Catalytic Reduction Of 4-nitrophenol Research Articles

Green-synthesized BiFeO3 nanoparticles for efficient photocatalytic degradation of organic dyes, antibiotic and catalytic reduction of 4-nitrophenol

Green-synthesized nanoparticles have recently emerged as promising catalysts for the removal of toxic dyes from water bodies. In this article, Bismuth ferrite nanoparticles were synthesized by a simple and low-cost method using Couroupita guianensis plant leaf extract. The particles were used as photocatalysts for degrading RhB, MO dyes, and TC antibiotics, as well as for reducing toxic 4-NP to useful 4-AP. The synthesized nanoparticles were characterized using several state-of-the-art tools. The formation of perovskite structure and the presence of biomolecules on the surface of BiFeO3 nanoparticles were confirmed by FTIR analysis. Raman spectrum revealed a rhombohedral structure of BiFeO3 nanoparticles, corroborating the XRD findings. FESEM micrograph demonstrated irregularly shaped agglomerated nanoparticles. The average hydrodynamic diameter was estimated to be 51 nm using the DLS technique. The optical energy bandgap of the bismuth ferrite was estimated using Tauc’s relation for direct bandgap semiconductors. SQUID measurements revealed that these nanoparticles exhibit a weak ferromagnetic ordering. Furthermore, these nanomaterials degraded the cationic and anionic dyes effectively because of the formation of hydroxyl radicals, confirmed by the scavenger test. The photocatalytic degradation pathway of RhB dye was investigated through LC-MS analysis, and the intermediate degradation products were identified. The prepared material also exhibited excellent catalytic reduction efficiency in a short duration of time. This study proclaims that these nanoparticles can be used as potential catalysts for the purification of water bodies.

Multifunctional Au–Ag NCs for luminescence and colorimetric double signal sensing of H2S and catalytic reduction of nitrophenol

In this study, the N-Acetyl-l-Cysteine (NAC)-capped gold and silver bimetallic nanoclusters (NAC@Au–Ag NCs) was synthesized by reflux method. Due to the silver effect, the NAC@Au–Ag NCs exhibited strong photoluminescence at far-red/near-infrared regions and better catalytic performance than Au or Ag NCs. Upon addition of H2S, the Au–Ag NCs exhibited obvious fluorescence quench and color changes through the generation of metal sulfides and a static quenching process. The Au–Ag NCs displayed a wide linear luminescence response for H2S (18.5–217 μmol/L) with a detection limit of 0.269 μmol/L. Moreover, the visible color of Au–Ag NCs changed from white to brown-yellow along with increased H2S, the corresponding RGB values also displayed good linearity with the concentration of H2S (90.1–678 μmol/L). Notably, the fabrication of test strips provided a convenient and intuitive tool to screen the freshness of eggs by the color change of test strips. Au–Ag NCs could be used for living HeLa cells bioimaging and recognition of H2S abnormalities. Furthermore, it can be used as a catalyst to reduction of nitrophenols (NPhs), specific included 2NP, 3NP and 4NP. The reaction was regarded as a pseudo-first-order kinetic reaction due to the presence of excess NaBH4. At 298K, the catalytic rate constants(k) of 2NP, 3NP and 4NP were 0.1754 min−1, 0.1734 min−1 and 0.2782 min−1, respectively. The NAC@Au–Ag NCs catalyst still showed good catalytic activity and reusability after five cycles. Therefore, this study developed a H2S sensor for food samples and biological systems. And this nanocatalyst had great application potential for removed the nitrophenol pollutants in water.

The Contradicting Influences of Silica and Titania Supports on the Properties of Au0 Nanoparticles as Catalysts for Reductions by Borohydride

This study investigates the significant impact of metal–support interactions on catalytic reaction mechanisms at the interface of oxide-supported metal nanoparticles. The distinct and contrasting effects of SiO2 and TiO2 supports on reaction dynamics using NaBD4 were studied and focused on the relative yields of [HD]/[H2] and [D2]/[H2]. The findings show a consistent increase in HD yields with rising [BD4-] concentrations. Notably, the sequence of HD yield enhancement follows the order of TiO2-Au0-NPs < Au0-NPs < SiO2-Au0-NPs. Conversely, the rate of H2 evolution during BH4- hydrolysis exhibits an inverse trend, with TiO2-Au0-NPs outperforming the others, followed by Au0-NPs and SiO2-Au0-NPs, demonstrating the opposing effects exerted by the TiO2 and SiO2 supports on the catalytic processes. Further, the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) confirms the catalytic mechanism, with TiO2-Au0-NPs demonstrating superior activity. The catalytic activity observed aligns with the order of TiO2-Au0-NPs > Au0-NPs > SiO2-Au0-NPs, suggesting that SiO2 donates electrons to Au0-NPs, while TiO2 withdraws them. It is of interest to note that two very different processes, that clearly proceed via different mechanisms, are affected similarly by the supports. This study reveals that the choice of support material influences catalytic activity, impacting overall yield and efficiency. These findings underscore the importance of selecting appropriate support materials for tailored catalytic outcomes.

Thiocarbohydrazide-cross-linked pectin: A promising support material for palladium nanoparticles in the water-mediated Suzuki-Miyaura cross-coupling reaction and the catalytic reduction of 4-nitrophenol

Suzuki-Miyaura reaction is a classic palladium-catalyzed reaction for forming Csp2-Csp2 bonds. However, the leaching of Pd species and using organic solvents are two important problems that adversely affect their performance, reusability, and greenness. Considering the abundant resources, cheapness, and availability of pectin (Pec), a Pec-based catalyst for the Suzuki reaction in pure water as a non-toxic reaction medium was developed for the first time. In this regard, Pec was chosen as a benign support and cross-linked by thiocarbohydrazide (TCH) to prepare Pec-TCH. The Pec-TCH acted as an efficient reducing and stabilizing agent for in-situ fabrication of Pd(0) nanoparticles. The heterogeneous and air-stable Pec-TCH-Pd(0) nanoparticles were thoroughly characterized. The results exhibited a significant catalytic activity (up to 99%) and reusability (at least 7 times) for in-water Suzuki-Miyaura cross-coupling reaction. The use of TBAB as a phase-transfer catalyst improved the yield of Suzuki reaction since it prevented the problems related to the immiscibility of water and aryl halides as well as the gelation of catalyst. The catalyst was also utilized for water-mediated 4-nitrophenol reduction to 4-aminophenol with NaBH4 which showed excellent activity (k = 9.2 × 10−3 s−1). A very good compatibility with iodobenzene, bromobenzene, and chlorobenzene was observed for the Suzuki reaction. Because of various binding sites such as amino, hydroxyl, carbonyl and thiocarbonyl groups, negligible leach of Pd nanoparticles was observed, as shown by ICP-MS after runing 7th of reusability studies. Moreover, the leaching, mercury poisoning, and large-scale tests showed its potential for industrial applications.

Synthesis and catalytic activity of core-shell gold-palladium nanoworms towards the catalytic reduction of 4-nitrophenol and methyl orange

The Au-Pd core–shell nanostructures have gained attention as a promising catalyst and exhibit outstanding stability and selectivity in pivotal chemical reactions. This work demonstrates a facile seed-mediated approach for depositing the shell of Pd on worm-shaped Au nanostructures. The control over Pd content on Au nanoworms (NWs) was achieved by adjusting the concentration of tetrachloropalladic acid (H2PdCl4) in the deposition solution. The bent morphology, surface roughness, and polycrystalline structure of the Au NWs ensured that at lower H2PdCl4 concentrations, Pd formed an island-like structure on the Au NWs’ surface. In contrast, increasing the H2PdCl4 concentration led to the formation of a complete Pd shell encasing the Au NWs. The catalytic activity of the Au-Pd core–shell (Pd@Au) NWs exhibited a significant improvement compared to uncoated Au NWs, which has been attributed to the synergetic effect of the two metals. However, it was observed that an optimum Pd-coating was necessary to obtain the best catalytic performance and a further increase in Pd content led to the degradation of the catalytic activity. Specifically, the rate constant of the reduction reactions of 4-nitrophenol (4-NP) and methyl orange (MO) was increased by 6.3 and 3.1 folds, respectively, for the optimized Pd@Au NWs.

Remarkable Enhancement of Catalytic Reduction of Nitrophenol Isomers by Decoration of Ni Nanosheets with Cu Species.

Herein, the catalytic reduction of isomers of nitrophenols (NPS) using Ni x Cu y nanostructures with different molar ratios is presented. Ni x Cu y catalysts are prepared using star-shaped Ni nanoparticles as seeds. The applied synthesis transforms Ni nanoparticles into sheet-like structures when Cu species are deposited on them. The bimetallic sheet-like Ni x Cu y nanostructures demonstrate high catalytic activity to reduce NP isomers concerning their monometallic counterparts. The contribution of the Cu+ species affects the catalytic reduction of the NPS isomers. For example, the catalytic reduction of 4-nitrophenol (4-NP) depends on the Ni:Cu molar ratio: Ni1.75Cu > Cu > NiCu > Ni7Cu > Ni3.5Cu > Ni. The Ni7Cu catalyst exhibits the highest catalytic activity in the reduction of nitrophenol isomers 2-nitrophenol (2-NP) and 3-nitrophenol (3-NP), and the obtained results are comparable with those reported for noble-metal-based catalysts. The low-cost production of Ni x Cu y catalysts and their high catalytic stability and availability make them attractive for industrial applications.

Multiplicative rGO/Cu-BDC MOF for 4-nitrophenol reduction and supercapacitor applications

Two-dimensional nanosheets, with their distinct characteristics, are widely used in various applications such as water splitting, supercapacitors, catalysis etc. In this research, we produced Cu-BDC MOF nanosheets by using Cu2O nanotubes for metal ions and H2BDC as the organic linker. We combined these Cu-BDC MOF nanosheets with reduced graphene oxide (rGO) to form a nanocomposite. The collaboration between Cu-BDC MOF and rGO boosts both the catalytic reduction of 4-nitrophenol and the electrochemical capabilities. The conversion of 4-nitrophenol to 4-aminophenol is achieved using sodium borohydride as both a reducing agent and a catalyst. The study explores the impact of different concentrations of 4-nitrophenol and sodium borohydride on catalytic efficiency. The increase in sodium borohydride concentration enhances catalytic efficiency by providing more BH4− ions and electrons for the reduction process. The catalytic reduction process adheres to the Langmuir–Hinshelwood mechanism with apparent pseudo-first-order kinetics. Specifically, Cu-BDC MOF and rGO/Cu-BDC MOF exhibit specific capacities of 468.4 mA h/g and 656.4 mA h/g at a current density of 2 A/g, respectively, while also enhancing the operating voltage window. Therefore, electrodes based on rGO/Cu-BDC MOF nanosheets present a novel approach for environmental remediation and energy storage applications across various fields.

Catalytic Reduction of 4-Nitrophenol and Methylene Blue with Silver Nanoparticles Decorated with Drymoglossum piloselloides Extract

Drymoglossum piloselloides is one of the epiphytic plants that is commonly found in Southeast Asia region. In this study, the ethanol extract of D. piloselloides plant has been used in the green synthesis of silver nanoparticles. The synthesized silver nanoparticles were characterized by ultraviolet-visible (UV-Vis) spectrophotometry, X-ray diffraction (XRD),Fourier-transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM) measurements. The UV-Vis spectrum of silver nanoparticles showed a maximum wavelength at 453 nm. The XRD measurement showed the silver nanoparticles peaks at 38.38°, 44.60°, 64.76°, and 77.62°. The FTIR spectra provided evidence of the interaction between silver and chemicals in the plant extract as a weak signal at 682 cm-1. Meanwhile, TEM revealed an average size of 12.63nm. The synthesised silver nanoparticles were utilised for the reduction of 4-nitrophenol with a conversion percentage of up to 100% with a reduction reaction rate constant of 7.104 s-1. In addition, methylene blue was also successfully reduced with the synthesised silver nanoparticles as the catalyst with a reduction reaction rate constant (k) of 21.150 s-1. This study highlights the superior advantage of utilizing ethanolic extract of D. piloselloides to prepare silver nanoparticles with promising catalytic reduction purposes.

Metal-organic frameworks (MOFs) wrapped palladium nanoparticles-loaded Fe3O4@CFR core-shell magnetic nanohybrid as heterogeneous catalyst with robust catalytic properties

Metal-organic frameworks (MOFs) wrapped palladium nanoparticles supported on Fe3O4@catechol formaldehyde resin (Fe3O4@CFR@Pd@MOF) as magnetic nanohybrid catalyst was successfully fabricated by employing the redox capacity of CFR shell of Fe3O4@CFR core-shell microsphere for in situ formation of Pd NPs, followed by surface coating with Cu-MOF(HKUST-1). The research results demonstrated that the complementary properties of the various components within this hybrid material yielded magnetic recyclable nanocatalysts with exceptional catalytic performance. The Fe3O4@CFR@Pd@MOF catalyst exhibited remarkable advantages in the catalytic reduction of nitrophenol, demonstrating a transformation frequency (TOF) value of up to 4651 h−1. Additionally, the nanocatalyst was proved to have robust catalytic capacity in the reduction of organic dyes and Suzuki-Miyaura reaction. The HKUST-1 framework played a triple role: facilitating dye enrichment, Cu2+ assisting Pd NPs catalysis, and mitigating Pd NPs leaching. Moreover, the synthesized catalyst exhibited favorable magnetic properties, enabling facile separation by magnets for efficient recycling and reutilization.

Carbonized cellulose microspheres loaded with Pd NPs as catalyst in p-nitrophenol reduction and Suzuki-Miyaura coupling reaction

Catalytic reduction of p-nitrophenol is usually carried out using transition metal nanoparticles such as gold, palladium, silver, and copper, especially palladium nanoparticles (Pd NPs), which are characterized by fast reaction rate, high turnover frequency, good selectivity, and high yield. However, the aggregation and precipitation of the metals lead to the decomposition of the catalyst, which results in a significant reduction of the catalytic activity. Therefore, the preparation of homogeneous stabilized palladium nanoparticles catalysts has been widely studied. Stabilized palladium nanoparticles mainly use synthetic polymers. Cellulose microspheres, as a natural polymer material with low-cost and porous fiber network structure, are excellent carriers for stabilizing metal nanoparticles. Cellulose microspheres impregnated with palladium metal nanoparticles were carbonized to have a larger specific surface area and highly dispersed palladium nanoparticles, which exhibited excellent catalytic activity in the catalytic reduction of p-nitrophenol. In this work, the cellulose carbon-based microspheres palladium (Pd@CCM) catalysts were designed and characterized by SEM, TEM, EDS, XRD, FTIR, XPS, TGA, BET, and so on. Furthermore, the catalytic performance of Pd@CCM catalysts was investigated via p-nitrophenol reduction, which showed high catalytic activity. This catalyst also exhibited excellent catalytic performance in the Suzuki-Miyaura coupling reaction. Linking aromatic monomer and benzene through Suzuki-Miyaura coupling was presented as an effective route to obtaining biaryls, and the synthesis method is low-cost and simple. In addition, Pd@CCM showed desirable recyclability while maintaining its catalytic activity even after five recycles. This work is highly suggestive of the design and application of the heterogeneous catalyst.

Biosynthesis of CuFe2O4@Ag hybrid nanocomposite: Ultrasensitive detection and catalytic reduction of 4-nitrophenol

Due to the dearth of extremely capable, sensitive, and stable catalysts, the efficient detection and catalytic removal of 4-nitrophenol (4-NP) in industrial wastewater remains a serious challenge. The detection and determination of 4-nitrophenol (4-NP) presence in the environment is a matter of paramount importance because it is a high-priority hazardous pollutant that can affect people, animals, and plants. Here, we present a promising and economically viable green synthetic route for fabricating CuFe2O4 and CuFe2O4@Ag hybrid nanocomposites from the leaf extract of Senna didymobotrya. The UV–Vis, FTIR, XRD, FE-SEM, EDXA, BET and VSM analysis were performed to characterize the synthesis of CuFe2O4@Ag nanocomposite. To evaluate the electrocatalytic capacity of CuFe2O4@Ag, electrochemical sensing stratergy was performed with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The modified CuFe2O4@Ag glassy carbon electrode (GCE) (CuFe2O4@Ag/GCE) demonstrated a linear response in the range of 0.01-15 μg/ml (71 nm-107 μM) and the ability to detect 4-NP at low concentration (0.006 μg/ml (43 nM)). Due to the increased surface area of CuFe2O4@Ag/GCE by ̴ 1.5-fold, a greater cathodic current response (-16 μA/cm2) at a low potential of -0.81 V was observed compared to CuFe2O4/GCE alone for the detection of 4-NP. Additonally, CuFe2O4@Ag showed excellent reduction ability towards 4-NP using NaBH4 with an efficiency of 96.4 % which was higher than the CuFe2O4 (only 87.3 %) in 12 min due to the synergistic relationship among Ag NPs and CuFe2O4 nanostructures. The outcomes from this study shows that the bi-functional electrocatalyst holds vast potential for environmental remediation.

Surface Deposition of Magnesium Ferrite-Based Supports with Bimetallic Gold/Silver Nanoparticles for the Catalytic Reduction of Nitroaromatics.

Surface deposition of magnesium ferrite nanoparticles (MgFe2O4 NPs) with bimetallic gold/silver (Au/Ag) nanoparticles was conducted using the seed-mediated growth method to obtain magnetic-metallic composite catalysts for use in the catalytic reduction of nitroaromatics. Two types of amine-functionalized MgFe2O4 and MgFe2O4@SiO2 NPs were used as magnetic supports for the surface deposition process. The combination of several characterization analyses (i.e., XRD, XPS, TEM, SEM, EDS, and VSM) confirmed the successful syntheses of the MgFe2O4/Au/Ag and MgFe2O4@SiO2/Au/Ag NPs. The catalytic reduction of 4-nitrophenol using sodium borohydride as a reducing agent revealed that the reaction was completed within 2 min by using MgFe2O4/Au/Ag and MgFe2O4@SiO2/Au/Ag NPs as catalysts. The appearance rate constant of the MgFe2O4/Au/Ag NPs was slightly higher than that of the MgFe2O4@SiO2/Au/Ag NPs. In terms of reusability, high conversion (>80%) of the reduction of 4-nitrophenol was still obtained after 7 and 10 consecutive cycles for the MgFe2O4/Au/Ag and MgFe2O4@SiO2/Au/Ag catalysts, respectively. Interestingly, these two catalysts exhibited the highly catalytic conversion of the chosen nitroaromatic derivatives (i.e., 4-nitrobenzaldehyde and 4-nitroaniline). On the whole, the MgFe2O4/Au/Ag and MgFe2O4@SiO2/Au/Ag NPs could be utilized as suitable and sustainable catalysts for the catalytic reduction of nitroaromatics due to several desirable features (i.e., high activity, facile and rapid separation by a magnet, and good reusability).

Crystal plane effect of copper with different oxides/hydroxides nano-composites on catalytic performance and mechanism towards the reduction of 4-nitrophenol

Here, four copper oxide/hydroxide composites Cu/CuO, Cu-Cu2O/Fe2O3, Cu-CuO/Co(OH)2, and Co(OH)2/CuO with CuO(111) or Cu(111) as the central exposed crystal plane were synthesized and used in the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). A study of the dynamic changes of reaction was carried out by real-time HPLC-Q-Orbitrap-HRMS/MS, HPLC, UV–Vis detection, and DFT simulation. It revealed that in copper based catalytic reduction of 4-NP, three different reaction mechanisms are generated over four catalysts. The different adsorption modes and higher adsorption strength of 4-NP on the CuO(111) and Cu(111) plane make it selective and active for both direct hydrogenation and condensation in the reduction of 4-NP. The synergistic effect of different metal crystal faces with CuO(111) can improve the catalytic activity, especially the CuO(111)/Co(OH)(011) crystal planes that have the best synergistic effect on the reduction of 4-NP. This work reports an example where the reaction mechanism was significantly affected by the principal exposed crystal planes of copper oxide/hydroxide composites. It can be very informative for understanding the catalytic processes and providing new ideas for the design of novel catalysts.

A comprehensive review on biogenic synthesis of bimetallic nanoparticles and their application as catalytic reduction of 4-nitrophenol

A comprehensive review on biogenic synthesis of bimetallic nanoparticles and their application as catalytic reduction of 4-nitrophenol

Efficient Removal and Recovery of Ag from Wastewater Using Charged Polystyrene-Polydopamine Nanocoatings and Their Sustainable Catalytic Application in 4-Nitrophenol Reduction.

This study addresses the long-standing challenges of removing and recovering trace silver (Ag) ions from wastewater while promoting their sustainable catalysis utilization. We innovatively developed a composite material by combining charged sulfonated polystyrene (PS) with a PDA coating. This composite serves a dual purpose: effectively removing and recovering trace Ag+ from wastewater and enabling reused Ag for sustainable applications, particularly in the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The PS-PDA demonstrated exceptional selectivity to trace Ag+ recycling, which is equal to 14 times greater than the commercial ion exchanger. We emphasize the distinct roles of different charged functional groups in Ag+ removal and catalytic reduction performance. The negatively charged SO3H groups exhibited the remarkable ability to rapidly enrich trace Ag ions from wastewater, with a capacity 2-3 times higher than that of positively-N+(CH3)3Cl and netural-CH2Cl-modified composites; this resulted in an impressive 96% conversion of 4-NP to 4-AP within just 25 min. The fixed-bed application further confirmed the effective treatment capacity of approximately 4400 L of water per kilogram of adsorbent, while maintaining an extremely low effluent Ag+ concentration of less than 0.1 mg/L. XPS investigations provided valuable insights into the conversion of Ag+ ions into metallic Ag through the enticement of negatively charged SO3H groups and the in situ reduction facilitated by PDA. This breakthrough not only facilitates the efficient extraction of Ag from wastewater but also paves the way for its environmentally responsible utilization in catalytic reactions.

Plant axillary stem gall extract mediated bioengineered CuO nanoprisms as robust and reusable catalyst for photocatalytic and catalytic degradation of water pollutants

The current work explains the synthesis of bioengineered CuO nanoprisms using axillary stem gall extract of the Ziziphus mauritiana plant. The photocatalytic and catalytic reduction potential of bioengineered CuO nanoprisms was analyzed for the photo-mineralization of methylene blue (MB) organic dye under exposure to visible light and catalytic reduction of 4-nitrophenol (4-NP) in the presence of NaBH4 solution. The biogenic CuO nanoprisms were characterized using XRD, FTIR, FESEM, EDS, and UV–Vis. spectroscopic techniques. The mean crystallite size of CuO nanoprisms was estimated to be 34.24 nm while the band gap energy value was found to be 1.47 eV. 99.21 % of MB dye was photo-mineralized within 70 min of visible light illumination at pH=5 and 30 mg of catalyst whereas 4-NP was almost completely reduced to 4-AP within 5 min in the presence of bioengineered CuO (NPs). The data of photo-mineralization of MB dye and catalytic reduction of 4-NP well agreed to the pseudo-first-order kinetics with the rate constant values of 63.86 × 10−3 and 0.8439 min−1, respectively. The reactive species entrapping studies revealed that •OH radicals were the key active species affianced in the photo-mineralization of MB dye. Photostability and reusability tests established that only a 9 % decline in the dye degradation efficiency of bioengineered CuO was observed after the fifth cycle of reuse under visible light irradiation.

Synergistic effect of copper and nickel oxides from MOF-74 precursors for enhanced catalytic reduction of p-nitrophenol

Catalytic reduction stands out as a promising approach for wastewater treatment due to its inherent simplicity, mild reaction conditions, and high efficiency. In this work, Cu/Ni-MOF-74 precursors with different Cu2+/Ni2+ ratios were prepared by hydrothermal method and calcined them at 400 °C for 2 h to obtain the corresponding CuO/NiO composite catalysts. The experimental results showed that the catalytic reduction of 4-Nitrophenol (4-NP) by CuO/NiO was significantly stronger than that of CuO and NiO separately. Remarkably, the best CuO/NiO-1 catalytic reduction of 4-NP exhibits the pseudo-first-order kinetic constant k of 0.28 min−1 and the mass normalization constant km of 56 min−1 mg−1. Compared with CuO and NiO, the prepared CuO/NiO-1 composite catalyst with a large specific surface area can provide more active sites for the adsorption and diffusion of 4-NP. Notably, this catalytic reaction mechanism aligned with the Langmuir-Hinshelwood model. Theoretical investigations further elucidated that the synergistic interplay between CuO and NiO bolstered the adsorption of H species and 4-NP, while also aiding in product desorption. This study not only presents a novel approach for designing and synthesizing highly active catalysts for 4-NP but also lays the groundwork for future advancements in this field.

FeCx-coated biochar nanosheets as efficient bifunctional catalyst for electrochemical detection and reduction of 4-nitrophenol

Herein, we present the exceptional performance of FeCx-coated carbon sheets (FC) derived from the pyrolysis of waste biomass as a bifunctional catalyst for electrochemical detection and catalytic reduction of 4-nitrophenol (4-NP). Despite having a lower surface area, larger particle size, and lesser N content, the FC material prepared at a calcination temperature of 900 °C (FC900) outperforms the other samples. Deeper investigations revealed that the FC900 efficiently facilitates the charge transfer process and enhances the diffusion rate of 4-NP, leading to increased surface coverage of 4-NP on the surface of FC900. Additionally, relatively weaker interactions between 4-NP and FC900 allow the facile adsorption and desorption of reaction intermediates. Due to the synergetic interplay of these factors, FC900 exhibited a linear response to changes in 4-NP concentration from 1 μM to 100 μM with a low limit of detection (LOD) of 84 nM (S/N = 3) and high sensitivity of 12.15 μA μM−1 cm−2. Importantly, it selectively detects 4-NP in the presence of five times more concentrated 2-aminophenol, 4-aminophenol, catechol, resorcinol, and hydroquinone and ten times more concentrated metal salts such as Na2SO4. NaNO3, KCl, CuCl2, and CaCl2. Moreover, FC900 can accurately detect micromolar levels of 4-NP in river water with high recovery values (99.8–103.5 %). In addition, FC900 exhibited outstanding catalytic activity in reducing 4-NP to 4-aminophenol (4-AP), achieving complete conversion within 8 min with a high-rate constant of 0.42 min−1. FC900 also shows high recyclability in six consecutive catalytic reactions due to Fe magnetic property.

Facile green synthesis of Phyllanthus emblica extract based Ag-NPs for antimicrobial and response surface methodology based catalytic reduction applications

Silver nanostructures were synthesized by utilizing facile and simple green methodology based on the usage of biogenic Phyllanthus emblica fruit extract. The Fourier transform infrared spectroscopy revealed that the numerous phytochemicals were found to be present in the extract that were responsible for reducing the precursor salt into nanoparticles. After 10 min, the silver nanoparticles were formed in the system while the further nucleation for 30 min resulted in the generation of the silver nanostructures with dual morphology (spherical & rod-like morphology). The reaction time/nucleation time was found to be the major factor responsible for the modulation of the morphology of the biogenic nanomaterials. The crystalline nature with the cubic crystal system was observed in the case of the silver nanostructure via X-ray diffraction analysis. The antimicrobial efficacy investigated for these nanostructures revealed that the silver nanostructures possess comparable or greater efficacy than the selected control. The excellent efficacy is attributed to the smaller size and the peculiar morphological characteristics of the silver nanostructures. The catalytic reduction of 4-nitrophenol via silver nanostructures was also investigated by using the response surface methodology as an optimization tool. An extremely high percentage reduction value of 96.491 % with the rate constant value of 0.277 min−1 was documented in the case of Ag-NSs. The prepared silver nanostructures were found to be extremely stable till six reuse cycles. Our findings affirm that the efficient synthesis of nanostructures is achieved by using P. emblica fruit extract and the synthesized material further presents excellent viability for antimicrobial and catalytic applications.

Novel, Biosynthesis of Palladium Nanoparticles using Strychnos Potatorum Polysaccharide as a Green sustainable approach; and their effective Catalytic Hydrogenation of 4-Nitrophenol

In the current study, we successfully used strychnos potatorum polysaccharide through autoclaving to synthesize palladium nanoparticles in a green, sustainable process. These polysaccharide act as a stabilizing, capping, and reducing agent. It also used various analytical characterizations, including UV–Visible spectroscopy, FT-IR spectroscopy, X-Ray diffraction (XRD), Scanning electron microscopy (FE-SEM), EDAX, and X-ray photoelectron spectroscopy (XPS), TEM and gel permeation chromatography (GPC) are used to analyze biosynthesized pallidum nanoparticles (PdNPs). The surface plasmon resonance (SPR) band at 276 nm and UV–visible spectroscopy revealed the presence of the generated PdNPs. The XRD data show that PdNPs have crystalline behavior and a pristine face-centered cubic (FCC) structure. The PdNPs were successfully developed by catalytic reduction of 4-nitrophenol (4-NP). The catalytic activity and reusability of the environmentally friendly PdNPs catalyst were demonstrated by achieving a remarkable transformation of 95 % nitrophenol to 4-aminophenol after five cycles. The reaction rate constant (k) for the degradation of 4-nitrophenol (4-NP) using SP-PdNPs as a catalyst is 0.1201 min−1 and R2 0.9867, with a normalized rate constant of (Knor = K/m) of 7.206 s−1 mM−1. These findings provide fundamental knowledge of the catalytic process governing the hydrogenation of p-nitrophenol, which will help designers of effective catalysts. An innovative and affordable technique for creating PdNPs that are environmentally acceptable and can be utilized as effective catalysts in environmental applications is the use of strychnos potatorum gum polysaccharide. The green-synthesized PdNPs can be used for pollutant remediation, including pharmaceutical, domestic, heavy metal, industrial, and pesticide pollutants.