Hydrolysis Of Sodium Borohydride Research Articles

Hydrogen generation by hydrolysis of alkaline NaBH4 solution doped with amorphous catalyst Co–Y2O3–B/CNTs

This investigation enhances the catalytic efficiency of Co–B/CNTs for hydrogen production via sodium borohydride hydrolysis by doping with 5%Y2O3. Such doping significantly boosts hydrogen evolution rates, with Co–Y2O3–B/CNTs achieving a production rate of 1083.43 ml g−1·min−1—surpassing Co–B/CNTs by 1.5 times and tripling that of Co–B catalysts. SEM and XRD analyses show Y2O3 doping reduces particle aggregation and maintains the catalyst's amorphous state, thereby increasing the active surface area. Furthermore, XPS analysis demonstrates that introducing yttrium into Co–B/CNTs catalysts improves their surface elemental composition and valence states. This improvement boosts catalyst performance and stability by enhancing electron transfer and particle size optimization. Optimal hydrolysis is achieved at an NaOH concentration of 2.5 mol/L, with higher concentrations diminishing hydrogen production due to increased viscosity from by-product formation. Additionally, Co–Y2O3–B/CNTs catalysts exhibit commendable durability, maintaining more than two-thirds of their initial activity after five reuse cycles, outperforming comparable catalysts to a moderate extent. These findings underscore the beneficial role of Y2O3 in the Co–B/CNTs framework, promoting Y2O3-doped catalysts for their enhanced efficiency, sustainability, and hydrogen production capabilities.

Modulating composition and electronic structure enhance the catalytic performance of Co2MO4 (M=Fe, Ni, Cu) for NaBH4 hydrolysis

The synergistic effect between metals is of great significance for improving the performance of materials, but the mechanism of synergistic catalytic of bimetallic has rarely been reported in the hydrolysis of sodium borohydride (NaBH4, SB). In this paper, a flower shaped Co2FeO4 catalyst with high catalytic performance was selected from a series of CoxM3-xO4 (M = Fe, Ni, Cu) catalysts by controlling the composition. Based on the results of XPS characterization and density functional theory (DFT) calculation, the influence of component control on catalytic performance was discussed and explained from the perspective of electronic structure, and the "valence band center" and "D-band center" descriptors were introduced into the SB hydrolysis reaction. The simulation analysis results showed that the synergistic effect between Co–Fe elements resulted in the smallest center shift of the D band, the smallest binding energy of the hydrolysis reaction, and the best promoting effect on the electronic structure, manifested as the best catalytic performance. The calculation results were consistent with the XPS characterization results and the experimental results of hydrolysis performance testing, revealing the principle of bimetallic synergistic effect on catalytic performance.

Effect of a novel metal-free green synthesis catalyst on the positive role of microwave irradiation in hydrogen production from the hydrolysis of sodium borohydride

This study demonstrates the synthesis of hydrochar, a high-value material, from watermelon seed husk, a low-value waste material, using the hydrothermal synthesis method. The microwave power effect plays an important role in the use of metal-free and environmentally friendly catalysts for the hydrolysis of sodium borohydride. The XRD, BET, SEM, and FTIR analyses characterized the catalyst. X-ray diffraction revealed the catalyst structure to be cellulosic. The surface area and total pore volume were 1.063 m2/g and 0.0195 cm3/g, respectively, in BET analysis. According to the IUPAC classification, the catalyst conformed to the type III isotherm. This study investigated how good the catalyst for the hydrolysis of sodium borohydride was when it was exposed to microwave irradiation at different microwave powers, solution temperatures, and catalyst amounts. The Langmuir-Hinshelwood and nth-order kinetic models calculated the activation energies to be 82.192 and 83.35 kJ/mol, respectively. The use of bio-waste hydrochar as a catalyst in the hydrolysis of sodium borohydride in the microwave environment shows promising results in the search for metal-free catalysts.

Enhancing hydrogen generation from sodium borohydride hydrolysis and the role of a Co/CuFe2O4 nanocatalyst in a continuous flow system

In this study, a series of cobalt-based spinel ferrites catalysts, including nickel, cobalt, zinc, and copper ferrites, were synthesized using the sol–gel auto-combustion method followed by a chemical reduction process. These catalysts were employed for accelerating hydrogen generation via the sodium borohydride hydrolysis process. A continuous stirred tank reactor was used to perform catalytic reactor tests. All samples were subjected to analysis using XRD, FESEM, EDX, FTIR, and nitrogen adsorption–desorption techniques. The results revealed that the cobalt-based copper ferrite sample, Co/Cu-Ferrite, exhibited superior particle distribution, and porosity characteristics, as it achieved a high hydrogen generation rate of 2937 mL/min.gcat. In addition, the higher electrical donating property of Cu-Ferrite which leads to the increase in the electron density of the cobalt active sites can account for its superior performance towards hydrolysis of NaBH4. Using the Arrhenius equation and the zero-order reaction calculation, activation energy for the sodium borohydride hydrolysis reaction on the Co/Cu-Ferrite catalyst was determined to be 18.12 kJ/mol. This low activation energy compared to other cobalt-based spinel ferrite catalysts confirms the catalyst's superior performance as well. Additionally, the outcomes from the recycling experiments revealed a gradual decline in the catalyst's performance after each cycle during 4 repetitive cycles. The aforementioned properties render the Co/Cu-Ferrite catalyst an efficient catalyst for hydrogen generation through NaBH4 hydrolysis.

Facile green synthesis of a novel NiO and its catalytic effect on methylene blue photocatalytic reduction and sodium borohydride hydrolysis

NiO nanoparticles were synthesized from pine cone extract by green synthesis method, which is a simple, cost-effective, environmentally friendly and sustainable method. The particle size of NiO nanoparticles was determined to be in the range of 10–25 nm by X-diffraction differential and transmission electron microscope analysis, and the bandgap energy of NiO nanoparticles was determined to be 2.66 eV. The catalytic effect of NiO nanoparticles in both microwave-assisted sodium borohydride hydrolysis and photocatalytic reduction of methylene blue was examined and it was determined that they had a high catalytic effect in both applications. It was determined that the hydrogen production rate in sodium borohydride hydrolysis was 1135 mL/g/min. The activation energy of sodium borohydride hydrolysis is 29.69 kJ/mol and 29.59 kJ/mol for the nth-order and Langmuir Hinshelwood kinetic models, respectively. In the photocatalytic reduction of methylene blue with NaBH4, it was determined that the reduction did not occur in the absence of a catalyst, but in the presence of the catalyst, the reduction occurred 98% in 3 min. It was determined that NiO nanoparticles were used five times in the photocatalytic reduction of methylene blue and the reduction efficiency for the fifth time was 93%. It was determined that the photocatalytic reduction of methylene blue was pseudo-first order and the rate constant was 1.63 s−1. It was determined that NiO nanoparticles synthesized by the environmentally friendly green synthesis method can be used as catalysts for two different applications.

Synthesis of a cobalt catalyst supported by graphene oxide modified perlite and its application on the hydrolysis of sodium borohydride

In this work, a novel catalyst for the hydrolysis reaction of sodium borohydride to produce hydrogen—graphene oxide modified perlite supported cobalt—was produced. After being exposed to 98 % H2SO4, the natural mineral perlite was calcined and then mixed with graphene oxide. To create the Co@Perlite-GO catalyst, the synthesized Perlite-GO was added to the cobalt catalyst as a supporting material. The morphological layout and nature of the sample were evaluated using different spectroscopic techniques. Comparative analysis was carried out to investigate the catalytic effects of Co@Perlite-GO and Co@Perlite catalysts on the sodium borohydride (SBH) hydrolysis reaction. When the Co@Perlite-GO catalyst containing 4 mg Co was utilized, the hydrogen production rate was 12401 ml g−1 min−1 as a consequence of the optimization procedures carried out at 298 K. Under room conditions, the reaction occurred as catalyst control (0th degree), and the standard turnover frequency (TOF) was measured to be 8615 s−1. The activation energy, enthalpy, and entropy of the reaction were measured as 53.35 kJ mol−1, 50.77 kJ mol−1, and −58 J/(mol.K) respectively. It was found that the catalyst maintained 100 % efficiency even after being used six times.

Hierarchical porous cobalt nanoparticles encapsulated in heteroatom-doped hollow carbon as an enhancing multifunctional catalyst for hydrolysis of sodium borohydride and hydrogenation of bromate in water

Multifunctional heterogeneous catalysts have been consistently explored in recent years because of their distinctive catalytic activity in different catalysis areas at once. Here, a cobalt (Co) nanoparticles encapsulated in nitrogen-doped hollow carbon (denoted as Co@NHC) is prepared by two-step modifications of acid etching and high temperature carbonization in the inert atmosphere using a peculiar polyhedral configuration Co-ZIF as an initial template. Benefiting from an intriguing polyhedral configuration hollow structure with high specific surface area and pore volume supplying plentiful active sites, Co@NHC shows exceptional catalytic activity in catalyzing hydrolysis of NaBH4 and hydrogenation of toxic bromate in water. From experimental results, Co@NHC could efficiently enhance the generation of H2 with a H2 generation rate of 1515.4 mL min−1 gcat−1 meanwhile the activation energy (Ea) calculated from Co@NHC/NaBH4 system was only 12.6 kJ mol−1. Besides, the combination of Co@NHC and NaBH4 could further reduce toxic bromate ions into bromide via catalytic hydrogenation with a maximum bromate removal capacity of 390.6 μmol g−1. More importantly, due to its strong magnetization, Co@NHC could be simply recovered after reactions, making it well-preserve the unique structure as well as catalytic activity for multiple continuous recycles in both catalytic applications. Additionally, the plausible reaction mechanisms in catalyzing hydrolysis of NaBH4 and hydrogenation of bromate were also proposed. This work has pioneered a promising approach on preparing an engrossing magnetic heterogeneous Co-based catalyst that is practically applicable in various areas of catalysis.

A stable flow hydrogen production of sodium borohydride hydrolysis using millimeter-scale Ru/Al2O3 spheres as catalyst

In this study, we investigated the performance of continuous flow hydrogen production from NaBH4 hydrolysis by loading Ru onto millimeter-scale Al2O3 spheres (0.5–1 mm in diameter) (Ru/m-Al2O3) using a simple impregnation method. The results from transmission electron microscopy (TEM) and N2 adsorption and desorption revealed that Ru particles, with an average size of 2.73 nm, were evenly distributed on the Al2O3 spheres, and the catalysts exhibited a typical mesoporous structure. The study investigated the impact of Ru loading, catalyst quantity, catalyst reduction temperature, hydrogen production temperature, feeding rate, and concentrations of NaBH4 and NaOH on the rate of hydrogen production (HPR). The evaluation of hydrogen production revealed that the top-performing Ru/m-Al2O3 catalyst achieved a HPR of 22.44 L min–1 gRu–1 at 30 °C, with an apparent activation energy (Ea) of 33.98 kJ mol–1. The catalyst could continuously produce hydrogen for 1700 min with a 20 % decrease in activity. The characterization results before and after hydrogen production revealed that Ru/m-Al2O3 exhibited excellent structural stability after a prolonged period of hydrogen production, with no apparent changes in its morphology, crystal structure, Ru particle size, and pore structure. In addition, the X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), and hydrogen production performance results showed that the flow system could effectively prevent the aggregation of NaBO2 on the catalyst's surface, thereby significantly improving the hydrogen production activity.

Combustion Synthesis of Ag Nanoparticles and Their Performance During NaBH4 Hydrolysis

AbstractDue to their tremendous industrial, environmental, and biological applications, research focusing on the synthesis and applications of silver nanoparticles (Ag NPs) has attracted increased interest from researchers over the past two decades. Their structural as well as textural properties can be easily tuned depending on the synthesis protocol utilized. Combustion synthesis has received increased attention as a one-pot route for the synthesis of a wide spectrum of nanomaterials. In this study, we present the results of synthesizing Ag NPs employing urea as a combustion fuel. The effect of the temperature of calcination on the formation and structural features of Ag NPs has been checked over the 400–700 °C temperature range. The characterization of the synthesized Ag NPs has been performed using XRD, SEM, TEM, and XPS techniques. It was found that Ag NPs, with a crystallite size of 40 nm, start to form at around 400 °C. Conducting the calcination at the 500–700 °C range results in the persistence of the obtained Ag NPs. Moreover, the obtained nanomaterials are characterized by a membrane-like morphology. The activity performance of the synthesized Ag NPs was examined for the hydrolysis of sodium borohydride (NaBH4) over a temperature range of 35–50 °C. Increasing the calcination temperature has led to a decrease in the activity of the Ag NPs during the NaBH4 hydrolysis. Graphical Abstract

Fe3O4@SA MNCs Synthesis, Characterization, and First-time Use in Hydrogen Production by NaBH4 Hydrolysis

Hydrogen is a clean energy carrier that will reduce dependence on fossil fuels and contribute to reducing the harmful effects on the environment resulting from using fossil fuels. Hydrogen is produced by the hydrolysis of sodium borohydride (NaBH4), one of the chemical hydrides, using a catalyst. In this study, Fe3O4@Salicylic acid magnetic nano-catalyst (Fe3O4@SA MNCs) was synthesized using the co-precipitation technique. The structural, physical, and chemical properties of the produced Fe3O4@SA MNCs were characterized by FT-IR, XRD, VSM, SEM, and SEM-EDX methods. At room temperature, the effect on hydrogen production performance was examined in the amounts of Fe3O4@SA MNCs (10, 25, 50, 75, and 100 mg), NaOH (0, 10, 20, and 25 mg), and NaBH4 (25, 50, 100, 150 and 200 mg). The highest hydrogen generation rates (HGR) were obtained using 10 mg Fe3O4@SA MNCs, 150 mg NaBH4, and 0 mg NaOH at room temperature. The obtained HGR value was calculated as 400 mL gcat-1.min-1. Fe3O4@SA MNCs were used for hydrogen production for the first time in this study. This study showed that Fe3O4@SA MNCs exhibit catalytic properties and are a promising, efficient catalyst in hydrogen production from NaBH4.

Highly Active and Robust Catalyst: Co2B-Fe2B Heterostructural Nanosheets with Abundant Defects for Hydrogen Production.

A high-performance and reusable nonnoble metal catalyst for catalyzing sodium borohydride (NaBH4) hydrolysis to generate H2 is heralded as a nuclear material for the fast-growing hydrogen economy. Boron vacancy serves as a flexible defect site that can effectively regulate the catalytic hydrolysis performance. Herein, we construct a uniformly dispersed and boron vacancy-rich nonnoble metal Co2B-Fe2B catalyst via the hard template method. The optimized Co2B-Fe2B exhibits superior performance toward NaBH4 hydrolysis, with a high hydrogen generation rate (5315.8 mL min-1 gcatalyst-1), relatively low activation energy (35.4 kJ mol-1), and remarkable cycling stability, outperforming the majority of reported catalysts. Studies have shown that electron transfer from Fe2B to Co2B, as well as abundant boron defects, can effectively modulate the charge carrier concentration of Co2B-Fe2B catalysts. Density functional theory calculations confirm that the outer electron cloud density of Co2B is higher than that of Fe2B, among which Co2B with high electron cloud density can selectively adsorb BH4- ions, while the electron-deficient Fe2B is favorable for capturing H2O molecules, therefore synergistically promoting the catalytic NaBH4 hydrolysis to produce H2.

Reaction of NaBH4 and NaB(OH)4 as a way to increase the yield of hydrogen in catalytic hydrolysis of sodium borohydride by water

In this work, sodium tetrahydroxoborate (NaB(OH)4) that is the main product of the hydrolysis reaction of NaBH4 with a relatively small excess of water is studied in the reaction with sodium borohydride in the presence of a catalyst and without it. It was found, that mixtures consisting of NaB(OH)4 and NaBH4 begin to melt at 70 °C with the formation of a liquid phase without destroying the close coordination environment for both types of boron atoms. When a cobalt-based catalyst is added to mixtures, significant hydrogen evolution is observed. The resulting products are hydrogen and amorphous borates with a gross composition close to [NaBO2·0.75H2O].Carrying out the catalytic hydrolysis of borohydride in the system of initial composition H2O:NaBH4:catalyst under the conditions same to that the catalytic reaction of NaBH4 and NaB(OH)4 was observed is a promising way to produce H2 since it provides a high yield of hydrogen at small amounts of catalyst and atmospheric pressure. Catalytic hydrolysis carried out in the temperature range 80–120 °C with initial molar ratios H2O:NaBH4 = 3 and 2.7, and atmospheric pressure demonstrates a hydrogen yield of 8.3 wt% and NaBH4 conversion of 96 % at only 2.3 wt% of CoCl2 as catalyst. Since the resulting final composition of borates is close to [NaBO2·0.66H2O], the potential mass yield of hydrogen in this process can reach 9.3 wt%.

The mechanism and challenges of cobalt-boron-based catalysts in the hydrolysis of sodium borohydride

Among boron compounds, NaBH4 has emerged as a prominent candidate for hydrogen energy sources owing to its environmentally friendly characteristics and a high hydrogen content of up to 10.6 wt%.

Cobalt Organic Framework Supported over Carbon-Based Materials as Novel Catalysts in the Hydrolysis of Sodium Borohydride

It is no secret that the global supplies of fossil fuel resources have been steadily dwindling. While there is no consensus on when the reserves will be completely depleted, there has been an effort among scientists to find a new, sustainable energy source for the future. It is generally agreed that such a source needs to not only be abundant, but also avoid the harmful biproducts of current fuel sources. Some proposed energy sources include solar, wind, geothermal and more. While each of these sources have their benefits, they also have their drawbacks and the cost to install and maintain these sources, as well as the environmental damage done during their construction can offset their benefits. One potential new energy source can be found in hydrogen gas. Hydrogen is not only the most abundant element in the universe, but its gaseous form can be burned to produce only energy and water [1-12]. The biggest hurdle a hydrogen economy faces is in the storage of the highly combustible gas. An interesting method of storing hydrogen is via adsorption within the chemical structure of a molecule. Sodium borohydride (NaBH4) for example is a chemical that contains 10.8% hydrogen by weight and steadily releases hydrogen gas when mixed with water.1 In order to efficiently utilize this reaction a catalyst is required. Typical catalysts are often precious metals like platinum, gold, and palladium, which tend to be expensive to use. By forming these metals into nanoparticles, their surface area can be increased, which increases their catalytic potential, however, these nanoparticles have a tendency to agglomerate in solution. Previous work by this team explored the catalytic capability of these metals and notes the use of carbon-based support structures can mitigate this agglomeration.2-4 This study aims to expand on those studies by using cobalt nanoparticles, which is a more cost-effective metal. Two novel Cobalt terephthalate complexes were combined with graphene and multiwalled carbon nanotubes (MWCNT) respectively, then tested for their ability to catalyze the hydrolysis of sodium borohydride. These materials were characterized using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Powdered X-ray diffraction (P-XRD), and Fourier Transform Infrared spectroscopy (FTIR). It was observed that after a single reaction, our materials appeared to be converted into cobalt borohydrides. The hydrogen produced for each material was 73 mL and 76 mL for the graphene and MWCNT materials, respectively. This study provides a possible method for producing cheaper, cleaner energy for a more sustainable future.

EFFECTIVE POLYMER DECORATION ON NICKEL-IMINE COMPLEX TO ENHANCE CATALYTIC HYDROGEN EVOLUTION

Since fossil fuels are rapidly depleting, finding alternative energy sources is becoming increasingly important. Among these alternatives, hydrogen (H2) is the most viable option. In hydrogen evolution systems, supported metal catalysts enhance the catalytic activity in the hydrolysis reaction by increasing the surface area. Therefore, this research focuses on preparing three different polymer-decorated Nickel-Imine complex catalysts (Ni@EC, Ni@EC-250, Ni@ECM) to improve their efficiency. To achieve the catalysts, a Nickel-Imine complex [1] was supported on three different polymers (EC, EC-250, and ECM). The catalysts (Ni@EC, Ni@EC-250, Ni@ECM) were then utilized to generate hydrogen from NaBH4 hydrolysis. The hydrogen evolution rates for Ni@EC, Ni@EC-250, and Ni@ECM catalysts were found as 6879; 15576; 8830 and 15459; 28689; 23417 mL H2 gcat-1.min-1, respectively at 30 oC and 50 oC. Results indicate that the Ni@EC-250 catalyst exhibited the best activity. Consequently, the subsequent steps of the catalytic hydrolysis reaction were studied using Ni@EC-250. The activation energy of the Ni@EC-250 catalyst was estimated at 39.255 kJ.mol-1. The reusability tests demonstrate that Ni@EC-250 remains active in sodium borohydride hydrolysis even after five runs. Technical abbreviations are defined upon first use. This study elucidates the reaction mechanism and kinetic data of catalytic sodium borohydride hydrolysis at various temperatures.

Enhancing NaBH4 regeneration using an Al-rich alloy

Onsite hydrogen generation by sodium borohydride hydrolysis resolves hydrogen energy supply system challenges. However, the spent-NaBH4 regeneration is still a problem in the closed loop of this irreversible reaction. As the by-product is the key to the problem, NaB(OH)4 is regarded as not the boron source but the hydrogen source of NaBH4 regeneration. Therefore, in this study, inexpensive Al metal and NaB(OH)4 are ball milled under argon to regenerate NaBH4 without additional hydrogen input. However, the ball-milling reaction is hindered by the flexible Al and impact oxide layer, and the NaBH4 yield is only approximately 22 %. Therefore, a brittle intermetallic compound Mg2Al3 is reacted with NaB(OH)4 by ball milling, achieving a NaBH4 yield of over 42 %. The mechanism study shows that the brittleness of the raw material plays an important role in promoting the ball-milling reaction. This study achieves NaBH4 regeneration using only Al as the reducing agent and provides a promising method to promote the mechanochemical regeneration of NaBH4.

Nickel/nickel oxide nanocomposite particles dispersed on carbon quantum dot from caffeine for hydrogen release by sodium borohydride hydrolysis: Performance and mechanism

The political and economic problems caused by the limited use of fossil fuels are another important reason that leads people to alternative energy sources. Compared to other energy sources, hydrogen has the potential to be the energy source of the future. In this study, the preparation of Ni/NiO doped caffeine-based carbon dot(CCQD) for efficient hydrogen (H2) production from the hydrolysis of sodium borohydride (NaBH4) is included the fabrication of nanoscale caffeine-based carbon quantum dot, the preparation of the CCQD-supported Ni/NiO catalyst as boron-free and the preparation of the CCQD-supported Ni/NiO catalyst by hydrothermal treatment in ethanol solvent (NiO@ CCQD-HT (EtOH)). The HGR values obtained with NiO@CCQD-HT (EtOH) was 16,819 ml min−1gcat−1. Moreover, the turnover frequency (TOF) value for the NiO@CCQD-HT (EtOH) was found as 2315 h−1. The activation energy (Ea) for the NiO@CCQD-HT (EtOH) catalyst was 39.48 kJmol−1.

MOF‐Templated Hierarchical Porous Hollow Core‐Shell Framework Cobalt Oxide for Enhancing Hydrogen Generation from Borohydride‐Based Hydrolysis

AbstractDesigning and fabricating a competent cobalt‐based catalyst for sodium borohydride (NaBH4) hydrolysis is of great importance. The present work reports the synthesis of hierarchical porous hollow core‐shell framework cobalt oxide (HCSCO) via etching and calcination processes, which is then employed for catalyzing NaBH4 hydrolysis. The surface morphology and the hollow core‐shell framework of HCSCO were revealed by scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses; the crystalline structure and the formation of Co3O4 in HCSCO were determined by X‐ray diffraction (XRD) and Raman spectroscopy; the surface area and porosity of HCSCO were verified by N2 adsorption‐desorption isotherm; and X‐ray photoelectron spectroscopy (XPS) was utilized to examine the chemical states of HCSCO. The as‐prepared HCSCO showed prominent catalytic hydrolysis of NaBH4 to generate H2 with a H2 generation rate of 441 ml min−1 gcatalyst−1 and a low activation energy (Ea) of 34.8 kJ mol−1. This Ea value of HCSCO is substantially lower than that of other catalysts, including noble metal catalysts or composites reported in the literature. Besides, HCSCO could remain its superb activity (~100 % H2 generation efficiency) over multiple hydrolysis cycles without significant changes of morphology and microstructure. The catalytic hydrolysis mechanism for H2 generation from NaBH4 using HCSCO is also proposed. This work provides a valuable strategy for the synthesis and fabrication of state‐of‐art catalysts for H2 generation from the hydrolysis of NaBH4.

Catalytic Hydrolysis of Sodium Borohydride

Catalytic Hydrolysis of Sodium Borohydride

Potential of nickel oxide catalyst from banana peel extract via green synthesis method in both photocatalytic reduction of methylene blue and generation of hydrogen from sodium borohydride hydrolysis

In the present work, nickel oxide (NiO) catalyst was prepared using banana peel extract as a stabilizing agent via the green synthesis method. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultraviolet spectroscopy (UV) analyses were carried out to investigate the structural and textural characteristics of the NiO catalyst. According to the XRD and TEM results, the particle size of the NiO catalyst was found to be in the range of 20–80 nm. From the EDX analysis, it was concluded that the NiO catalyst was synthesised in pure form. The potential of the NiO catalyst was tested for the first time in both the photocatalytic reduction of methylene blue (MB) and the generation of hydrogen (H2) from sodium borohydride (NaBH4) hydrolysis. A high decolorization efficiency of 98.09 % and a reuse efficiency of 90.89 % after five recycles were achieved for the photocatalytic reduction of MB using NiO catalyst. The photocatalytic reduction of MB was consistent with the pseudo-first order kinetic model, and the reaction rate constant was found to be 2.55 min−1. The H2 generation rate (RH2) of 922.5 mLH2 min−1 gcat−1 at 70 °C was achieved for the NaBH4 hydrolysis. The kinetics of H2 generation from NaBH4 hydrolysis was studied employing the nth-order and the Langmuir-Hinshelwood models, and the activation energy (Ea) values were found to be 21.29 kJ mol−1 and 22.23 kJ mol−1, respectively. It was concluded that the NiO catalyst prepared by the eco-friendly green synthesis method has a promising potential in both photocatalytic reduction of MB and H2 generation from NaBH4 hydrolysis.