Nanocomposite Catalyst Research Articles

Design of MgO/graphene nanocomposites for photocatalytic reduction of 4-nitrophenol and electrocatalytic oxidation of Methylene blue dye

The present study deals with the combustion synthesis of MgO/Graphene (MG) nanocomposites and investigates their photocatalytic, electrocatalytic, and photo-electrocatalytic properties for efficient redox reactions. Techniques such as FT-IR, XRD, SEM, HR-TEM, EDX, BET, and UV–vis-DRS were used to characterize MG nanocomposites. Both the photocatalytic degradation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) and the electrocatalytic results of the MG2 nanocomposite were studied under visible light. The results showed that the MG2 nanocomposite catalyst achieved 99.07% degradation of MB dye and kinetic degradation rates of 0.114 min−1 after 40 min, compared to the catalytic activity of MG0. Thus, facile modification can effectively improve the photocatalytic reduction (toxic 4-NP to beneficial 4-AP) and electrocatalytic degradation (MB) abilities of MG0. The functions of active species in the catalytic process were investigated using various scavengers. The ·OH radicals are the reactive species responsible for the 4-NP reduction, and a possible mechanism for improved catalytic activities was also provided. Incorporating graphene under visible light boosted the MG’s activity and confirmed it to be the most effective method for handling MB dye.

Efficient degradation of Enrofloxacin with novel magnetic MnFe2O4/NiS2 composite as an activator of peroxymonosulfate

The development of highly active and recoverable heterogeneous catalysts for peroxymonosulfate (PMS) activation to remove the persistent presence of antibiotics in aquatic environments, such as Enrofloxacin (ENR), remains a significant challenge. Here, we introduce a pioneering magnetic nanocomposite catalyst, MnFe2O4-NiS2, synthesized via a two-step hydrothermal process, which activates PMS to efficiently degrade ENR. The optimized 0.25MnFe2O4-NiS2/PMS system reached an ENR removal efficiency of 89.9 % within 90 min, outperforming both NiS2/PMS and MnFe2O4/PMS by 5.6 and 2.5 times, respectively. Quenching experiments and electron spin response analysis confirmed SO4•- and •O2– as the primary reactive oxygen species. The enhanced mediated electron transfer capability of the 0.25MnFe2O4-NiS2 nanocomposite improved the redox cycling of Ni (Ⅱ), Mn (Ⅱ) and Fe (Ⅲ) on its surface, as verified by Density Functional Theory calculations. Furthermore, the activation of surface PMS complexes (PMS*) played a crucial role in ENR degradation. The proposed degradation pathways of ENR were confirmed, and toxicity analysis indicated a decrease in intermediate toxicity with the 0.25MnFe2O4-NiS2/PMS system. This study presents an innovative magnetically recoverable, multifunctional catalyst with easy reusability for potential applications in the degradation of organic pollutants.

Molybdenum-doping to enhance the deprotonation ability of nickel-based hydroxide electrocatalysts for ethanol oxidation

With technological advancements, the practical application of ethanol oxidation reaction (EOR) is becoming increasingly promising, yet the need for higher ethanol concentrations highlights the growing importance of the deprotonation ability (Ni2+ to Ni3+) of the catalyst. The deprotonation ability is the key step for nickel-based catalysts in EOR, as it is essential for Ni2+ to continuously undergo deprotonation to transform into Ni3+ in order to maintain the continuous EOR. Herein, we developed Mo-doped Ni(OH)2 nanosheets by a hydrothermal method. The Mo-doped Ni(OH)2 nanosheets show excellent EOR performance due to the high valence doping of Mo, the onset potential of the oxidation peak (Ni2+ to Ni3+) appears at a position with a small overpotential,. The in-situ Raman spectroscopy technique further characterized the increase in NiOOH in the process of EOR. The Mo-doped Ni(OH)2 nanocomposite catalyst facilitates the oxidation of Ni2+ into Ni3+. Based on the above theoretical guidance, Mo-doped Fe/Ni(OH)2 nanosheets was designed and synthesized. The outstanding EOR performance of the Mo-Fe/Ni(OH)2-3 showed a potential of 1.352 V at 10 mA cm−2. The catalyst was used to design three-electrode reversible zinc-ethanol-air battery (T-RZEAB), which effectively overcomes the opposing kinetic and thermodynamic requirements for EOR and oxygen reduction reaction (ORR) catalysts in the oxygen electrode. The charging voltage of T-RZEAB with Mo-Fe/Ni(OH)2-3 is 240 mV lower than that of a traditional zinc-air battery at 25 mA cm−2.

Hierarchical core-shell ZIF-11@ZIF-8 composite nanocatalyst for high-yield simultaneous transesterification-esterifications of sunflower oil to produce biodiesel

Decreasing the mass transfer resistance is a promising technique to prepare an efficient catalyst for improving biomass macromolecules conversion in biodiesel production. In this study, hierarchical core–shell composite nanocatalysts were prepared through a solvothermal technique using zeolitic imidazolate framework-8 (ZIF-8) and ZIF-11 metal–organic frameworks (MOFs). The nanocatalysts were characterized by XRD, FT-IR, BET, FE-SEM, EDS, XPS, TEM, NH3-TPD, and CO2-TPD analyses. The results showed high crystallinity, high surface area (1446.86 m2/g), high pore volume (0.65 cm3 g−1), and mesoscale pore size (2.37 nm). Furthermore, TEM images confirmed the formation of core–shell structure for the composites. The catalytic activity was evaluated in the transesterification of sunflower oil at different operating conditions. The highest biodiesel yield (96.4 %) and full free fatty acid (FFA) conversion were obtained over the ZIF-11@ZIF-8 nanocatalyst at the optimum operating conditions: 120 °C, catalyst concentration of 8 wt%, methanol to oil ratio of 40:1, and 10 h. The ZIF-11@ZIF-8 nanocatalyst showed high thermal and chemical stability after several sequence cycles, leading to high reusability.

Catalytic Application of Cs‐Substituted Phosphotungstic Acid (CsxH3‐xPW12O40)‐Mesoporous Zirconium Phosphate (m‐ZrP) Nanocomposite Towards Synthesis of Structurally Diverse Tetrazole Moieties

AbstractThe rational design of a high surface area heterogeneous nanocomposite catalyst with well‐defined surface acidic sites and structural porosity is a promising approach with potential application in expeditious synthesis of biologically active molecules/scaffolds. In this work, mesoporous zirconium phosphate (m‐ZrP) was synthesized through a hydrothermal process and used as a porous matrix for dispersion of cesium‐exchanged phosphotungstic acid (CsxH3‐xPW12O40) nanoparticles to prepare CsxH3‐xPW12O40‐mZrP nanocomposite systems. Various characterization techniques, including XRD, UV–vis‐DRS, FTIR, FESEM, HRTEM, TGA‐DTA, BET, and TPD, were used to understand the structural, morphological, and surface properties of the composites. XRD analysis revealed the presence of m‐ZrP and cubic CsxH3‐xPW12O40 crystalline phases in the nanocomposite materials. A microscopic study indicated the existence of rod‐shaped morphology that was formed by the coalescence of a large number of spherical nanoparticles with diameters between 150 and 200 nm. The dispersion of CsxH3‐xPW12O40 over the m‐ZrP surface results in significant enhancement of medium and strong acidic sites, with the maximum number of acidic sites observed for the Cs0.5‐PTA‐mZrP composite (0.406 mmol g−1). The catalytic activity of the CsxH3‐xPW12O40‐mZrP nanocomposites was evaluated for rapid synthesis of tetrazole derivatives through [3 + 2] cycloaddition reactions of substituted nitrile and NaN3 under mild conditions. The detailed optimization study revealed that the use of Cs0.5‐PTA‐mZrP catalyst in DMF media afforded 90% yield of the tetrazole at 120 °C. Reaction kinetics study suggested that the optimal Cs0.5‐PTA‐mZrP catalyst exhibited the highest reaction rate of 2.06 × 10−3 mmol h−1m−2 towards tetrazole formation. Structurally diverse tetrazole derivatives in high yield and purity were synthesized under mild conditions using CsxH3‐xPW12O40‐mZrP nanocomposite as catalyst.

Synthesis of heterogeneous nanocomposite catalyst ZrO2@SBA-15 for formic acid production from hemicelluloses

Heterogeneous nanocomposite ZrO2@SBA-15 catalysts containing 10 wt. % of zirconium oxide were synthesized by two methods: co-condensation and incipient wetness impregnation. The silica support and catalysts were characterized by X-ray diffraction, gas adsorption, FTIR-spectroscopy and other physicochemical methods. As a result of zirconia introduction into the silica wall, the mesostructured of SBA-15 is preserved, but the specific surface area and pore Volume are reduced. It was established that during one-stage co-condensation synthesis, the particle fibers shorten and stick together. The catalysts were tested in the process of catalytic hydrolysis-oxidation of hemicelluloses of aspen wood. The optimal formic acid synthesis conditions were determined: 150°С, 3 h. The highest formic acid yield obtained over the catalyst obtained by co-condensation under best reaction conditions was 28.4 wt. %.

CNT@Ti3C2TxMXene Nanocomposite Catalysts as Anodes to Improve the Electricity Production Performance of Microbial Fuel Cells

CNT@Ti3C2TxMXene Nanocomposite Catalysts as Anodes to Improve the Electricity Production Performance of Microbial Fuel Cells

Zeolite Crystallization Inside Chemically Recyclable Ordered Nanoporous Co3O4 Scaffold: Precise Replication and Accelerated Crystallization.

The synthesis of mesoporous zeolites has garnered attention with regard to improving their catalytic and adsorption performances. While the hard-templating method provides opportunities to design precisely controlled hierarchical micro- and mesoporous structures, synthesizing mesoporous zeolites without external precipitation requires significant work. This is mainly due to the absence of usable templates other than carbon with hydrophobic surfaces. Herein, it is demonstrated that the Co3O4 template is valuable in preparing mesoporous silicalite-1 and ZSM-5 with a precisely controlled porous structure through hydrothermal synthesis. Unlike conventional carbon templates, the Co3O4 template is relatively hydrophilic, effective in suppressing external precipitation, and is reusable by dissolving in an acidic solution. The crystallization process also differs from that of the carbon template, as the silicate precipitates on a 3D ordered nanoporous Co3O4 scaffold, followed by crystallization and crystal growth. Furthermore, it is unexpectedly observed that the zeolite crystallization is accelerated in the Co3O4 template. The synthetic approach utilizing nanoporous metal oxides opens new doors for the control of the hierarchical structure of zeolites, as well as for the design of metal oxide-zeolite nanocomposite catalysts, due to the potential extensibility of the combination of metal oxides and zeolites.

Confined synthesis of ultrafine NiCu nanoalloy anchored nanoflower derived from natural attapulgite for efficient catalytic hydrogenation of p-nitrophenol

Improving the performance of catalysts through precise microstructural design is important for their applications. Herein, a series of nanoflower-shaped NiCu nanoalloy/nickel-copper silicate (NiCuSi)/attapulgite (ATP) nanocomposite catalysts was successfully constructed. Initially, the NiCuSi/ATP substrates were prepared using Ni2+ and Cu2+ ions to induce the epitaxial growth of acid-leached ATP. Afterwards, the domain-limited Ni2+ and Cu2+ ions in the silicon framework of NiCuSi were transformed to ultra-small NiCu nanoalloy particles (∼5.71 nm) through an in-situ reduction process. Due to the unique morphology and structure, the catalyst exhibited a specific surface area of up to 227.05 m2/g, which exposed abundant active sites to contact with the reactant molecules. The uniformly dispersed ultra-small NiCu nanoalloys effectively promoted the rapid transfer of interface electrons, resulting in excellent catalytic efficiency of the catalyst. Its catalytic reduction rate for PNP is as high as 0.374 s−1, equivalent to those of the precious metal catalysts, and the excellent catalytic efficiency remains at 98.53 % even after 10 cycles. This study provides a universal and efficient method to develop highly active and stably nanocomposite catalysts from natural and green carries.

Novel and reusable magnetic MOF nanocomposite coupled ionic liquid- promoted efficient chemical fixation of CO2 into α-alkylidene cyclic carbonates

Carbon dioxide as a C1 building block to synthesize α-alkylidene cyclic carbonates is an environmental and sustainable approach. In this work, we designed and synthesized a type of multifunctional magnetic MOF nanocomposite catalysts, which could realize the carboxylic cyclization of CO2 and propargylic alcohols into α-alkylidene cyclic carbonates under solvent-free conditions. Among all the prepared nanocomposites, the MnFe2O4@SiO2@Cu-MOF nanocomposite is the best in catalytic activity combined with the tetrabutylphosphonium acetate ([Bu4P]OAc) ionic liquid cocatalyst. The catalytic system MnFe2O4@SiO2@Cu-MOF/[Bu4P]OAc displayed excellent performance in catalyzing the carboxylic cyclization of CO2 and different propargylic alcohols, and a series of α-alkylidene cyclic carbonates were obtained in high to excellent yields (88 ∼ 98 %) under mild reaction conditions (0.2 MPa, 35 °C). In addition, the two-component catalytic system had high stability and reusability, and can be easily separated and reused up to six consecutive cycles without considerable decrease in catalytic activity. Moreover, using the ionic liquid [Bu4P]OAc as the cocatalyst, the nanocomposite had good substrate adaptability for the catalytic carboxylic cyclization, which opens interesting prospects for the development of new magnetic MOF nanocomposites as efficient heterogeneous catalysts for the chemical transformation of CO2 into value-added chemicals.

Synthesis of Au/Ce2S3@CeO2/CuS nanocomposites for promoted catalytic performance in propargylamine conversion

A newly developed nanocomposite catalyst, Au/Ce2S3@CeO2/CuS, has been engineered for effective propargylamine synthesis through the A3 coupling reaction. The catalyst’s synthesis involved the targeted addition of 15 wt% CeO2 to the CuS sulfur precursor, leading to the formation of a Ce2S3 layer due to its lower solubility product constant (Ksp). This layer, along with 0.5 wt% Au nanoparticles, significantly increased the Ce3+ concentration (16.9 % to 33 %∼52 %), which can accelerate the Cu+/Cu2+ valence state changes, thereby promoting the activation of the alkynyl hydrogen to enhance propargylamine formation. After 2 h reaction, the Au/Ce2S3@CeO2/CuS catalyst achieved over 99 % conversion, nearly 55 % more than pure CuS (45.5 %). The Au/Ce2S3@CeO2/CuS nanocomposite also showed excellent recyclability (80 % retention after 5 cycles) and a high conversion rate of 222.5 mmol·g−1·h−1.

Bi3TiNbO9/Bi2S3 Heterojunction for Efficient Photosynthesis of H2O2 in Pure Water

AbstractHeterojunction engineering has been deemed one of the most promising strategies for promoting charge separation and improving solar‐to‐chemicals efficiency. Howbeit, constructing well‐defined nanoheterojunction with superior photocatalytic activity for H2O2 generation and a clear reaction mechanism remains a formidable challenge. Herein, an in situ vulcanization way to synthesize an intriguing 2D/1D Bi3TiNbO9/Bi2S3 heterojunction by growing Bi2S3 nanorods on Bi3TiNbO9 microsheet is used for the first time, where an S‐scheme charge transfer mechanism is formed that facilitates the spatial separation of charge carriers. Moreover, the in situ grown Bi2S3 on Bi3TiNbO9 can optimize the interfacial electronic structure and the reaction energy barriers. As a result, the H2O2 yield rate for Bi3TiNbO9/Bi2S3 can reach 810(2) µmol g−1 h−1 without any sacrificial agents and cocatalysts, ≈6.18 and ≈18.0 times of pristine Bi3TiNbO9 and Bi2S3, respectively. Importantly, the heterojunction unveiled unprecedented stability, remaining ≈95.46(2)% of the initial one after 13 continuous cycles. This work highlights an innovative in situ vulcanization strategy to engineer oxide perovskite/metal sulfide nanocomposite catalysts for artificial photosynthesis of H2O2, opening new opportunities for achieving highly efficient photocatalyst systems.

MOF-Derived Ni/NiO-C Nanocomposites as Bifunctional Electrocatalysts Capable of Driving Both ORR and OER.

Bifunctional electrocatalysts, capable of efficiently driving both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), are crucial for advancing electrochemical processes. While noble-metal-based catalysts are widely recognized for their role in oxygen processes, current state-of-the-art designs are limited to either ORR or OER activity, presenting a notable research gap. In addressing this challenge, we have developed a novel Ni/NiO-C nanocomposite catalyst derived from a nickel-based metal-organic framework (Ni-SKU-5). For the ORR, the Ni/NiO-C catalyst exhibits an onset potential of 0.95 V vs RHE in a 1.0 M KOH solution, coupled with a Tafel slope of -99 mV dec-1 at 1600 rpm. Moreover, the catalyst displays excellent stability, maintaining a performance of over 90% after 10 h of continuous reaction. Furthermore, the catalyst proves effective in the OER, boasting an overpotential of 370 mV (at 10 mA cm-2) and a Tafel slope of 114 mV dec-1, highlighting its bifunctionality. The bifunctional overpotential of the Ni/NiO-C composite is measured at 820 mV, surpassing that of the 20% Pt/C electrocatalyst (860 mV), highlighting its potential for practical applications. Comparative experiments establish the origin of the robust bifunctional reactivity toward the conformal hybrid structure, porous framework, and the synergistic effect operating among the constituents of the nanocomposite.

Design a well-dispersed Ag-based/CoFe2O4–CNT catalyst for hydrogen production via NaBH4 hydrolysis

Green hydrogen is a crucial element in the hydrogen value chain, encompassing hydrogen production, transportation, storage, and application. The production of green hydrogen via NaBH4 hydrolysis (SBH) entails a high cost. However, the fast kinetics of this process with a catalyst compensate for the substantial cost, especially in specific applications, such as local or intermittent use. Silver is known for its excellent catalytic properties. Its high catalytic activity is a key factor in achieving efficient hydrogen generation from (SBH). In this study, a nanocomposite catalyst composed of silver nanoparticles (AgNPs), CoFe2O4, and carbon nanotubes (CNT) was investigated to demonstrate an effective catalyst design approach to achieve enhanced hydrogen generation performance. The H2 production rate in the presence of Ag-based/CoFe2O4–CNT was 320 mL min−1 g−1, and the apparent activation energy was 14.7 kJ mol−1, superior to that of Ag-based catalysts reported in the literature. Analyses of the observed outcomes revealed that the CNT was decorated with well-dispersed AgNPs and CoFe2O4 nanoparticles. The synergistic effects of AgNPs, CoFe2O4, and CNT were demonstrated by analyzing the kinetic behaviour of each component based on systematic comparisons. Furthermore, the paramagnetic property of CoFe2O4 enables harvesting of the catalyst using an external magnetic field, and it was verified that the reactivity of the collected catalyst was maintained throughout seven successive cycles. The outstanding catalytic performance of Ag/CoFe2O4–CNT should be attributed to the uniform dispersion of nanoparticles on the CNT surface. Furthermore, our key approach for developing efficient Ag-based carbon advanced catalysts for SBH in the future is to ensure their suitability for industrial applications.

Effectively enhanced photocatalytic hydrogen production performance of novel noble metal-free Cu(OH)2/MoSe2-g-C3N4 ternary nanocomposite under visible light irradiation

The present work presents a novel copper hydroxide-molybdenum diselenide-carbon nitride (3 % Cu(OH)2/MoSe2-g-C3N4, (3CM-CN)) ternary nanocomposite catalyst. This catalyst was synthesized using a three-step process: hydrothermal synthesis, ball milling, and wet impregnation. The focus of this research is on the hydrogen generation (H₂) capabilities of this novel material. The catalyst was extensively characterized using various analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible (UV–Vis) spectroscopy, photoluminescence (PL) spectroscopy, and X-ray photoelectron spectroscopy (XPS), resulting in a comprehensive understanding of its structure, morphology, optical properties, and surface composition. The catalytic activity and mechanism of Cu(OH)2/MoSe2-g-C3N4 composites were investigated. The ternary nanocomposite catalyst significantly enhanced hydrogen production, achieving rates 7.7 times greater than g-C3N4 and 4 times greater than 3 % Cu(OH)2/MoSe2 (3CM). Its maximum production reached an impressive 3012 µmol g−1 h−1. The analysis demonstrated a significant increase in active sites on the composite’s surface, accompanied by an increase in the composite-specific surface area to 73 m2/g. The development of a ternary nanocomposite led to a higher rate of catalyst production for hydrogen generation while simultaneously decreasing the rate of electron-hole recombination. It gave an innovative strategy for constructing highly efficient composite catalysts for hydrogen generation very effectively.

Reduced graphene oxide-Fe3O4-TiO2 nanocomposite catalyst for the mineralization of herbicide dalapon by heterogeneous photoelectro-Fenton process

Fast degradation and complete mineralization of herbicide dalapon (DPN) as the target pollutant has been investigated for the first time by the heterogeneous photoelectro-Fenton (hPEF) process using a nitrogen doped reduced graphene oxide (NrGO) modified carbon felt (CF) cathode (NrGO@CF) and a ternary nanocomposite catalyst (TNC) based on reduced graphene oxide (rGO), Fe3O4, and TiO2 to maintain high yield generation of H2O2 and •OH. The effects of main variables, including the catalyst composition and amount, applied current, and initial pH of the solution, were investigated. The as-synthesized nanomaterials exhibit significant improvements thanks to their high specific surface area, increased H2O2 production, catalytic activity, and the possibility to work in a wide pH range. This system also promotes photoreduction and photooxidation reactions by increasing photon absorption. By combining highly conductive carbon materials and the photoexcited electrons from TiO2, redox cycling between ≡FeII and ≡FeIII was facilitated, thus improving the process performance. Catalytic stability measurements show that the use of a NrGO@CF cathode, an equimass rGO-Fe3O4-TiO2 TNC and boron doped diamond (BDD) anode trio resulted in the fast degradation and complete mineralization of DPN within 30 and 60 minutes, respectively, after five consecutive cycles under UV light irradiation, 500 mA current intensity, 0.1 g L−1 catalyst concentration and pH 6 conditions. Moreover, intermediate products of DPN oxidation were identified. Therefore, this study highlights an efficient and stable cathode and catalyst duo for the removal of a short chain halogenated aliphatic herbicide from aqueous media.

Review on polyaniline-based nanocomposite heterogeneous catalysts for catalytic reduction of hazardous water pollutants.

Water contamination by highly toxic substances has generated serious ecological disturbances and health problems for humans. Hence, decontamination of toxic pollutants using advanced, inexpensive, and eco-friendly approaches is the current demand. Heterogeneous catalyst-based catalytic reduction processes have offered the opportunity to transform hazardous water pollutants into non-hazardous products via sustainable, eco-friendly, and efficient routes and might be a competitive substitute for existing traditional water purification techniques. However, the key challenges linked with pure heterogeneous catalysts include agglomeration and poor dispersion, stability, recovery, and reusability, which result in poor activity and efficiency. Thus, it is essential to produce multipurpose polymer-based composite catalysts using conducting polymers, which are exceptionally good supportive and matrix materials. The blending of metal-based nanomaterials with polyaniline conducting polymers produces highly stable and efficient heterogeneous nanocomposite catalysts with amazing catalytic activity against a wide range of water pollutants. The heterogeneous catalytic reductive degradation of immensely toxic pollutant water has gained substantial curiosity because of its excellent physicochemical and surface characteristics, porous structure, recoverability, and recyclability. Therefore, this review presents the latest efforts to generate various polyaniline-based nanocomposite catalysts using a polyaniline matrix and various nanofiller materials and their potential applications in heterogeneous catalytic reduction degradation of water pollutants.

Phosphotungstic Acid-Supported Hercynite: A Magnetic Nanocomposite Catalyst for the Selective Esterification of Chloroacetic Acid.

This study presents the synthesis and characterization of a novel phosphotungstic acid-functionalized hercynite@SiO2 magnetic core-shell through a three-step procedure. The characterization involved various analyses including Fourier-transform infrared spectroscopy, P-XRD, TGA-DSC, EDAX, inductively coupled plasma optical emission spectroscopy, elemental mapping, scanning electron microscopy, transmission electron microscopy, and value stream mapping. The catalytic performance of the hercynite@SiO2-PTA nanomagnetic composite was examined in the esterification of chloroacetic acid. Results indicate that the developed procedure enables the production of chloroacetic acid esters using a wide range of primary, secondary, and tertiary aliphatic and aromatic alcohols with good to excellent yields and high selectivity. The significance of this work lies in its straightforward synthesis method, minimal time requirement, reduced utilization of hazardous chemicals, and cost-effectiveness. Additionally, the catalyst exhibited magnetic recyclability for up to five cycles with negligible loss in activity. Notably, the synthesized catalyst demonstrated nontoxicity and environmental friendliness.

Insights into the in-situ generation of singlet oxygen via molecular oxygen activation over NiO@CuxO NRs/CF nanocomposite catalysts: Mechanisms of singlet oxygen evolution and chloroquine phosphate degradation

Herein, we fabricated a novel NiO@CuxO nanorods (NRs) composite electrode grown in-situ on copper foam (CF), designated as NiO@CuxO NRs/CF. This electrode demonstrates excellent performance in a heterogeneous electro-Fenton-like system. It efficiently activates O2 to generate 1O2 in-situ without the addition of oxidant precursors and effectively degrades chloroquine phosphate (CQ). The combination of NiO and CuxO nanoarrays created multiple synergistic sites for molecular oxygen adsorption and activation. The addition of NiO induced the formation of low-valence Cu species and effectively optimized oxygen reduction reaction (ORR) kinetics. This enhancement led to an increased generation of key intermediates (·O2– and ·OH), which further promoted the efficient production of 1O2 through the chain reaction mediated by ·O2– and ·OH. NiO@CuxO NRs/CF achieved a 3.9-fold increase in 1O2 production compared to the CF electrode. NiO@CuxO NRs/CF electrodes exhibited exceptional performance in degrading CQ across a wide pH range (3-11). Meanwhile, it also displayed remarkable stability and anti-interference capability, highlighting their promising potential for practical applications. The study provides an innovative strategy for the in-situ production of 1O2 through molecular oxygen activation with a bimetallic composite catalyst to efficiently degrade organic pollutants.

Silica-supported Bi2O3[sbnd]Cr2O3 nanocomposite: Efficient catalyst for Pyrano[3,2-c]chromenes synthesis and DFT studies

Synthesis of a new nanocomposite catalyst, consisting of Bi and Cr loaded on silica (Bi2O3Cr2O3@SiO2), is achieved using the incipient wetness impregnation approach. This catalyst is used to synthesize Dihydropyrano[3,2-c]chromene scaffold via one-pot reaction method involves the mixture of 4-Hydroxycoumarin, Malononitrile or Ethyl cyanoacetate and different aromatic aldehydes in methanol at room temperature. The catalyst was characterized using several methods such as XRD, FT-IR, FE-SEM, and EDS. The efficacy of this heterogeneous catalyst Bi2O3Cr2O3@SiO2 was evaluated by loading different wt% of bismuth and chromium on silica. The wt% of Bi2O3Cr2O3 (2.5–1) on SiO2 was proven to be extremely suitable catalytic activity to get high yield of products (up to 98 %) in short span of time (up to 15 min) with high selectivity as outlined in the proposed mechanism. Additionally, density functional theory (DFT) studies of the Dihydropyrano[3,2-c]chromenes were conducted to elucidate their electronic properties and reactivity. It provided insights into the frontier molecular orbitals, electrostatic potential maps of these synthesized compounds, offering valuable information for future rational design of related Chromene-based molecules. The catalyst was successfully recovered and reused for up to five reaction cycles without any significant decline in its catalytic efficiency. Future work will focus on expanding the use of this catalyst for synthesizing library of bioactive compounds.