultant mesoporous TiO2 single-crystal particles possess an angular shape ∼80 nm in diameter, good mesoporosity (a high surface area of 112 m2 g-1 and a mean pore size at 8.3 nm), and highly oriented anatase frameworks. By adjusting the evaporation rate during assembly, such a facile solution-processed strategy further enables the regulation of the particle size and mesopore size without the destruction of the oriented crystallites. Such a combination of ordered mesoporosity and crystalline orientation provides both effective mass and charge transportation, leading to a significant increase in the hydrogen generation rate. A maximum hydrogen evolution rate of 12.5 mmol g-1 h-1 can be realized, along with great stability under solar light. Our study is envisaged to extend the possibility of mesoporous single crystal growth to a range of functional ceramics and semiconductors toward advanced applications.