Hydrogen Generation Reaction Research Articles

High-Valence Metal Doping Induced Lattice Expansion for M-FeNi LDH toward Enhanced Urea Oxidation Electrocatalytic Activities.

The precise design of low-cost, efficient, and definite electrocatalysts is the key to sustainable renewable energy. The urea oxidation reaction (UOR) offers a promising alternative to the oxygen evolution reaction for energy-saving hydrogen generation. In this study, by tuning the lattice expansion, a series of M-FeNi layered double hydroxides (M-FeNi LDHs, M: Mo, Mn, V) with excellent UOR performance are synthesized. The hydrolytic transformation of Fe-MIL-88A is assisted by urea, Ni2+ and high-valence metals, to form a hollow M-FeNi LDH. Owing to the large atomic radius of the high-valence metal, lattice expansion is induced, and the electronic structure of the FeNi-LDH is regulated. Doping with high-valence metal is more favorable for the formation of the high-valence active species, NiOOH, for the UOR. Moreover, the hollow spindle structure promoted mass transport. Thus, the optimal Mo-FeNi LDH showed outstanding UOR electrocatalytic activity, with 1.32V at 10mA cm-2 . Remarkably, the Pt/C||Mo-FeNi LDH catalyst required a cell voltage of 1.38V at 10 mA·cm-2 in urea-assisted water electrolysis. This study suggests a new direction for constructing nanostructures and modulating electronic structures, which is expected to ultimately lead to the development of a class of auxiliary electrocatalysts.

Marrying plasmonic earth-abundant metals with catalytic metals for visible-light-promoted hydrogen generation on biobased materials

Bimetallic CuPt alloyed nanoparticles were conveniently synthesized on biohydrogels and were capable of carrying out hydrogen release from ammonium borane hydrolysis. The biohydrogel consisted of bead-shaped alginate chains crosslinked by calcium ions, which were used as support material to synthesize and stabilize the bimetallic nanoparticles, employing adsorption and coreduction strategy steps. The as-prepared nanoparticles exhibited light absorption in the visible range (580 nm) resulting from the surface plasmon resonance (SPR) phenomenon ascribed to the presence of copper in the alloyed system. On the other hand, the presence of platinum atoms in these nanoalloys endows them with a notable catalytic performance toward ammonia borane hydrolysis as a hydrogen release reaction, reaching kr values from 0.32 × 10−4 to 2.23 × 10−4 mol L−1 min−1 as the Pt content increases. Finally, by taking advantage of the SPR light absorption shown by CuPt 1:1, it was demonstrated that these entities could be successfully employed as photocatalysts for the hydrogen generation reaction, boosting its activity by almost 2.06 times compared to its performance in dark conditions. This catalytic enhancement was mainly ascribed to the light-harvesting properties promoted by plasmonic effects and the specimen's metallic composition.

Hydrogen production from Al catalytic hydrolysis using highly active Nano composite CaO-AlOOH/Graphene oxide (GO) catalysts derived from eggshell and cauliflower stems

The hydrolysis of lightweight Al-based materials to produce hydrogen is a promising technology for compact hydrogen fuel cell production. However, developing nanostructures on a wide scale and at a low cost remains a major challenge. Herein, the high catalytic effect of CaO-γ-AlOOH/Graphene Oxide (GO) Nanocomposites (NCs) catalyst for hydrogen generation from Al and H2O reaction is discussed. These γ-phase aluminum oxyhydroxide Nanorods (NRs) (γ-AlOOH) on GO were synthesized through a simple hydrothermal method. High crystalline CaO-γ-AlOOH/GO NCs prepared bya mechanical grainingwithCaO nanoparticles (NPs). Experimental results show that small amounts of GO and CaO composite into γ-AlOOH NRs have high catalytic performance on the Al/H2O reaction for hydrogen generation at 25℃. In the catalysis process, the presence of oxygen on the catalyst surface promotes the formation of hydroxyl groups through a chemisorption process, further enhancing the catalytic activity. Because of high OH– concentrations in the local domain with a rise in the amount of Al(OH)3 precipitate byproduct, Al corrodes quickly and totally in a weak alkaline solution (pH < 8) after several contributions of Al batches. Accordingly, this research developed an excellent prediction for considering the Al reaction rate with H2O using CaO and/or GO composite crystalline γ-AlOOH catalyst.

Process integration of hydrolysis and hydrogen generation processes in the six-step Cu-Cl cycle for green hydrogen production

The ICT-OEC six-step Cu-Cl cycle dissociates water thermochemically to produce hydrogen and oxygen. In the Cu-Cl cycle integrating the hydrolysis and hydrogen processes poses a crucial engineering challenge. Hydrolysis at 350-400 °C requires extra steam, resulting in the generation of dilute HCl instead of dry HCl gas, which must be recycled for hydrogen production. To address this, pressure swing distillation (PSD) is integrated into the hydrolysis and hydrogen generation reactions to separate HCl and water. The study examines operating parameters in PSD processes. A simulated process integration model includes an intermediate heat recovery steam generator (HRSG) with PSD to complete the overall conceptual design. The nuclear-based Cu-Cl cycle without PSD demonstrates a lower environmental impact when compared to the Cu-Cl cycle with PSD. The Cu-Cl cycle with a higher HCl concentration in PSD feed exhibits a minimum global warming potential (GWP) value of 2.53 kg of CO2 eq for 1 kmol/h hydrogen production.

Synthesis of Platinum Nanoparticles Supported on Fused Nanosized Carbon Spheres Derived from Sustainable Source for Application in a Hydrogen Generation Reaction

The dwindling supply of fossil fuels has prompted the search for an alternative energy source that could effectively replace them. Potential renewable energy sources such as solar, wind, tidal, and geothermal are all promising but each has its own drawbacks. Hydrogen gas on the other hand can be combusted to produce energy with only water as a byproduct and can be steadily generated via the aqueous media hydrolysis reaction of Sodium Borohydride (NaBH4). This study successfully synthesized fused carbon spheres derived from sugar and decorated them with platinum nanoparticles to form a novel composite material (PtFCS) for catalyzing this reaction. The platinum nanoparticles were produced by reducing chloroplatinic acid in a solution with sodium borohydride and using sodium citrate as a capping agent for the nanoparticles. Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were used to characterize and determine the size and shape of the Pt nanoparticles (PtNPs) and fused carbon spheres. TEM was able to determine the average size of the fused carbon spheres to be 200 nm and the average size for the PtNPs to be 2–3 nm. The PtFCS composite was tested for its ability to catalyze the hydrolysis of NaBH4 under various reaction conditions including various solution pH, various temperatures, and various dosages of sodium borohydride. The catalyst was found to perform the best under acidic solution conditions (pH 6), producing hydrogen at a rate of 0.0438 mL/mgcat·min. The catalyst was determined to have an activation energy of 53.0 kJ/mol and could be used multiple times in succession with no loss in the volume of hydrogen produced. This sugar-derived composite catalyst shows promise and could be implemented as a sustainable catalyst for the generation of hydrogen fuel.

Sun-light driven hydrogen generation by Pd/Rb2O cocatalysts: Escalate the utility of rutile TiO2 for photocatalytic water splitting

Rising consumption and cost of fossil fuels invite the researchers to discover the renewable energy sources. Herein, a novel approach to enhance the photocatalytic performances of rutile-TiO2 has been revealed. To boost the hydrogen generation reactions, Pd/Rb2O cocatalysts have been deposited over TiO2 via chemical reduction. The morphology and optical characteristics of catalysts were demonstrated by XRD, Raman, UV-Vis/DRS, SEM and TEM analysis. Surface properties, particle sizes, and chemical composition were examined via AFM and XPS techniques. The H2 production activities were monitored by GC-TCD (Shimadzu-2010/Japan). Comparatively, Pd1.8/RbO0.2@TiO2 was found most active catalysts that can deliver hydrogen 22.74 mmolg−1h−1. Higher H2 generation activities were attributed to the presence of Pd and Rb2O cocatalysts. Rb2O promoted electrons from TiO2 to Pd active sites by elevation in fermi energy levels to attain the equilibrium during photoreactions. The mechanistic approach for higher electron transportation and better charge separation has been demonstrated and discussed over here. On the basis of results, it can be concluded that the work reported here in is reliable for sustainable energy applications.

Hydrogen generation by hydrolysis of solid sodium borohydride for portable PEMFC applications

In this paper, the hydrogen generation by the hydrolysis of solid sodium borohydride was studied. A novel NiCoP/RC catalyst that loads Ni, Co, and P complexes on resin carbon (RC) was prepared to accelerate the hydrolysis. The hydrogen generation rate, reaction temperature, hydrogen output and water-hydrogen ratio during the reaction were recorded. In comparison to the commonly used cobalt chloride catalyst, the NiCoP/RC catalyst demonstrated superior catalytic activity. Citric acid was used to neutralize the alkaline by-products, and while the mixture of NiCoP/RC catalyst and citric acid increased the hydrogen output, it resulted in lower water utilization rate. Therefore, intermittent water feeding from the bottom of the reactor was proposed, which was found to be beneficial in terms of both hydrogen output and water utilization. Finally, the study warns about the potential for thermal runaway during the hydrolysis reaction of solid sodium borohydride.

Recent Advances and Perspectives in Ru Hybrid Electrocatalysts for the Hydrogen Evolution Reaction

The water-splitting reaction for green hydrogen generation requires highly efficient catalysts on the side for the hydrogen evolution reaction (HER), and metal ruthenium (Ru) is considered a promising catalyst as a result of its similar property in hydrogen-bonding ability but low cost compared to Pt-based materials. The performance is further boosted by the recently developed hybrid Ru-based electrocatalysts. To reveal the relationship between the hybrid catalyst systems and activity for Ru-based catalysts, the research progress of heterostructured Ru hybrid catalysts in the HER is reviewed in this effort. The enhancement of HER activity of Ru hybrid catalysts is first described on the basis of the synergistic effect, strain effect, and electronic effect, and then, the latest progress is discussed in three categories of single ruthenium catalysts, ruthenium-related compounds, and ruthenium alloy catalysts. It is concluded that the heterostructured interface engineering strategy plays an important role in enhancing the activity of Ru-based catalysts in the HER. In the end, the actual problems and challenges are discussed, e.g., the intrinsic activity and stability, application in the real device, etc. It is recommended to pay attention to the long-term stability, performance, and structural evolution as well as the application of the catalysts in the devices. It is hoped that this effort will help with understanding the progress of Ru-based hybrid catalysts in the field of HER catalysis.

Built in electric-field active 2D β-BN/ZIS coated water-fed photoelectrode for methane conversion into hydrogen gas and VAPs through non-oxidative coupling

The photocatalytic conversion of methane into value added products with an add on power generation offers new sustainable solution for the GHG and commercial methane reforming. In present study photo-electrochemical conversion of CH4 gas into H2 gas and other value-added products like C2H6, C3H8, and C4H10 gas under ambient conditions through non-oxidative coupling of CH3* radicals at chain termination were investigated. Interfaces between two photocenters hinder the charge mobility therefore, built-in electric field induced VDW heterojunction of 2D/2D β-BiNbO4/ZnIn2S4 is constructed to enhance the spatial separation of excitons. Additionally, to remove the bubble diffusion challenge of gas to liquid phase 2D β-BiNbO4/ZnIn2S4 coated PES Air-photoanode is adopted. It presented gas phase photocatalysis redox reaction of alkylation and significant hydrogen generation. Presence of porous morphology and polar group in PES increased the ECSA and performance of photoanode by reducing the Rs, Rct and accumulation layer impedances. Electrochemical analysis also proven the potency of VDW 2D β-BN/ZIS for substantial hydrogen generation. 14.2% light-to-hydrogen efficiency with 61% selectivity was observed which is much higher than most of the reported LTH efficiency of photo fuel cell. The light-to fuel (LTF) efficiency is more than 17.3% and 49.7 mW/m2 of power production providing an opportunity to oxidise the methane under the ambient environment into energy-rich derivatives along with electricity generation.

Enhanced [formula omitted] sites with substitutional defects of [formula omitted] on Zn(O,S) for high-rate hydrogen generation under simulated solar-light irradiation

Carbon-free fuels are required to meet the net-zero emission in 2050 and hydrogen fuel is promising as the future solution. In this work, the hydrogen-evolved Zn(O,S) photocatalyst is improved by doping Li into its lattice with different amounts of LiNO3 precursor. The single phase of Li-doped Zn(O,S) has been confirmed with XRD and TEM analysis. In addition, the electrochemical and optical properties of catalysts are studied with EIS, TPC, DRS, and PL analyses. Li-ZnOS-10 exhibits interesting behaviors with a lower charge transfer resistivity, good photoresponse, and lower PL emission, suggesting it is a promising photocatalyst material. The as-prepared catalysts are tested for hydrogen generation reaction with simulated solar-light illumination. Li-ZnOS-10 catalyst can produce ∼15 mmol/gh and convert 30 ppm nitrobenzene to aniline entirely in 3 h. XPS analysis indicates a low amount of Li dopant in Zn(O,S), implying the formation of LiZn− surface defect that attracts the H+ to longer its lifetime for hydrogenation reaction. Furthermore, the indicated oxygen vacancy sites (VO2+) also play a crucial role in interacting with nitrobenzene and trapping electrons during photoreaction. This work demonstrated improved hydrogen generation reaction and the possible application for green chemical conversion.

Europium Molybdate/Molybdenum Disulfide Nanostructures with Efficient Electrocatalytic Activity for the Hydrogen Evolution Reaction

The design of hybrid nanostructures of molybdenum disulfide (MoS2) has been extensively explored as potent electrocatalysts for hydrogen generation reactions. Here, we report the in situ synthesis of a nanocomposite containing europium molybdate [Eu2(MoO4)3] and molybdenum disulfide (MoS2) for an enhanced electrochemical hydrogen evolution reaction (HER). The characteristic X-ray diffraction (XRD) peaks of both 2H–MoS2 and α-Eu2(MoO4)3 confirm the formation of the nanocomposite. The nanoflower (NF) architecture of MoS2 coupled with flakes of europium molybdate is observed in the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images, which lead to an enhanced surface area of the nanocomposite. Raman and X-ray photoelectron spectroscopy (XPS) studies reveal a variation in the layer thickness of MoS2 and a significant interfacial electronic interaction between Eu2(MoO4)3 and MoS2. As evident from the small onset potential of −0.05 V vs reversible hydrogen electrode (RHE) and a lower overpotential value of 186 mV (at a current density of 10 mA/cm2), the nanocomposite outperforms pristine MoS2 nanoflowers in terms of electrocatalytic HER. The charge-transfer resistance of the nanocomposite (80.02 Ω) is significantly low compared to pristine MoS2 (158.37 Ω), thus confirming the enhanced interfacial charge transfer. The Tafel slope value of the nanocomposite (189 mV/dec) is notably less than that of pristine MoS2 (313 mV/dec), indicating the enhanced HER activity of the nanocomposite. The fabrication of lanthanide-containing MoS2 nanocomposites appears to be promising for an efficient electrocatalytic activity for the hydrogen evolution reaction.

The influence of the size of a one-faced metallic head in Janus nanoparticles as a co-catalyst on the photocatalytic efficiency of hydrogen evolution under vis light irradiation

Janus nanoparticles (NPs) consisting of MoOxSy nanospheres and silver (Ag) head, successfully developed by a simple, controlled method were in the first time they were applied as a co-catalysts in photocatalytic hydrogen generation reaction under vis light irradiation (λ > 420 nm). The MoOxSy-Ag as a co-catalysts were deposited on the obtained ZnIn2S4 microspheres (ZIS) using physical absorption method. The influence of the size of a one-faced metallic head (Ag) in JNPs as a co-catalyst on the photocatalytic efficiency of hydrogen evolution has been investigated. Sample 2.5-Ag-MoOxSy@ZIS with the co-catalyst with the smallest head in the range of about 61–71 nm was characterized by 34 times higher photocatalytic hydrogen generation activity compared to pure ZIS. JNPs as a co-catalyst are characterized as asymmetric structure and precisely adjusted interface and thus, they influence on a very good electron mobility in hybrid metal-semiconductor nanostructures. JNPs can be a new alternativity to metal co-catalysts used in a photocatalytic hydrogen production reaction.

Reaction mechanism between Gen (n = 2–5) clusters and single water molecule based on density functional theory

AbstractThe ground state structures of Gen (n = 2–5) clusters and their adsorption energy values with single water molecule were calculated using density functional theory. We also investigated the reaction pathways between Gen (n = 2–5) clusters and single water molecule. Based on molecular orbital and natural population analysis (NPA) figures, it was found that the O atom in H2O binds to the Gen (n = 2–5) clusters to form GenO (n = 2–5) and releases hydrogen. Notably, the Ge2 cluster exhibited the most efficient interaction with single water molecule based on the comparison of the energy values during the reaction of hydrogen generation. Furthermore, NPA and density of states analyses indicate that the Ge atoms in the products did not reach their highest oxidation state, suggesting that GenO (n = 2–5) may continue to react with more water molecules to generate hydrogen. Our results provide a deeper understanding of the chemical reaction properties.

Photoelectrochemical Conversion of Sewage Water into H2 Fuel over the CuFeO2/CuO/Cu Composite Electrode

This study describes the synthesis of delafossite, CuFeO2, as a primary photocatalytic material for hydrogen generation. A photoelectrode, CuFeO2/CuO/Cu, was prepared by combusting a Cu foil dipped in FeCl3 in ambient air. This photoelectrode showed excellent optical behavior for the hydrogen generation reaction from sewage water, producing 90 µmol/h of H2. The chemical structure was confirmed through XRD and XPS analyses, and the crystalline rhombohedral shape of CuFeO2 was confirmed using SEM and TEM analyses. With a bandgap of 1.35 ev, the prepared material displayed excellent optical properties. Electrochemical measurements for H2 gas generation were carried out using the CuFeO2/CuO/Cu photoelectrode, comparing the effect of light and dark and monochromatic wavelength light. The electrode exhibited significant enhancement in light compared to dark, with current density (Jph) values of −0.83 and −0.1 mA·cm−2, respectively. The monochromatic light also had a noticeable effect, with the Jph value increasing from −0.45 to −0.79 mA·cm−2 as the wavelength increased from 640 to 390 nm. This system is cheap and durable, making it a promising solution for hydrogen gas fuel generation in the industry.

Hydrogen generation from metal chloride doped sodium-borohydride by thermolysis at low temperature: The effect of material preparation methods

NaBH4 /additive materials were synthesized using the facile solution, wet ball-milling, and dry ball-milling methods. The materials 10(additives)/NaBH4 (additives = MgCl2, CaCl2, MnCl2, FeCl2, NiCl2 and ZnCl2) were also prepared by Facile solution method. Thermolysis using a flow reactor studied the synthesized materials for hydrogen generation. The synthesized materials’ properties were evaluated by using the X-ray diffraction, TGA, FE-SEM, Particle Size Distribution (PSD), Raman spectroscopy, and Fourier Transform Infrared spectroscopy characterize (FTIR). The additive/catalyst optimum-loading was found to be 30 wt%, 50 wt%, and 50 wt% of CaCl2 for hydrogen generation from sodium-borohydride for the facile solution, wet ball-milling, and dry ball milling method, respectively. Adding additives, CaCl2 decreased the activation energy for the thermolysis of NaBH4 at 100 oC. This resulted in increased generation of hydrogen at 100 oC. The generation of hydrogen was ∼3.68 wt% with 50CaCl2/NaBH4 (WBM)> ∼3.63 wt% 50CaCl2/NaBH4 (DBM)> ∼1.74 wt% with 30CaCl2/NaBH4 (FS) at 100 ℃. The study suggests that the synthesis method plays an important role in the thermolysis reaction for hydrogen generation, and the wet ball-milling method was the most suitable.

Zn3(PO4)2 Protective Layer on Zn Anode for Improved Electrochemical Properties in Aqueous Zn-ion Batteries

&lt;p&gt;Aqueous zinc-ion batteries are considered as promising alternatives to lithium-ion batteries for energy storage owing to their safety and cost efficiency. However, their lifespan is limited by the irreversibility of Zn anodes because of Zn dendrite growth and side reactions such as the hydrogen evolution reaction and corrosion during cycling. Herein, we present a strategy to restrict direct contact between the Zn anode and aqueous electrolyte by fabricating a protective layer on the surface of Zn foil via phosphidation method. The Zn&lt;sub&gt;3&lt;/sub&gt;(PO&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt; protective layer effectively suppresses Zn dendrite growth and side reactions in aqueous electrolytes. The electrochemical properties of the Zn&lt;sub&gt;3&lt;/sub&gt;(PO&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt;@Zn anode, such as the overpotential, linear polarization resistance, and hydrogen generation reaction, indicate that the protective layer can suppress interfacial corrosion and improve the electrochemical stability compared to that of bare Zn by preventing direct contact between the electrolyte and the active sites of Zn. Remarkably, MnO&lt;sub&gt;2&lt;/sub&gt; || Zn&lt;sub&gt;3&lt;/sub&gt;(PO&lt;sub&gt;4&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt;@Zn exhibited enhanced reversibility owing to the formation a stable porous layer, which effectively inhibited vertical dendrite growth by inducing the uniform plating of Zn&lt;sup&gt;2+&lt;/sup&gt; ions underneath the formed layer.&lt;/p&gt;

Photochemical production of molecular hydrogen in the presence of substituted acridine salts

The photocatalytic properties of new representatives of the family of metal-free catalysts, 10-hydro-9-phenylacridine, 10-methyl-9-phenylacridinium chloride, and 10-phenyl-9-phenylacridinium chloride, were studied with respect to the reaction of molecular hydrogen generation in the presence of acids of different strength (HClO4, CH3SO3H, and CF3COOH) and reducing agents ([Bu4N]Cl, [Bu4N]Br, and [Bu4N]I). It was found that the strength of acids (p K a) and the nature of the reducing agent ( E 0) significantly affect the efficiency, i.e. turnover frequency (TOF), of the process under study. The amount of formed molecular hydrogen reaches its maximum in the case of the combination HClO4 and [Bu4N]I, characterized by minimal p K a and E0 values, respectively. The influence of the nature of substituents at the nitrogen atom in 9-phenylacridine on the efficiency of the molecular hydrogen production was analyzed. It was shown that the limiting stage of the process is the protonation of the formed radical.

Controlling the Hydrogen Generation Reaction from Waste Water in Oil Fields Using an Ionic Liquid.

Hydrogen production technologies are attracting widespread interest in energy technologies. The conventional methods for hydrogen production suffer from high cost, restricting their production everywhere. Here, we use waste formation water from a petroleum field and carbon steel materials to produce hydrogen. The most suitable conditions have been investigated to maximize the hydrogen yield. In addition, an ionic liquid (i.e., tributylmethylammonium methyl carbonate, BMAMC) has been used to control the hydrogen generation reaction. We reveal that the amount of hydrogen release rapidly increases with decreasing pH of the solution from 6.7 to 2.5. A further increase in temperature resulted in more amount of hydrogen release. Our study investigates the influence of chloride ions on hydrogen generation activity. The results revealed that ionic liquid BMAMC remarkably decreases the amount of hydrogen release with an efficiency of 92% at 5.08 × 10-4 M. The addition of ionic liquid BMAMC into waste formation water increases the activation energy of the hydrogen generation reaction. The Langmuir model is the best isotherm describing the adsorption of BMAMC on carbon steel. Finally, to confirm the adsorption of the ionic liquid BMAMC, scanning electron microscopy and Fourier-transform infrared spectroscopy analysis were conducted.

Facial synthesis of p-p heterojunction composites: Evaluation of their electrochemical properties with photovoltaics-electrolyzer water splitting using two-electrode system

Mixed transition metal oxides have garnered widespread interest as alternative electrocatalysts for the oxygen and hydrogen generation reactions; however, they tend to require extended synthetic routes, in addition to possessing limited electrocatalytic activities and stabilities. Herein, we report the observation of a synergistic effect between the non-precious metal oxides Mn3O4 and Co3O4 with CuO and NiO, wherein the resulting composites exhibit promising properties as catalysts for the alkaline water electrolysis process. The activities of these composites in both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) were improved compared to their counterparts, and the dynamic potentials of these processes were reduced. Importantly, low overpotentials of 202 and 380 mV were found for the CuO–Mn3O4 composite catalysts for the OER and the HER at 10 mA/cm2, respectively. In addition, electrochemical impedance spectroscopy measurements showed a reduced impedance response for the composites, which was dominated by the relaxation of the intermediate frequency associated with the adsorption of the intermediate. Furthermore, the superior catalytic activities of the composites were attributed to their structural properties, high electroactive surface areas, fast electron transport kinetics, and good chemo-electrical bonding between Mn3O4 and CuO. Importantly, merging with a marketable silicon-based solar cells, the accumulated PV-EC water splitting device obtains greater hydrogen production under stimulated solar light irradiation. This work offers a typical demonstration and respected strategies for practical large-scale solar H2 production via an economical PV-EC technology.

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.