Photocatalytic release of hydrogen from ammonia borane-complex using Ni(0)-doped TiO2/C electrospun nanofibers

Preparation of Effective NiCrPd-Decorated Carbon Nanofibers Derived from Polyvinylpyrrolidone as a Catalyst for H2 Generation from the Dehydrogenation of NaBH4

The catalytic dehydrogenation of NaBH4 for the generation of H2 has a lot of potential as a reliable and achievable approach to make H2, which could be used as a safe and cost-effective energy source in the near future. This work describes the production of unique trimetallic NiCrPd-decorated carbon nanofiber (NiCrPd-decorated CNF) catalysts using electrospinning. The catalysts demonstrated exceptional catalytic activity in generating H2 through NaBH4 dehydrogenation. The catalysts were characterized using SEM, XRD, TEM, and TEM-EDX analyses. NiCrPd-decorated CNF formulations have shown higher catalytic activity in the dehydrogenation of NaBH4 compared with NiCr-decorated CNFs. It is likely that the better catalytic performance is because the three metals in the NiCrPd-decorated CNF structure interact with each other. Furthermore, the NiCrPd-decorated CNFs catalyzed the dehydrogenation of NaBH4 with an activation energy (Ea) of 26.55 KJ/mol. The kinetics studies showed that the reaction is first-order dependent on the dose of NiCrPd-decorated CNFs and zero-order dependent on the concentration of NaBH4.

Synthesis of Ilmenite Nickel Titanite-Supported Carbon Nanofibers Derived from Polyvinylpyrrolidone as Photocatalyst for H2 Production from Ammonia Borane Photohydrolysis

The present study involves the synthesis of photocatalytic composite nanofibers (NFs) comprising ilmenite nickel titanite-supported carbon nanofibers (NiTiO3/TiO2@CNFs) using an electrospinning process. The photocatalytic composite NFs obtained were utilized in hydrogen (H2) production from the photohydrolysis of ammonia borane (AB). The experimental findings show that the photocatalytic composite NFs with a loading of 25 mg had a good catalytic performance for H2 generation, producing the stoichiometric H2 in 11 min using 1 mmol AB under visible light at 25 °C and 1000 rpm. The increase in catalyst load to 50, 75, and 100 mg leads to a corresponding reduction in the reaction time to 7, 5, and 4 min. The findings from the kinetics investigations suggest that the rate of the photohydrolysis reaction is directly proportional to the amount of catalyst in the reaction system, adhering to a first-order reaction rate. Furthermore, it was observed that the reaction rate remains unaffected by the concentration of AB, thereby suggesting a reaction of zero order. Increasing the reaction temperature results in a decrease in the duration of the photohydrolysis reaction. Furthermore, an estimated activation energy value of 35.19 kJ mol-1 was obtained. The composite nanofibers demonstrated remarkable and consistent effectiveness throughout five consecutive cycles. The results suggest that composite NFs possess the capacity to function as a feasible substitute for costly catalysts in the process of H2 generation from AB.

The Catalytic Performance of Nanorod Nickel Catalyst in the Hydrolysis of Lithium Borohydride and Dimethylamine Borane

In the current global energy crisis, the value of hydrogen has become better appreciated. Metal borohydrides attract a lot of attention from researchers because they are rich in hydrogen. In this study, glass microscope slides were coated with nickel as nanorods for use as a catalyst by the magnetron sputtering method, and then catalytic hydrolysis reactions of dimethylamine borane and lithium borohydride were carried out to produce hydrogen. Parameters such as temperature, the amount of catalyst, lithium borohydride, or dimethylamine borane concentration were varied and their effects on the catalytic performances of the catalyst were examined. Moreover, the catalyst was characterized by field emission scanning electron microscopy and X-ray diffraction, and hydrolysis products were analyzed through field emission scanning electron microscopy with energy dispersive spectroscopy analyses. Reaction kinetic parameters were also determined. The activation energy values of dimethylamine borane and lithium borohydride were determined to be 40.0 kJ mol−1 and 63.74 kJ mol−1, respectively. Activation enthalpy values were also calculated as 37.34 kJ mol−1 and 62.45 kJ mol−1 for dimethylamine borane and lithium borohydride, respectively. Initial hydrogen production rates under different conditions were also investigated in the study. For both hydrolysis systems, the fastest hydrogen production rates were calculated as 109 mL gNi−1 min−1 and 103 mL gNi−1 min−1 for dimethylamine borane and lithium borohydride, respectively, in the experiment performed at 60 °C at 0.2 M substrate concentration and with 1.3 g of catalyst. These hydrolysis systems using this catalyst are good candidates for systems that need hydrogen.

Electrospun NiPd Nanoparticles Supported on Polymer Membrane Nanofibers as an Efficient Catalyst for NaBH4 Dehydrogenation

Sodium borohydride (SBH) hydrolysis in the presence of cheap and efficient catalysts has been proposed as a safe and efficient method for generating clean hydrogen energy for use in portable applications. In this work, we synthesized bimetallic NiPd nanoparticles (NPs) supported on poly(vinylidene fluoride-co-hexafluoropropylene) nanofibers (PVDF-HFP NFs) via the electrospinning approach and reported an in-situ reduction procedure of the NPs being prepared by alloying Ni and Pd with varying Pd percentages. The physicochemical characterization provided evidence for the development of a NiPd@PVDF-HFP NFs membrane. The bimetallic hybrid NF membranes exhibited higher H₂ production as compared to Ni@PVDF-HFP and Pd@PVDF-HFP counterparts. This may be due to the synergistic effect of binary components. The bimetallic Ni_1-xPd_x(x = 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3)@PVDF-HFP nanofiber membranes exhibit composition-dependent catalysis, in which Ni₇₅Pd₂₅@PVDF-HFP NF membranes demonstrate the best catalytic activity. The full H₂ generation volumes (118 mL) were obtained at a temperature of 298 K and times 16, 22, 34 and 42 min for 250, 200, 150, and 100 mg dosages of Ni₇₅Pd₂₅@PVDF-HFP, respectively, in the presence of 1 mmol SBH. Hydrolysis utilizing Ni₇₅Pd₂₅@PVDF-HFP was shown to be first order with respect to Ni₇₅Pd₂₅@PVDF-HFP amount and zero order with respect to the [NaBH₄] in a kinetics study. The reaction time of H₂ production was reduced as the reaction temperature increased, with 118 mL of H₂ being produced in 14, 20, 32 and 42 min at 328, 318, 308 and 298 K, respectively. The values of the three thermodynamic parameters, activation energy, enthalpy, and entropy, were determined toward being 31.43 kJ mol^-1, 28.82 kJ mol^-1, and 0.057 kJ mol^-1 K^-1, respectively. It is simple to separate and reuse the synthesized membrane, which facilitates their implementation in H₂ energy systems.

CuNi Alloy NPs Anchored on Electrospun PVDF-HFP NFs Catalyst for H2 Production from Sodium Borohydride

Non-noble Cu_xNi_1-x (x = 0, 0.1, 0,2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1) alloy nanoparticles supported on poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) nanofibers (NFs) are successfully fabricated. The fabrication process is executed through an electrospinning technique and in situ reduction in Cu²⁺ and Ni²⁺ salts. The as-synthesized catalysts are characterized using standard physiochemical techniques. They demonstrate the formation of bimetallic NiCu alloy supported on PVDF-HFP. The introduced bimetals show better catalytic activity for sodium borohydride (SBH) hydrolysis to produce H₂, as compared to monometallic counterparts. The Cu_0.7 Ni_0.3/PVDF-HFP catalyst possesses the best catalytic performance in SBH hydrolysis as compared to the others bimetallic formulations. The kinetics studies indicate that the reaction is zero order and first order with respect to SBH concentration and catalyst amount, respectively. Furthermore, low activation energy (Ea = 27.81 kJ/mol) for the hydrolysis process of SBH solution is obtained. The excellent catalytic activity is regarded as the synergistic effects between Ni and Cu resulting from geometric effects over electronic effects and uniform distribution of bimetallic NPs. Furthermore, the catalyst displays a satisfying stability for five cycles for SBH hydrolysis. The activity has retained 93% from the initial activity. The introduced catalyst has broad prospects for commercial applications because of easy fabrication and lability.

Hydrothermal-Assisted Synthesis of Copper Nanoparticles-Decorated Titania Nanofibers for Methylene Blue Photodegradation and Catalyst for Sodium Borohydride Dehydrogenation

Simple and inexpensive electrospinning and hydrothermal techniques were used to synthesize titania nanofibers (TiO₂ NFs) (composite NFs) decorated with copper nanoparticle (Cu NPs). The fabricated composite NFs have been tested as a photocatalytic material to degrade methylene blue (MB) as a model dye under visible light. The introduced composite NFs have shown good photocatalytic activity compared with pristine TiO₂ NFs; 100% and 50% of dye were degraded in 120 min for composite NFs and pristine TiO₂ NFs, respectively. Furthermore, composite NFs demonstrated good stability for four cycles. In addition, the fabricated Cu-TiO₂ NFs have shown good photocatalytic activity for the production of H₂ from sodium borohydride.

Fast photodegradation of antibiotics and dyes by anionic surfactant-aided CdS/ZnO nanodispersion

Photocatalytic technology has broad applications in energy and environmental science. In this study, we synthesized a type II heterojunction CdS/ZnO nanodispersion by means of one-pot precipitation. Different from previous studies,...

Catalytic and Photocatalytic Electrospun Nanofibers for Hydrogen Generation from Ammonia Borane Complex: A Review

Hydrogen (H₂) is a promising renewable energy source that can replace fossil fuels since it can solve several environmental and economic issues. However, the widespread usage of H₂ is constrained by its storage and safety issues. Many researchers consider solid materials with an excellent capacity for H₂ storage and generation as the solution for most H₂-related issues. Among solid materials, ammonia borane (abbreviated hereafter as AB) is considered one of the best hydrogen storage materials due to its extraordinary H₂ content and small density. However, the process must be conducted in the presence of efficient catalysts to obtain a reasonable amount of generated H₂. Electrospun nanofibrous catalysts are a new class of efficient catalysts that involves the usage of polymers. Here, a comprehensive review of the ceramic-supported electrospun NF catalysts for AB hydrolysis is presented, with a special focus on catalytic and photolytic performance and preparation steps. Photocatalytic AB hydrolysis was discussed in detail due to its importance and promising results. AB photocatalytic hydrolysis mechanisms under light were also explained. Electrospun catalysts show excellent activity for AB hydrolysis with good recyclability. Kinetics studies show that the AB hydrolysis reaction is independent of AB concentration and the first-order reaction of NF catalysts.

Novel Low Temperature Route to Produce CdS/ZnO Composite Nanofibers as Effective Photocatalysts

In this work, CdS/ZnO composite nanofibers (NFs) were prepared by the electrospinning of a sol–gel comprised of poly(caprolactone), zinc acetate dihydrate, cadmium acetate dihydrate, and ammonium sulfide. The electrospun NF mats were calcined under vacuum in an argon (Ar) atmosphere at 200 °C for 1 h. Standard physiochemical analysis techniques demonstrated the formation of the crystalline hexagonal phase of CdS and ZnO. Composite NFs showed good photocatalytic degradation of methylene blue (MB) dye under visible light irradiation compared to their counterparts. CdS nanoparticles, ZnO nanofibers, and composite NFs photodegraded 35.5%, 47.3%, and 90% of the MB dye, respectively, within 100 min. The reaction kinetics of MB photodegradation using the composite NFs followed the pseudo-first-order relation. Owing to their facile preparation and good photodegradation ability, the proposed method can be used to prepare various photocatalysts for wastewater treatment.

Novel magnetically separable silver-iron oxide nanoparticles decorated graphitic carbon nitride nano-sheets: A multifunctional photocatalyst via one-step hydrothermal process

Development of photocatalytic materials with magnetic and antibacterial properties is highly desirable in wastewater treatment. In this study, a novel magnetically separable silver-iron oxide nanoparticles (Ag-Fe₃O₄ NPs) decorated graphitic carbon nitride (g-C₃N₄) nanocomposite via hydrothermal treatment has been presented for the multifaceted applications. The physiochemical properties of the as-synthesized ternary nanocomposite were characterized by the field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) studies. The experimental results showed that loading of Ag on Fe₃O₄/g-C₃N₄ nanocomposite significantly improved the catalytic activity of the composite material in terms of photocatalytic degradation of methylene blue (Mdestruction of Escherichia coli (E. coli) bacteria. More importantly, the as-synthesized silver-iron oxide nanoparticles decorated graphitic carbon nitride (Ag-Fe₃O₄/g-C₃N₄) nanocomposite catalyst could be recovered by an applied external magnet and reused without the loss of photocatalytic activity. The obtained results showed that the synthesized material has potential as an economically friendly photocatalyst for environmental and energy applications.

Review of one-dimensional and two-dimensional nanostructured materials for hydrogen generation

Hydrogen is an attractive alternative to fossil fuels in terms of environmental and other advantages.