Abstract
The present investigation aimed to assess the influence of the Co–W–B NPs catalyst on the process of sodium borohydride hydrolysis. The study involved the synthesis of Co–W–B NPs through the utilization of an eco-friendly green synthesis extract derived from the Rheum ribes shell in conjunction with the chemical reduction technique for catalyst production. The investigation of catalysts' structure and surface morphology was conducted through the utilization of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) techniques. The average particle size was determined to be 35 nm in TEM analysis. The presence of Co–W–B nanoparticles and their elemental composition % were determined through EDX analysis, revealing values of 63.9% (Co), 31.89% (C), 1.75% (B), and 2.46% (W) within the nanoparticle. The manufactured Co–W–B catalyst's use for hydrolysis of sodium borohydride was studied under various conditions, including different concentrations of NaOH and NaBH4, different amounts of catalyst, and different temperature parameters. The hydrogen production rate for the Co–W–B NPs catalyst in NaBH4 hydrolysis was determined to be 5367 mLg−1min−1 at 30 °C. The study involved the determination of TOF values for a catalyst composed of Co–W–B NPs, which were subjected to varying temperatures. The activation energies were determined through the utilization of the n-th order and Langmuir-Hinshelwood kinetic models and subsequently calculated using the Arrhenius equation, resulting in values of 35.36 and 31.70 kJ/mol, respectively. The values of enthalpy and entropy, ΔH and ΔS, were determined through the utilization of Eyring's equation, 18.49 kJ/mol and −80.7 J/mol.K, respectively.
| Original language | English |
|---|---|
| Pages (from-to) | 796-808 |
| Number of pages | 13 |
| Journal | International Journal of Hydrogen Energy |
| Volume | 51 |
| DOIs | |
| Publication status | Published - 2 Jan 2024 |
Bibliographical note
Publisher Copyright:© 2023 Hydrogen Energy Publications LLC
Funding
The Co–W–B catalyst was produced from Rheum ribes shell extract, and Fig. 1 shows morphological studies using standard scanning electron microscopy (SEM). Co–W–B catalysts demonstrate a spherical form and a foamy sponge-like structure with various particle sizes, as shown in Fig. 1 [37]. Furthermore, aggregation and twinning phenomena were also observed in the distribution of Co–W–B particle promoters, which means that the Co–W–B catalyst can expose a more active surface for catalytic hydrolysis of NaBH4. To better understand their morphology, TEM measurements were performed, and the corresponding micrographs are represented in Fig. 2. The TEM image of the Co–W–B catalyst showed particles with spherical shapes and the presence of a porous structure with a size of a few nanometers. Cobalt particles were represented by darker spots, while brighter sections of the extract were depicted by lighter dots. Cobalt was observed to settle into the support as tiny particles of different sizes (<4 nm), but small aggregations formed in some places. It supports the results of agglomerated SEM on TEM images. The observed agglomeration and the calculated average size of Co–W–B nanoparticles (∼35 nm) are consistent with previous reports [38]. Previous studies have stated that metals with W, Ni, Fe, and Cu doped to a Co–B catalyst have a smaller average particle size of ∼30 nm and a spherical structure [39,40].
Keywords
- Catalysis
- Green synthesis
- Nanoparticle
- Sodium borohydride
