Hydrogen Generation Rate Research Articles

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.

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.

Development and assessment of a newly developed renewable energy-based hybrid system with liquid hydrogen storage for sustainable development

One of the most effective ways to address the environmental issues triggered by fossil fuels is through the use of renewable energy. In this study, clean and sustainable power and hydrogen generation with three renewable energy sources, a wind-solar-geothermal assisted hybrid plant is planned, investigated, and analyzed. An exhaustive thermodynamic performance analysis is executed to specify the system efficiency by the way energy and exergy efficiency methods. Moreover, this developed cycle comprises a solar photovoltaic (PV) unit, a triple flash geothermal power plant, wind turbines for power generation, and a hydrogen generation and liquefaction unit. Additionally, a case study for Isparta is conducted using actual data on wind speed and solar radiation. A parametric analysis, on the other hand, is conducted to figure out the consequences of the examined cycle's performance. In light of the examination outcomes, the developed plant's power rate is figured as 9942 kW. The hydrogen generation rate and sustainability index are also figured out as 0.02143 kg/s and 2.003, respectively. Finally, the proposed hybrid cycle encloses an energetic and exergetic performance of 32.755 % and 50.06 %, respectively.

Facile fabrication of N-doped heterostructured hybrid particles based on montmorillonite incorporated with g-C3N4 for enhanced hydrogen production by NaBH4 in methanol

As an alternative to the currently increasing use of fossil fuels, hydrogen has become very important as a clean energy carrier. Herein, facile fabrication of N doped-heterostructured hybrid particles based montmorillonite (M) incorporated on graphitic carbon nitride (g-C3N4) with calcination and hydrothermal nitric acid activation was performed. The N-doped heterostructured g-C3N4-M hybrid material was used as a metal-free hybrid catalyst for NaBH4 dehydrogenation in methanol for the first time. The hydrogen generation rate (HGR) of 11,200 ml min−1 g−1 in methanol was obtained. XRD, SEM, FTIR, EDS, XPS and nitrogen adsorption/desorption analyses were used to characterize the physicochemical properties of heterostructured composites. Also, the mechanism of catalytic activity was evaluated with the obtained N-doped g-C3N4-M hybrid material.

Unleashing solar energy's full potential: Synergetic thermo-photo catalysis for enhanced hydrogen production with metal-free carbon nitrides

Conventional photocatalytic hydrogen production processes are limited by their dependency on photons possessing energy levels surpassing the material's bandgap, thus restricting their ability to utilize the full solar spectrum. Conversely, in thermal catalysis, although the entire solar spectrum is accessible, high-energy photons remain underutilized, and reaction temperatures are often elevated. To address these issues, thermo-photo catalysis is proposed to effectively harness the full spectrum of solar energy under gentle conditions. In this study, a narrow-bandgap carbon nitride catalyst with a bandgap of 2.3 eV was synthesized for the specific purpose of hydrogen production from water through thermo-photo catalysis. Results revealed that under thermo-photo catalytic (TPC) conditions, impressive hydrogen generation rates of 3009.6 μmol·g−1·h−1 and 7090.7 μmol·g−1·h−1 were achieved without and with the application of an external heat source, respectively. Both of them substantially surpassed the cumulative hydrogen production rates achieved via photocatalytic (PC) and thermocatalytic (TC) pathways, demonstrating a remarkable synergy between photonic and thermal energies in the hydrogen evolution process. The synergetic factor with an external heat source applied (2.29) was lower than that without an external heat source (3.02), indicating that there is a better synergy between the photo energy and the thermal energy provided by photothermal conversion than the thermal energy supplied by external heat sources. The properties of photo-generated carriers under various temperature regimes were further examined by photoelectrochemically tests, and electron paramagnetic resonance experiments elucidated the pivotal influence of both photo and thermal energy on radical species, offering a microscopic understanding of the mechanism responsible for the enhanced hydrogen production rate in thermo-photo catalysis.

Spherical mesoporous silica-supported Ru nanoparticles for ammonia decomposition

To synthesize highly dispersed Ru nanoparticles (NPs) with desired particle size for NH3 decomposition, an appropriate support is crucial. Herein, spherical mesoporous silica (SMS) NPs with ∼3 nm pores are synthesized by a microwave-assisted evaporation-induced self-assembly method and used as support of Ru NPs for NH3 decomposition. Characterization shows that compared to Ru NPs supported on SBA-15 and fumed SiO2, Ru NPs supported on SMS (Ru@SMS) exhibit superior NH3 decomposition performance, achieving a hydrogen generation rate of 31.4 mmol·g-1 cat·min−1 at 500 °C, which is one of the highest reported values for supported Ru catalysts in NH3 decomposition. The excellent NH3 decomposition performance observed on Ru@SMS should be attributed to effective dispersion and appropriate particle size (2.22 ± 0.29 nm) of Ru NPs. This work highlights the potential of SMS as support of Ru catalyst in NH3 decomposition.

Hydrogen production on CoFe, CoFeMn and CoFeMo coatings deposited on Ni foam via electroless metal plating


 
 
 
 In this study, the catalytic hydrogen generation was evaluated on the cobalt–iron (CoFe), cobalt–iron–manganese (CoFeMn) and cobalt–ironmolybdenum (CoFeMo) coatings deposited on the Ni foam substrate using the electroless metal plating method and morpholine borane as the reducing agent. The characterisation of the surface morphology, structure and composition of resulted coatings was done using scanning electron microscopy (SEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The catalytic activity of the prepared CoFe/Ni, CoFeMn/Ni and CoFeMo/Ni catalysts was investigated for hydrogen generation from an alkaline sodium borohydride (NaBH4) solution at different temperatures. It was found that the hydrogen generation rate of ca. 5.2, 7.8 and 11.7 L min–1 g–1 was achieved by using the CoFe/ Ni, CoFeMo/Ni and CoFeMn/Ni coatings, respectively, at 343 K. Among the investigated catalysts, CoFeMn/Ni exhibits the lowest activation energy of 62.4 kJ mol–1 and the highest HGR of 11.7 L min–1 g–1 at 343 K.
 
 
 

Machine Learning Accelerated Exploration of Ternary Organic Heterojunction Photocatalysts for Sacrificial Hydrogen Evolution.

Donor-acceptor heterojunctions in organic photocatalysts can provide enhanced exciton dissociation and charge separation, thereby improving the photocatalytic activity. However, the wide choice of possible donors and acceptors poses a challenge for the rational design of organic heterojunction photocatalysts, particularly for large ternary phase spaces. We accelerated the exploration of ternary organic heterojunction photocatalysts (TOHP) by using a combination of machine learning and high-throughput experimental screening. This involved 736 experiments in all, out of possible 4320 ternary combinations. The top ten most active TOHPs discovered using this strategy showed outstanding sacrificial hydrogen production rates of more than 500 mmol g-1 h-1, with the most active ternary material reaching a rate of 749.8 mmol g-1 h-1 under 1 sun illumination. These rates of photocatalytic hydrogen generation are among the highest reported for organic photocatalysts in the literature.

Fabrication of Al-Ni Alloys for Fast Hydrogen Production from Hydrolysis in Alkaline Water

Hydrogen generation through the hydrolysis of aluminum alloys has attracted significant attention because it generates hydrogen directly from alkaline water without the need for hydrogen storage technology. The hydrogen generation rate from the hydrolysis of aluminum in alkaline water is linearly proportional to its corrosion rate. To accelerate the corrosion rate of the aluminum alloy, we designed Al-Ni alloys by continuously precipitating an electrochemically noble Al3Ni phase along the grain boundaries. The Al-0.5~1 wt.% Ni alloys showed an excellent hydrogen generation rate of 16.6 mL/cm2·min, which is about 6.4 times faster than that of pure Al (2.58 mL/cm2·min). This excellent performance was achieved through the synergistic effects of galvanic and intergranular corrosion on the hydrolysis of Al. By raising the solution temperature to 50 °C, the optimal rate of hydrogen generation of Al-1 wt.% Ni in 10 wt.% NaOH solutions at 30 °C can be further increased to 54.5 mL/cm2·min.

Regulating intragap states in colloidal quantum dots for universal photocatalytic hydrogen evolution

Understanding and manipulating intragap states in semiconductors may enable superior solar-to-hydrogen energy conversion. The effect of intragap states on photocatalysis usually remains unclear and is sometimes contradictory. Quantum-confined colloidal quantum dots (QDs) provide a unique platform to tune the density and distribution of intragap states due to their discrete energy levels. Herein, intragap active domains, composed of Cu vacancies (VCu′) and high-valent Cu (Cu*) defect states, are constructed in copper-deficient Zn-doped CuInS2 QDs. Note that these intragap states mainly exist at in-facet and on-edge defects in QDs, being away from the valence band maximum and close to Fermi level. Steady and transient optical spectra indicate that photoactivated Cu* states serving as photoinduced absorption centers can facilitate the generation of long-lived hot electrons (ca. 85 ps) as a manifestation of phonon bottleneck. Synergistically, the VCu′ states enable the holes capture and electron-hole pairs decoupling to suppress ultrafast Auger-like hot carrier cooling (ca. 178 fs). Moreover, the on-edge defects are demonstrated to play an active role in mediating proton reduction kinetics through density functional calculation. As a result, the QDs exhibit an outstanding hydrogen generation rate of 50.4 mmol g−1 h−1 without any noble metal, meanwhile, various molecule oxidation and polymer degradation can be integrated with the hydrogen generation process.