Hydrogen Generation Rate Research Articles

In Situ Preparation of 2D Co-B Nanosheets@1D TiO2 Nanofibers as a Catalyst for Hydrogen Production from Sodium Borohydride

In this study, 2D Co-B nanosheet-decorated 1D TiO2 nanofibers (2D Co-B NS-decorated 1D TiO2 NFs) are synthesized via electrospinning and an in situ chemical reduction technique. The as-prepared catalyst showed excellent catalytic performance in H2 generation from sodium borohydride (SBH). When compared to naked Co-B nanoparticles, the catalytic activity of the 2D Co-B NS-decorated 1D TiO2 NFs catalyst for the hydrolysis of SBH is significantly enhanced, as demonstrated by the high hydrogen generation rate (HGR) of 6020 mL min−1 g−1 at 25 °C. The activation energy of hydrolysis was measured to be 30.87 kJ mol−1, which agreed with the reported values. The catalyst also showed good stability. Moreover, the effects of SBH, catalyst concentration, and temperature on the catalytic performance of 2D Co-B NS-decorated 1D TiO2 NFs were studied to gain a comprehensive understanding of the dehydrogenation mechanism of SBH. Based on these findings, we conclude that 2D Co-B NS-decorated 1D TiO2 NFs are effective catalytic materials for the dehydrogenation of SBH.

Optimization of aluminum hydrolysis reactions and reactor design for continuous hydrogen production using aluminum wire feeding

The depletion of fossil fuels and the issues caused by CO2 emissions are driving changes in global energy approaches. In this context, hydrogen emerges as a new and clean energy carrier for the near future. In this study, a system that can produce hydrogen with a constant flow rate for on-demand applications is developed. Hydrolysis reactions of aluminum are utilized for hydrogen generation. Aluminum in the form of wire is used and the feeding issues have been solved. The parameters of the hydrolysis such as the solution temperature (25–80 °C), catalyzer concentration (1–4 M NaOH), aluminum quantity and aluminum wire diameter (0.6–1 mm) were optimized by adopting the response method (RSM) and using laboratory scale experiments. Aluminum hydrolysis reactions and aluminum transformations during the reactions are investigated by performing surface analyzes of the wire. Using the optimized data, the continuous hydrolysis reactor and the aluminum feeding mechanism are designed. The aluminum wire feeding system is computer controlled using a microcontroller-based code. Hydrogen production rates up to 350 ml min−1 have been accomplished. A fuel-cell in the range of 5–30 W is fed by the hydrogen generated by the hydrolysis reactor system and the stability of the hydrogen generation rate and hence of the electricity generation is proven. One of the original aspects of this study is the development of a process that continuously produces hydrogen using commercially available aluminum.

Size transformation of Au nanoclusters for enhanced photocatalytic hydrogen generation: Interaction behavior at nanocluster/semiconductor interface

Recently, atomically precise metal nanoclusters (NCs) become a new class of photosensitizer for light energy conversion in metal-cluster-sensitized semiconductor (MCSS) system. However, fundamental understanding for the suitable combination of NCs and semiconductor is still unclear. Aside from aspects of light harvesting, energy level alignment and catalytic activity, interfacial interaction behavior at NCs/semiconductor interface is also crucial due to its important influence in charge transportation. In this work, the interface interaction between Au NCs and TiO2 is examined by precise transformation of Au NCs from Au22(SG)18 to Au18(SG)14, as well as its effect on photocatalytic hydrogen production activity. From the optical, charge transport and solid-states spectroscopy analyses, it is able to display that precisely tuning the number of core atoms from Au22(SG)18 to Au18(SG)14 results in the strong interface interaction between Au NCs and TiO2, reflecting in high difference of work function and modified surface band bending of TiO2, therefore promoting the injection of electrons from NCs to TiO2 and reducing interfacial charges recombination. As a result, Au18(SG)14/TiO2 shows higher hydrogen generation rate than Au22(SG)18/TiO2 under light irradiation. This work would provide new insights into rational combination of metal NCs with semiconductor and highlights the overlooked effect of interfacial interaction behavior on light energy conversion.

Glycerol Electrooxidation at Industrially Relevant Current Densities Using Electrodeposited PdNi/Nifoam Catalysts in Aerated Alkaline Media

Through glycerol electrooxidation, we demonstrate the viability of using a PdNi catalyst electrodeposited on Ni foam to facilitate industrially relevant rates of hydrogen generation while concurrently providing valuable organic chemicals as glycerol oxidation products. This electrocatalyst, in a solution of 2 M NaOH and 1 M glycerol at 80 °C, enabled current densities above 2000 mA cm−2 (in a voltammetric sweep) to be obtained in atmospheres of both air and N2. Repeated potential cycling under an aerated atmosphere to these exceptional current densities indicated a high stability of the catalyst. Through steady state polarisation curves, 1000 mA cm−2 was reached below an anodic potential of 0.8 V vs RHE. Chronoamperometry showed glycerate and lactate being the major oxidation products, with increased selectivity for lactate at the expense of glycerate in aerated systems. Aerated atmospheres were demonstrated to consistently increase the apparent Faradaic efficiency to >100%, as determined by the concentration of oxidation products in solution. The excellent performance of PdNi/Ni in aerated solutions suggests that O2 removal from the electrolyte is not needed for an industrial glycerol electrooxidation process, and that combining electrochemical and chemical glycerol oxidation, in the presence of dissolved O2, presents an important process advantage.

A novel oxidation-resistible Mg@Ni foam material for safe, efficient, and controllable hydrogen generation

As a promising in-situ hydrogen generation material, magnesium (Mg) has been seeking a promotion in its hydrogen generation property. Increasing the specific surface area, for example, replacing the Mg bulk using Mg powder, can greatly increase the hydrogen generation property, but it brings a high explosion risk, a difficulty in controlling the hydrogen generation, and an oxidation problem. In this work, we prepare a novel Mg@Ni foam material with Mg deposits on Ni foam by a physical vapor deposition method. The Ni foam not only increases the hydrolysis reaction areas of Mg by improving its specific surface area, but also kinetically accelerates the hydrolysis reaction rate of Mg by forming a uniform Mg-Ni galvanic cell. As a result, the Mg@Ni foam material realizes a near-theoretical hydrogen generation amount of Mg and a hydrogen generation rate significantly higher than those realized by the bulk Mg-based materials. The Mg@Ni foam material with the excellent hydrogen generation property is also free from explosion risk, easy to be controlled, and resistible to oxidation. A hydrogen fuel cell powered by the hydrogen generated by the Mg@Ni foam material can yield a steady voltage and run a small car for a long distance.

Exceptional activity of hollow porphyrin frameworks-confined Ni nanoparticles for hydrogen production from NaBH4 methanolysis

Hollow framework materials have recently attracted broad interest owing to the multifarious superiorities, such as large surface area, adjustable pore structure, short transport distance, as well as high permeability. Herein, a nitrogen-rich hollow porphyrin framework (H-POF) was synthesized via SiO2 as hard template. Then, ultrafine Ni nanoparticles (NPs) were confined on the surface of H-POF via ultrasonic impregnation reduction method. The resultant Ni/H-POF catalyst shows an extraordinary catalytic performance toward the methanolysis of NaBH4, providing a hydrogen generation rate (HGR) value of 34720 mL·min−1·gmetal−1, which surpasses all heterogeneous catalysts ever reported with NaOH. Further experimental investigation confirms that the high catalytic activity can attributed to the large specific surface area and hollow structure of the support, small size of metal NPs, as well as the electron-donating effect of nitrogen atoms on metal NPs. Based on isotopic experiments, the breaking of OH bond in CH3OH is proved to be the rate-determining step (RDS) of NaBH4 methanolysis. This work provides valuable insights for rationally designing nitrogen-rich hollow framework materials for supporting ultrafine metal NPs, which will be used for the future energy-related applications.

Study on the catalytic thermal decomposition of metal-hydride (NaH) to enhance the hydrogen desorption characteristics

BackgroundSodium hydride (NaH) is considered a potential hydrogen storage material to generate hydrogen for fuel cell applications. The thermal decomposition required higher temperature, and a significant portion of NaH remains undecomposed. Thus, a suitable catalyst is required to lower the decomposition temperature and increase the hydrogen generation rate. ResultA series of catalyst/NaH hydrogen storage materials were systematically investigated. The facile solution method was used to synthesize the composite material with CaO, CaF2, and CaCl2 as catalysts. The hydrogen generation via thermolysis from the composite material was studied using in-situ flow reactors. The generated hydrogen was quantified using a gas chromatograph (GC). Adding CaO (catalyst) was beneficial to lower the thermolysis temperature of NaH, and the hydrogen generation increased from ∼0.31 wt% to ∼1.94 wt% at 100 °C. The CaO assisted in the dispersion of NaH and lowered the activation energy to decompose and generate more hydrogen by thermolysis at low temperatures. The synthesized composite materials were characterized by X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Raman spectroscopy, and Fourier Transform Infrared spectroscopy (FT-IR) studies. ConclusionThe generation of hydrogen was ∼1.94 wt% with 10CaO/NaH >1.68 wt% with 5CaO/NaH >1.61 wt% with 15CaO/NaH >1.41 wt% with 20CaO/NaH >0.31 wt% with pure NaH at 100 °C.

Solar thermo-photo catalytic hydrogen production from water with non-metal carbon nitrides

Thermo-photo catalytic water splitting for hydrogen generation is a promising method for cascade utilization of full-spectrum solar energy. Herein, two g-C3N4 catalysts were synthesized using a hard-template method with different precursors (melamine for M-CN and cyanamide for C-CN) to investigate the synergistic effect between photo and thermal energies in thermo-photo catalysis. The hydrogen production rates via different pathways, including thermo-photo catalysis (TPC), thermal catalysis (TC), and photocatalysis (PC), were investigated. Results showed that the hydrogen generation rates of M-CN and C-CN catalysts via the TPC pathway at 60 °C under full-spectrum irradiation were 808.4 μmol g−1 h−1 and 1932.9 μmol g−1 h−1, respectively, which were both higher than the sum of the hydrogen production rates via TC and PC pathways, indicating the coupling effect between the photoelectric and photothermal effects of light. The thermo-photo synergy with thermal energy converted from photothermal effect is stronger than that with thermal energy from an external heat source. The mechanism of the synergistic effect was characterized by photoelectrochemical experiments, revealing that higher temperatures promote the separation and migration of charge carriers, providing a microscopic explanation for the improved hydrogen production rate of thermo-photo catalysis.

Enhancing the efficiency of sodium borohydride hydrolysis with a novel CoB-Triton catalyst

Hydrogen is increasingly recognized as the most significant alternative solution for reducing global greenhouse gas emissions in maritime transportation. In particular, solid-state sodium borohydride (NaBH4) with its high hydrogen storage density stands out as the preferred choice due to its higher efficiency and improved safety. In present study, a surfactant-stabilized CoB catalyst was used in order to improve the hydrolysis performance of NaBH4. For this reason, the effects of Triton X-100, used as a surfactant in different quantities, on the hydrogen generation rate were tested. To characterize the prepared samples, several analytical techniques were employed, including field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), Mastersizer analysis, X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. According to findings, 40.2% faster hydrogen generation rate is obtained with CoB-Triton 150 contrary to CoB catalyst. The optimum concentrations are found as 5% NaOH and 5% NaBH4 and activation energy is 44.21 kj/mol for developed CoB-Triton 150 catalyst. Last of all, fuel cell performances show that the produced hydrogen from hydrolysis reaction through CoB-Triton 150 catalyst has nearly same fuel cell performance compared to industrial pure hydrogen. Consequently, Triton X-100 is a good candidate to improve the hydrolysis performance of NaBH4 and needs further research.

Evaluation method of hydrogen generation rate by water radiolysis in fuel debris canisters considering the radiation energy absorption rate of water dependence on particle size

ABSTRACT An evaluation method of hydrogen generation rate due to water radiolysis caused by the radiation from fuel debris stored in fuel debris canisters was developed to ensure safe transport and storage of the fuel debris resulting from the core damage accidents in the Fukushima Daiichi Nuclear Power Station. Assuming that the radiation energy absorption rate of water (F value) is 1, that is all radiation energy is deposited in water mixed with the debris, the hydrogen generation rate will be overestimated. Therefore, to consider the shielding effect of the fuel debris itself, the F value dependence on the fuel debris particle size was examined. First, the hydrogen generation rate was obtained by the hydrogen generation test using particles (maximum size of 0.355 mm) of actual crushed spent nuclear fuel pellets. Then, the hydrogen generation rates obtained by this test were compared with those estimated using the F value calculated with the particle transport calculation code, PHITS. The F value was calculated assuming a system in which a spherical fuel debris particle was located at the center of a cube containing water. The PHITS code evaluated the hydrogen generation rate conservatively using the F value calculated for a fine particle (spherical fuel debris particle diameter of 0.0001 mm).

Fabrication of ZnO/CuO nanoforests and their applicability to microbial photoelectrochemical cells

Three-dimensional ZnO/CuO nanoforests (NFRs) were fabricated via the galvanic submerged photosynthesis of crystallites in water at ambient temperature and pressure, and their photoelectrochemical (PEC) properties and applicability to microbial PEC (MPEC) cells were evaluated. ZnO/CuO NFRs irradiated with UV light for 48 h showed a high PEC current of − 2.9 ± 1.3 mA/cm2 and hydrogen (H2) generation rate of 0.63 ± 0.29 µmol/cm2/day at 0 V vs. RHE owing to their superior light absorption, large BET specific surface area, and low charge recombination. The biocompatibility of the ZnO/CuO NFRs was evaluated by assessing their influence on Escherichia coli MG1655 growth. The ZnO/CuO NFRs leached Cu2+ and inhibited bacterial growth after immersion in the medium. Cu elution could be prevented by maintaining the potential at 0.01 V vs. RHE. The ZnO/CuO NFRs can be used as photocathodes for PEC H2 generation and the MPEC-based synthesis of valuable CO2-reduction products.

Synthesis of Palladium Nanoparticles Supported over Fused Graphene-like Material for Hydrogen Evolution Reaction

The search for a clean abundant energy source brought hydrogen gas into the limelight; however, the explosive nature of the gas brings up issues with its storage. A way to mitigate this danger is through the storing of hydrogen in a hydrogen feedstock material, which contains a large percentage of its weight as hydrogen. Sodium borohydride is a feedstock material that gained a lot of attention as it readily reacts with water to release hydrogen. This study explored a novel composite composed of palladium nanoparticles supported on a sugar-derived fused graphene-like material support (PdFGLM) for its ability to catalyze the reaction of sodium borohydride in water. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), 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 catalyst used in this study. The XRD study detected the presence of palladium nanoparticles, and the EDS date confirmed the presence of 3% palladium nanoparticles. The TEM result shows the palladium nanoparticles of 5.5 nm incorporated to the graphene-like material layers. The composite contained approximately 3% palladium. In the hydrogenation reactions, it was observed that optimal reaction conditions included lower pHs, increased temperatures, and increased dosages of sodium borohydride. The reaction had the greatest hydrogen generation rate of 0.0392 mL min−1 mgcat−1 at pH 6. The catalyst was tested multiple times in succession and was discovered to increase the volume of hydrogen produced, with later trials indicating the catalyst becomes more activated with multiple uses. The activation energy of the reaction as catalyzed by PdFGLM was found to be 45.1 kJ mol−1, which is comparable to other catalysts for this reaction. This study indicates that this catalyst material has potential as a sustainable material for the generation of hydrogen.

As2O3-poly(1H-pyrrole) nanocomposite for hydrogen generation from Red Sea water with high efficiencey

This research focuses on the synthesis of a new composite material, As2O3-poly(1H-pyrrole) (P1HP), for the generation of hydrogen gas. The novelty lies in the utilization of eco-friendly and cost-effective seawater as the source of hydrogen gas. The study aims to develop a sustainable and efficient approach for hydrogen production using this novel composite material and seawater as the raw materials. The As2O3/P1HP nanocomposite is synthesized through the polymerization of 1H-pyrrole. The crystal structure and size of the nanocomposite are determined using XRD analysis, which indicates a lattice constant of 11.06 Å and a crystallite size of 4.03 nm via the Scherer equation. The surface topography is visualized using SEM and TEM, revealing the presence of both large agglomerate particles and very small particles with a size of approximately 21 nm. The nanocomposite exhibits excellent optical absorption behavior and a small bandgap of 1.73 eV, making it suitable for hydrogen generation using Red Sea water as an electrolyte. The hydrogen production rate is measured to be 21 μmole cm−1.h, while the current density (Jph) values with and without incidence light are −0.24 and −0.05 mA.cm−2, respectively. The Jph values increase from −0.09 to −0.15 mA.cm−2 as the incidence photon wavelengths increase from 440 to 730 nm, indicating an enhancement in the rate of hydrogen generation. The use of low-cost materials and a natural source of electrolyte make this approach a promising candidate for renewable energy production and hydrogen gas generation.

Design of Stable 2D Heterostructured Photocatalyst for Drastically Improved Hydrogen Generation and Unravelling the Underlying Charge Carrier Dynamics

AbstractThe design of heterostructured photocatalysts comprising of 2‐D mesoporous C3N3 (π‐conjugated bonds with one less nitrogen atom in the ring to promote the better electron transport unlike conventional g‐C3N4) donor coupled with the MoS2 acceptor by a template‐directed thermal synthesis followed by hydrothermal synthesis is presented. The formation and coupling of MoS2 through basal planes on the surface of mpg‐CN has been confirmed by the XRD, XPS (C/N ratio of the order of 1), and lengthening of the C−N bond as revealed by increasing intensity of FTIR peak (1232 cm−1), respectively. Upon optimization, MS‐mpg‐CN exhibits 10‐fold enhancement in hydrogen generation rate and efficiency (∼86500 μmolg−1 h−1, IPCE: ∼64 %) than that of observed for MS‐mpg‐C3N4 photocatalyst (∼8250 μmolg−1 h−1, IPCE: ∼5.6 %). The lower PL emission intensity, average lifetime (1.91 ns) of charge carriers, precise semicircle in Nyquist plot and higher degree of band bending (Efb −0.64 eV), higher ‘g’ value (2.0038) in the EPR imply improved charge carrier separation, transfer kinetics and formation of intimate heterojunction, respectively. Furthermore, hydrogen evolution measured for subsequent days while reusing photocatalyst shows no significant change in the activity (∼1.2 % variation over three consecutive cycles), confirming their photostability and reusability.

Effects of Bi–Sn–Pb Alloy and Ball-Milling Duration on the Reactivity of Magnesium–Aluminum Waste-Based Materials for Hydrogen Production

In the present study, composite materials were elaborated of mixed scrap of Mg-based casting alloys and low melting point Bi–Sn–Pb alloy by high energy ball milling, and their reactivity in NaCl solution with hydrogen release was tested. The impacts of the additive content and ball milling duration on their microstructure and hydrogen generation performance were investigated. Scanning electron microscopy (SEM) analysis revealed significant microstructural transformations of the particles during milling, and X-ray diffraction analysis (XRD) proved the formation of new intermetallic phases Mg3Bi2, Mg2Sn, and Mg2Pb. The said intermetallic phases were anticipated to act as ‘microcathodes’ enhancing galvanic corrosion of the base metal. The dependency of the samples’ reactivity on the additive content and milling duration was determined to be nonmonotonic. For the samples with 0, 2.5, and 5 wt.% Rose alloy, ball-milling during 1 h provided the highest hydrogen generation rates and yields (as compared to 0.5 and 2 h), while in the case of the maximum 10 wt.%, the optimal time shifted to 0.5 h. The sample activated with 10 wt.% Rose alloy for 0.5 h provided the highest ‘metal-to-hydrogen’ yield and rapid reaction, thus overperforming those with lower additive contents and that without additives.

The development of ternary-based TiO2-SnS2/GO-RGO composite material for photocatalytic H2 production under Solar light irradiation

Production of alternative fuels, such as hydrogen, by harvesting abundant Solar energy is under continuous scientific development and improvement. Accordingly, in this work TiO2-based composite materials with different wt% of SnS2 and GO-RGO were synthetized employing in-situ solvothermal method, and their activity for H2 evolution under Solar irradiation was investigated. Through the synthesis, GO was considerably reduced forming RGO. Prior testing the activity, a comprehensive characterization to elucidate structural, morphological and semiconducting properties of as-prepared materials was performed. Photocatalytic hydrogen production experiments were conducted in with sacrificial agent (TEOA). Photocatalytic tests have shown that a smaller mass ratio of SnS2 (5 wt%), and a minimal mass ratio of GO-RGO (0.01 wt%), provided the highest hydrogen generation rate of 61.5 μmol/(hgcatal) among tested materials. Hence, the higher GO-RGO material incorporation into the composite presumably blocked the photocatalytic active surface preventing intrusion of Solar irradiation necessary for the activation of material.

Versatile Bifunctional Ag@g-C3N4/r-GO Catalyst for Efficient Photo- and Electrocatalytic H2 Production

Here, we develop a series of hybrid Ag@g-C3N4/r-GO nanocomposite materials that are highly active, durable, and adaptable for electro- and photocatalytic H2 generation under visible light by employing a rapid and simple sonochemical technique. Multiple catalytic behaviors can be achieved through the strategic introduction of Ag metal into a hierarchical structure consisting of photo- and electroactive two-dimensional (2D) sheets with various band configurations. The outcomes of this work show the development of heterojunctions and show how electro- and photocatalysis were both synergistically improved. The fabricated materials were examined for photocatalytic hydrogen evolution, photoelectrocatalytic (PEC) hydrogen evolution, and electrocatalytic hydrogen evolution reaction (HER). In both photocatalytic conditions at 1.5 AM simulated light irradiation and electrocatalytic conditions, silver-doped composites showed better activity. Among all of the fabricated catalysts, the Ag20%@g-C3N4/r-GO (A20CNG) catalyst displayed the highest apparent quantum yield (AQY) of 1.69 and the highest hydrogen generation rate (954 μmol g–1 h–1). However, in the case of electrocatalysis, Ag15%@g-C3N4/r-GO (A15CNG) showed impressive HER activity with a low overpotential (η) of 0.484 V at 10 mA cm–2 current density with 130.6 mV dec–1 Tafel slope value and also exhibited approximately 16 times more current density than that of g-C3N4/GO (CNGO) at a fixed overpotential in the HER process; this was also supported by the electrochemical active surface area (ECSA). On the basis of the impressive results shown above, the Ag@g-C3N4/r-GO (ACNG) catalyst might be a promising and flexible nanocomposite for photo-, photoelectro-, and electrocatalytic hydrogen evolutions. This is the first study to our knowledge that provides the results of a comprehensive examination into the photo- and electrocatalytic application of an interesting and versatile bifunctional catalyst.

Enhanced Hydrogen Generation from Magnesium-Aluminum Scrap Ball Milled with Low Melting Point Solder Alloy.

In this investigation, composite materials were manufactured of mixed scrap of Mg-based alloys and low melting point Sn-Pb eutectic by high energy ball milling, and their hydrogen generation performance was tested in NaCl solution. The effects of the ball milling duration and additive content on their microstructure and reactivity were investigated. Scanning electron microscopy (SEM) analysis indicated notable structural transformations of the particles during ball milling, and X-ray diffraction analysis (XRD) proved the formation of new intermetallic phases Mg2Sn and Mg2Pb, which were aimed to augment galvanic corrosion of the base metal. The dependency of the material's reactivity on the activation time and additive content occurred to be non-monotonic. For all tested samples ball milling during the 1 h provided, the highest hydrogen generation rates and yields as compared to 0.5 and 2 h and compositions with 5 wt.% of the Sn-Pb alloy, demonstrated higher reactivity than those with 0, 2.5, and 10 wt.%.

Sustainable Additives for the Production of Hydrogen via Sodium Borohydride Hydrolysis

Finding stable solutions for hydrogen storage is one of the main challenges to boosting its deployment as an energy vector and contributing to the decarbonization of the energy sector. In this context, sodium borohydride (NaBH4) has been largely studied as a hydrogen storage material due to its significant advantages, such as low pressure, stability, and high hydrogen storage density. The development of catalysts and additive materials for the on-demand hydrolysis of NaBH4 for hydrogen release is a key research area. This work studies the effects of non-toxic and environmentally friendly additives for the hydrolysis process in terms of yield, lag time, hydrogen generation rate, and gravimetric density. Specifically, four additives, including sodium carboxymethylcellulose (CMC), polyacrylamide (PAM), sodium dodecyl sulfate (SDS), and β-cyclodextrin (BCD), were studied for their application in the storage and release of hydrogen. The best results were provided by the use of sodium carboxymethyl cellulose and polyacrylamide. In the first case, a hydrolysis yield of 85%, a lag time of 70 s, a hydrogen production rate of 1374 mL·min−1·gcat−1, and a storage capacity of 1.8 wt% were obtained. Using polyacrylamide as additive, a hydrolysis yield of almost 100% was achieved, although it required a significantly higher time period for complete conversion.

α-NiS/g-C3N4 Nanocomposites for Photocatalytic Hydrogen Evolution and Degradation of Tetracycline Hydrochloride

α-NiS/g-C3N4 nanocomposites were synthesized and used for photocatalytic hydrogen (H2) evolution and tetracycline hydrochloride (TC) degradation. The fabricated nanocomposites were characterized by XRD, XPS, SEM, TEM, UV-vis DRS, TRPL, and PEC measurements. Photocatalytic studies show that the hydrogen generation rate of the 15%-α-NiS/g-C3N4 nanocomposite reaches 4025 μmol·g−1·h−1 and TC degradation rate 64.6% within 120 min, both of which are higher than that of g-C3N4. The enhanced performance of the nanocomposite is attributed to the formation of a heterojunction between α-NiS and g-C3N4 that enhances visible light absorption, promotes the separation and transfer of charges, and inhibits the recombination of carriers. The photocatalytic mechanism of the α-NiS/g-C3N4 heterojunction nanocomposite is discussed in terms of relevant energy levels and charge transfer processes.