Efficient Hydrogen Generation Research Articles

Noble metal free efficient photocatalytic hydrogen generation by TaON/CdS semiconductor nanocomposites under natural sunlight

Tantalum oxynitride have narrow band gap and its band potentials are suitable for visible light induced hydrogen generation. However, due to fast electron-hole recombination, the efficiency of photocatalytic hydrogen evolution reaction is very low. Herein, we have synthesized semiconductor heterojunction photocatalyst, i.e., TaON/CdS with suitable band positions by a simple precipitation method. Ratio between two semiconductors is optimized to obtain maximum hydrogen evolution. XRD, XPS and TEM analysis demonstrate the formation of heterojunction between these semiconductors. Among the synthesized catalysts, 3% TaON/CdS heterostructure exhibits the highest hydrogen evolution activity with H2 production rate of 7.5 mmol h−1 under natural solar light, whereas the rate is 11 mmol h−1 under the visible light generated by xenon (Xe) lamp without the addition of any noble metal as the co-catalyst. The CdS and 3% TaON/CdS nanomaterials show an AQE of 5.1% and 12.2%, respectively. Combination of Mott-Schottky, UPS and DR UV–visible spectroscopy studies revealed the formation of S scheme semiconductor heterojunction between these nanomaterials with valence, conduction band positions, i.e., 1.46, −0.78 eV for CdS and 2.19, −0.66 eV for TaON, respectively. These band positions help in efficient e-h pair separation to produce hydrogen from water.

Hydrogen generation ability of B-site substituted two-dimensional Can-1Tin-3Nb3O3n+1− perovskite nanosheets in photoelectrochemical cell

Many semiconductor materials have been researched for hydrogen evolution application, in which 2D nanosheet materials are given a bunch of investigation due to their suitable energy band edges and proper band gap. The studying of a novel B-site substituted 2D perovskite nanosheets, Can-1Tin-3Nb3O3n+1− (CTNO−), with a layer number n = 4, 5, and 6 shows that these n-type semiconductors have unique properties with large band gaps (3.71 – 3.78 eV). These Dion-Jacobson family members, titaniobate nanosheets, are fabricated by substituting partially transition metal Ti elements into the Nb element positions (B sites) of the niobate (NbO6) perovskite structure. A well crystalline structure and the ability in hydrogen generation are exhibited. The energy band diagrams of CTNO− (n = 4, 5, and 6) nanosheets are determined and established. The photoelectrochemical devices made of B-site substituted CTNO−nanosheets are carried out for investigating of the ability in hydrogen generation reaction. The CTNO− (n = 5) nanosheets performs the water splitting capability with the highest hydrogen generation efficiency. The hydrogen generation efficiency is improved by a p-n composite combining CTNO− (n = 4, 5, and 6) nanosheets with a conductive polymer of PEDOT:PSS. The highest efficiency of hydrogen generation is belonging to CTNO− (n = 4)/PEDOT:PSS with a hydrogen formation rate of 5.576 × 102 µmol h−1 g−1. Concerning all these performances, these Dion Jacobson phase CTNO− (n = 4, 5, and 6) nanosheets are considered for ultrathin scale photoelectrochemical cell or phototransistor applications.

Towards the quantification of the chemical mechanism of light-driven water splitting on GaN photoelectrodes.

We present results from a study addressing the unbiased water-splitting process and its side reactions on GaN-based photoelectrodes decorated with NiOx, FeOx, and CoOx nanoparticles. Observations involving physicochemical analyses of liquid and vapour phases after the experiments were performed in 1 M NaOH under ambient conditions. A water-splitting process with GaN-based photoelectrodes results in the generation of hydrogen gas and hydrogen peroxide. Quantification of the water-splitting chemical mechanism gave numerical values indicating an increase in the device performance and restriction of the GaN electrocorrosion with surface modifications of GaN structures. The hydrogen generation efficiencies are ηH2(bare GaN) = 1.23%, ηH2(NiOx/GaN) = 4.31%, ηH2(FeOx/GaN) = 2.69%, and ηH2(CoOx/GaN) = 2.31%. The photoelectrode etching reaction moieties Qetch/Q are 11.5%. 0.21%, 0.26% and 0.20% for bare GaN, NiOx/GaN, FeOx/GaN, and CoOx/GaN, respectively.

Use of hydrogen and AI as an opportunities to increase energy autarky and create business more sustainable

The article discusses the challenges and possibilities of using hydrogen and artificial intelligence (AI) to optimize energy consumption and achieve energy self-sufficiency in Polish enterprises. The current economic situation in Europe, including the global energy and economic crisis caused by the Covid-19 pandemic, broken supply chains, and geopolitical conflicts, has led to a shift towards alternative fuels and AI-supported technologies. Hydrogen is identified as a key resource for this energy transformation, with potential applications as an energy source, energy carrier, and raw material. The article highlights the importance of green hydrogen produced through electrolysis powered by renewable energy sources. The use of AI is proposed to enhance the efficiency, control, monitoring, and prediction of hydrogen generation and storage technologies. The Polish energy sector, which heavily relies on coal, is analyzed, and the need for diversification through the integration of renewable energy sources and hydrogen technologies is emphasized. The article also discusses the challenges faced by prosumers (energy producers and consumers) in the context of intermittent energy production and grid limitations. Energy storage technologies, such as electrochemical batteries and hydrogen storage, are considered as solutions to overcome these challenges. The potential of hydrogen as an energy carrier and the role of AI in controlling and optimizing energy systems are highlighted. The article concludes with a discussion of the findings and a summary of the presented information.

Integrating Co(OH)2 nanosheet arrays on graphene for efficient noble-metal-free EY-sensitized photocatalytic H2 evolution.

The development of an efficient noble-metal-free cocatalyst is the key to photocatalytic hydrogen production technology. In this study, hierarchical Co(OH)2 nanosheet array-graphene (GR) composite cocatalysts are developed. With Eosin Y (EY) as a photosensitizer, the optimal Co(OH)2-10%GR hybrid cocatalyst presents excellent photocatalytic activity with an H2 production rate of 17 539 μmol g-1 h-1, and the apparent quantum yield for hydrogen production can reach 12.8% at 520 nm, which remarkably surpasses that of pure Co(OH)2 and most similar hybrid cocatalyst systems. Experimental investigations demonstrate that the excellent photocatalytic activity of Co(OH)2-GR arises from its unique nanosheet array architecture, which can collaboratively expose rich active sites for photocatalytic hydrogen evolution and facilitate the migration and separation of photogenerated charge carriers. It is desired that this study would supply a meaningful direction for the rational optimization of the constitute and structure of cocatalysts to achieve efficient photocatalytic hydrogen generation.

Colloidal Synthesis of Semiconductor Films for Efficient Photoelectrochemical Hydrogen Generation

The semiconductor-based photoanodes have shown great potential on photoelectrochemical (PEC) hydrogen generation. Compared to the pristine semiconductor, photoanodes fabricated with doped semiconductors exhibit modulated bandgap structure and enhanced charge separation efficiency, demonstrating improved optoelectronic properties. In this work, we develop a colloidal cation exchange (CE) strategy on versatile synthesis of heterovalent doped chalcogenide semiconductor thin films with high surface roughness. Using Ag-doped CdSe (CdSe:Ag) thin films as an example, the organized centimeter-scale CdSe:Ag films with nanometer-scale thickness (thickness around 80 nm, length × width around 1.5 cm × 1.2 cm) exhibit enhanced optical absorbance ability and charge carrier density by tuning the energy levels of conduction and valence bands as well as improved electrical conductivity by Ag dopants compared to the pristine CdSe film obtained by the vapor-phase vacuum deposition strategy. In the meantime, the surface roughness of the as-prepared semiconductor thin films is also increased with abundantly exposed active sites to facilitate accessibility to water for hydrogen generation and suppress photogenerated carrier recombination. The CdSe:Ag film photoanodes exhibit superb PEC hydrogen generation performance with a photocurrent density of 0.56 mA/cm 2 at 1.23 V versus reversible hydrogen electrode, which is nearly 3 times higher than the pristine CdSe film. This work provides a new strategy on colloidal synthesis of photoelectrodes with modulated heterovalent doping and surface roughness for PEC applications.

Electrochemical activation-induced Co-Ni-Mo-O nanosheets with low crystallinity and abundant active sites for efficient and ultra-stable hydrogen generation.

Co/Ni/Mo-based oxides are promising candidates for the hydrogen evolution reaction (HER). However, these electrocatalysts often exhibit unsatisfactory HER performance due to the lack of active sites. Herein, an in situ electrochemical activation strategy is proposed to modify the surface structure of a Co-Ni-Mo-O catalyst. During the HER in an alkaline electrolyte, the Co-Ni-Mo-O nanosheets display an activation period and a rough layer with low crystallinity is then formed on the surface of Co-Ni-Mo-O nanosheets with the leaching of partial Mo species. Owing to the synergistic catalysis of multiple metal components, a large electrochemically active surface area provided by the rough surface, and fully exposed active sites in the low-crystalline structure, the activated Co-Ni-Mo-O/NF shows favorable HER activity with an overpotential of only 42 mV at -10 mA cm-2. Furthermore, it remains stable at a large current density of -250 mA cm-2 for more than 400 h, outperforming almost all the oxide-based electrocatalysts. Such an electrochemical reduction activation strategy provides a feasible way for the surface modification and targeted design of advanced catalysts.

High performance of visible-light driven hydrogen production over graphdiyne (g-CnH2n-2)/MOF S-scheme heterojunction.

Among carbon allotropes, 2D graphdiyne (GDY) possesses the merits of good ductility, strong conductivity and an adjustable energy band structure. In this study, a GDY/ZnCo-ZIF S-scheme heterojunction photocatalyst has been successfully prepared by a low-temperature mixing method. Using eosin as a photosensitizer and triethanolamine as a solvent, the hydrogen production of the GDY/ZnCo-ZIF-0.9 composite reaches 171.79 μmol, which is 6.67 and 13.5 times that of the GDY and ZnCo-ZIF materials, respectively. The apparent quantum efficiency of the GDY/ZnCo-ZIF-0.9 composite at 470 nm is 2.8%. The improved photocatalytic efficiency may be attributed to the creation of an S-scheme heterojunction structure that enables efficient separation of space charges. In addition, the EY-sensitized GDY/ZnCo-ZIF catalyst endows the GDY with a special structure to provide an abundance of electrons for the ZnCo-ZIF material, thus facilitating the photocatalytic reduction reaction to produce hydrogen. A novel perspective is presented in this study regarding the construction of an S-scheme heterojunction based on graphdiyne for efficient photocatalytic hydrogen generation.

Efficient catalytic hydrogen generation from formic acid dehydrogenation on ultrafine PdAu nanoparticles supported on modified carbon derived from rice straw

Formic acid (FA) dehydrogenation at ambient conditions is a promising route for hydrogen (H2) generation but still suffers from low activity and selectivity. Here, potassium hydroxide (KOH) and 3-aminopropyl triethoxysilane (APTES) modified porous carbon derived from the pyrolysis of rice straw (RSNPC) offers an effective support to promote the formation of ultrafine PdAu nanoparticles (NPs). Benefiting from the small sizes of PdAu NPs, the Pd0.7Au0.3/RSNPC catalyst exhibits excellent catalytic performance for FA dehydrogenation reaction with a high turnover frequency (TOF) of 6794.3 mol H2 mol catalyst−1 h−1 at ambient conditions, outperforming most of reported catalysts for FA dehydrogenation under similar conditions.

MOF-derived porous ZnO integrated with NiO and colloidal QDs for efficient hydrogen generation via a synergistic photoelectrochemical and electrochemical process

A bifunctional electrode that integrates NiO cocatalysts and QDs light absorbers exhibits a higher Jsc of 21.7 mA cm−2, providing an efficient and low-cost paradigm to generate hydrogen under both light-on and light-off conditions.

Synergistic catalysis over Ni/ZrOx for hydrogen production from hydrolysis of ammonia borane

The Ni/ZrOx-500 catalyst with a suitable metal–support interaction exhibited efficient hydrogen generation for hydrolytic dehydrogenation of ammonia borane.

Heterojunction Design between WSe2 Nanosheets and TiO2 for Efficient Photocatalytic Hydrogen Generation

Design and fabrication of efficient and stable photocatalysts are critically required for practical applications of solar water splitting. Herein, a series of WSe2/TiO2 nanocomposites were constructed through a facile mechanical grinding method, and all of the nanocomposites exhibited boosted photocatalytic hydrogen evolution. It was discovered that the enhanced photocatalytic performance was attributed to the efficient electron transfer from TiO2 to WSe2 and the abundant active sites provided by WSe2 nanosheets. Moreover, the intimate heterojunction between WSe2 nanosheets and TiO2 favors the interfacial charge separation. As a result, a highest hydrogen evolution rate of 2.28 mmol/g·h, 114 times higher than pristine TiO2, was obtained when the weight ratio of WSe2/(WSe2 + TiO2) was adjusted to be 20%. The designed WSe2/TiO2 heterojunctions can be regarded as a promising photocatalysts for high-throughput hydrogen production.

A Review of the CFD Modeling of Hydrogen Production in Catalytic Steam Reforming Reactors

Global demand for alternative renewable energy sources is increasing due to the consumption of fossil fuels and the increase in greenhouse gas emissions. Hydrogen (H2) from biomass gasification is a green energy segment among the alternative options, as it is environmentally friendly, renewable, and sustainable. Accordingly, researchers focus on conducting experiments and modeling the reforming reactions in conventional and membrane reactors. The construction of computational fluid dynamics (CFD) models is an essential tool used by researchers to study the performance of reforming and membrane reactors for hydrogen production and the effect of operating parameters on the methane stream, improving processes for reforming untreated biogas in a catalyst-fixed bed and membrane reactors. This review article aims to provide a good CFD model overview of recent progress in catalyzing hydrogen production through various reactors, sustainable steam reforming systems, and carbon dioxide utilization. This article discusses some of the issues, challenges, and conceivable arrangements to aid the efficient generation of hydrogen from steam reforming catalytic reactions and membrane reactors of bioproducts and fossil fuels.

Electrospun self-supporting double Z-scheme tricolor-typed microfiber oriented-heterostructure photocatalyst with highly effective hydrogen evolution and organic pollutants degradation

Energy shortage and environmental pollution have seriously threatened our environment, so it is urgent to develop efficient photocatalysts to solve these dilemmas. Here, we firstly designed and manufactured the self-supporting double Z-scheme [g-C3N4/polymethylmethacrylate (PMMA)]//[TiO2/polyaniline (PANI)/PMMA]//[self-assembled 3, 4, 9, 10-perylene tetraformyl diimide (PDI)/PMMA] tricolor-typed microfiber oriented-heterostructure photocatalyst (marked as TMOP) via a tri-axial parallel electrospinning. The optimized TMOP simultaneously manifests prominent hydrogen generation efficiency (536.7 μmol h−1 g−1) and splendid degradation rates for four different leuco antibiotics of ciprofloxacin (88.99%, 90 min), tetracycline hydrochloride (91.15%, 80 min), chlortetracycline hydrochloride (77.55%, 150 min), levofloxacin (69.51%,150 min) and colored dye methylene blue (92.50%, 50 min) under simulated sunlight illumination, validating perfect tri-functional features. The dramatically heightened photocatalytic activity of TMOP mainly benefits from the morphology, heterostructure and components of tricolor-typed microfiber, which not only increases the active sites, but also broadens the absorption range of solar spectrum by using the wide spectral characteristics of PDI. More importantly, the synergistic effect between conductive polyaniline and one-dimensional double Z-scheme oriented-heterostructures accelerates the oriented and rapid transmission of carriers in multiple paths, thus greatly reducing the possibility of carriers recombination and retaining the strong redox capacity of carriers. Additionally, TMOP with self-supporting feature presents remarkable recoverability. The construction mechanism of tricolor-typed microfiber and TMOP as well as double Z-schem preserving the strong redox capacity of carriers photocatalytic mechanism are advanced.

One dimensional nano-fiber structured Fe2O3/ZrO2 to enable efficient hydrogen production via water gas shift with chemical looping

Chemical looping provides a novel route to enable efficient hydrogen generation but is limited by lacking highly active and stable oxygen carriers. Here, we proposed the one-dimensional nano-fiber Fe2O3/ZrO2 for chemical looping water gas shift to produce hydrogen and studied the size effect on the redox chemistry. The results show that the reactivity and stability of nano-fibers is size dependent. Increasing the size can significantly strengthen the stability albeit reducing the activity. In particular, the nano-fiber with the diameter of ∼99 nm shows both high hydrogen yield (9.07 mmol.g−1) and stable performance over 60 redox cycles at 750 °C. Mechanism study manifests that the small size can enhance the reduction depth in the initial few cycles, leading to high hydrogen production, but at the expense of severe sintering after repetitive cycles. Therefore, the selection of an optimal size (99 nm in diameter) is key to simultaneously ensure high reactivity and stability. We anticipate that the size effect on the redox chemistry will have extensive implications for the development of efficient oxygen carriers.

Constructing abundant phase interfaces of the sulfides/metal-organic frameworks p-p heterojunction array for efficient overall water splitting and urea electrolysis

Designing efficient electrocatalysts to improve the overall water splitting and urea electrolysis efficiency for hydrogen generation can greatly solve the dilemma of energy shortage and environmental pollution. In this work, Co8FeS8@CoFe–MOF/NF heterojunction arrays were fabricated by embedding sulfides into the surface of metal-organic frameworks (MOFs) nanosheets as multifunctional electrocatalyst. The introduction of sulfide on CoFe–MOF/NF can not only adjust the electronic structure (electron-rich state) and change the surface properties (more hydrophilic), but also increase the active area to enhance the catalytic activity. The in situ Raman shows Co8FeS8@CoFe–MOF/NF is more easily to generate active species at low potentials and generates a higher content of active β-MOOH phase than CoFe–MOF/NF. Therefore, the Co8FeS8@CoFe–MOF/NF exhibits excellent oxygen evolution reaction (OER) performance with an overpotential of 213 mV at 10 mA cm−2. Furthermore, when used as a urea oxidation reaction (UOR), only an ultralow potential of 1.311 V at 10 mA cm−2. More importantly, the assembled two-electrode drives overall water splitting and urea electrolysis with cell voltages of 1.62 V and 1.55 V at 10 mA cm−2, respectively. This work provides insights into the preparation of electrocatalysts with multifunctional heterostructure arrays for hydrogen production.

Co-vacancy rich Co3O4 catalyst enables efficient hydrogen generation from the hydrolysis of ammonia borane

• Co-vacancy rich Co 3 O 4 is synthesized by using layered cobalt glycerate as a precursor. • V co -Co 3 O 4 exhibits outstanding catalytic activity for the hydrolysis of ammonia borane. • V co -Co 3 O 4 yields a high hydrogen production rate of 934 mL min -1 g Cat -1. • V co -Co 3 O 4 shows a low activation energy of 32.65 kJ mol -1 for catalytic hydrolysis. Development of efficient and economical non-precious metal catalysts for dehydrogenation of ammonia borane is an important way to store and release hydrogen. Vacancy-engineered defective catalysts with modulated electronic structure allow ideal adsorption and dissociation of reactant molecules for the optimized catalytic activity. In this study, we report a facile synthesis of cobalt-defective Co 3 O 4 (V Co -Co 3 O 4 ) nanocatalyst by the calcination of layered cobalt glycerate as a key precursor. The stacked cobalt-oxygen sheets and interlayer bound glycerate anions in a layered structure are favorable for introducing cation vacancy during calcination process. The obtained V co -Co 3 O 4 exhibits outstanding catalytic activity for the hydrolysis of ammonia borane, along with a high hydrogen production rate of 934 mL min -1 g Cat -1 and a low activation energy of 32.65 kJ mol -1 . The catalytic performance of the V Co -Co 3 O 4 catalyst can be well maintained for consecutive five cycles. The current study establishes a new example of cation vacancy strategy to facilitate the hydrolysis of ammonia borane for hydrogen generation.

β-Ni(OH)2 mediated redox catalysis for efficient hydrogen generation by reducing accumulation of bubbles in water splitting

The water-splitting efficiency depends on the design of electrodes, choice of electrode materials, and electrocatalysts for industrial and commercial use. Here, we report the design of screw pitch cylindrical electrodes deposited with β-Ni(OH)2 hexagonal nanostructures synthesized by microwave-assisted wet chemical method to overcome the accumulation of bubbles on the electrode surface. Further, β-Ni(OH)2/NiOOH coupled redox catalysis enhances electrocatalytic activities leading to a very low overpotential of 71 mV and 98 mV needed to obtain a current density of 10 mA/cm2 with a low Tafel slope of 41.2 and 32.27 mV/dec for hydrogen and oxygen evolution respectively. The remarkable hydrogen conversion efficiency of 40.39% is obtained over 250 h of electrochemical water splitting with less than 5% fluctuation. The result assures a promising method for the mass production of hydrogen fuel with high current density and long durability performance using naturally abundant materials.

Determination of critical catalyst preparation factors (cCPF) influencing hydrogen evolution

In recent years, the energy crisis has gotten worse as a result of global challenges like the pandemic and the Ukraine crisis. To solve this problem, researchers have focused on development of sustainable resources and renewable energy infrastructure for its potential as a promising and effective strategy. Hydrogen is a significant energy carrier that will fulfill global energy demand while also significantly reducing greenhouse gas (GHG) emissions in the future decades. The catalysts used in hydrogen generation have a substantial effect on hydrogen efficiency, however unknown parameters affecting catalyst activity throughout the catalyst preparation process are a major source of concern. The most essential components are to accurate determination the development conditions of the catalysts used in the hydrogen generation. The main objective is to produce hydrogen energy with high efficiency thereby reducing the currently usage of fossil fuels, which are currently used in transportation, industry, home, and commercial applications. This study's aim is to examine critical catalyst preparation factors (cCPF) that have an effect on the efficiency of the catalyst using the fuzzy DEMATEL method. In this regard, twelve cCPF were identified based on literature review and in consultation with experts and the causal relationships among critical factors were visualized with the proposed method. The results highlighted that the most critical CPF that should be tackled to improve hydrogen generation efficiency are: appropriate reduction temperature (F), and the appropriate reduction agent concentration (G), drying conditions (L), drying time (M) and calibration of instruments and equipment (N). The findings of this study can be used to researchers and decision-makers for improving the overall performance of catalysts.

Cobalt-nickel bimetal carbon sphere catalysts for efficient hydrolysis of sodium borohydride: The role of synergy and confine effect

Sodium borohydride exhibits great potential in the field of chemical hydrogen storage. A competent catalyst would accelerate its practical application for hydrogen utilization by enhance the efficiency of hydrogen generation from hydrolysis of sodium borohydride. Herein, a kind of highly efficient and durable synergistic Co–Ni bimetal inlaid carbon sphere catalyst (Co-NiΦC) was prepared by a co-pyrolysis method, of which the configuration of metal inlaid carbon sphere could effectively expose and anchor the active component by contrast with the capsule catalyst (Co–Ni@C) and supported catalyst (Co–Ni/C). Further, diverse cobalt-nickel contents of the Co-NiΦC catalysts were optimized to achieve the best hydrolysis performance of sodium borohydride. The structure-performance relationship of inlaid catalyst and the bimetallic synergistic mechanism were investigated by multiple characterization measurements and the density functional theory (DFT). As demonstrated, the inlaid Co-NiΦC-2 catalyst (Co/Ni molar ratio of 8/2) shows a promising catalytic activity of hydrogen generation rate up to 6364 mLH2·min−1·gmetal−1, a relative low reaction activation energy of 30.3 kJ/mol as well as robust durability where it still remains about 83.4% of its initial reaction rate after the fifth cycle. The outstanding performance of the optimized catalyst may ascribe to the high dispersion, remarkable Co–Ni synergy and high stabilization of the Co–Ni nanoparticles under the confinement effect of the inlaid metal-carbon sphere configuration. This work provides an alternative avenue for the application of efficient carbon-supported bimetal catalysts in the future.