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In this study, free-radical polymerisation inside MCM-41 mesopores was examined to expose a construction route for a temperature-responsive switchable polymer–silica nanohybrid material with well-defined porosity. Herein, we introduced a vinyl monomer (N-isopropyl acrylamide), a cross-linker, and an AIBN initiator into the palladium nanoparticle incorporated MCM-41 pore channels using the wet-impregnation method followed by in situ radical polymerisation. The structural properties of the synthesised PNIPAM–PdNP–MCM-41 catalyst were analysed by various sophisticated analytical techniques. The temperature switchable nanohybrid catalyst was used to reduce carbonyl compounds to their corresponding alcohols. The catalyst showed high catalytic efficiency and robustness in an aqueous medium at 25 °C. Moreover, the system's polymer layer remarkably boosted catalytic selectivity and activity for carbonyl compound reduction as compared to other controlled catalysts. The suggested switchable system can be employed as a temperature-controllable heterogeneous catalyst and highlights a substitute technique to counter the methodical insufficiency in switchable supported molecular catalytic system production.

Au Sn/ZnO nanocatalyst was synthesized by a two-step synthetic approach in which Au Sn alloy bimetallic nanoparticles (NPs) were incorporated into presynthesized ZnO in 1-butyl 3-methylimidazolium (BMIMBF4) ionic liquid (IL) via combustion route. The structure, morphology, and optical properties of the above synthesized material were analysed by using various analytical techniques, including X-Ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM), Energy Dispersive Spectroscopy Mapping (EDS), UV–vis Spectroscopy, Photoluminescence, Nitrogen Adsorption–Desorption, photoelectrochemical measurements and X-Ray Photoelectron Spectroscopy (XPS). The average particle size and the homogeneous distribution of Au Sn nanoparticle over the surface of ZnO was analyzed by using TEM. XPS analysis provides information regarding the elemental structure of individual species as well as the possible electronic interaction between the nanoparticles. The photocatalytic activity of the nanocatalyst was studied towards the degradation of organic contaminants such as rhodamine B dye, 2-chlorophenol, phenol, 2,4- dichlorophenol and 2,4-dinitrophenol. After 90 min the complete degradation of Rhodamine B (95%) and phenol (94%) and its derivatives was achieved under visible irradiation. The high photoactivity of 3Au 1Sn/ZnO can be attributed to the combined effect of enhanced light absorption intensity, longer lifetime of electron-hole pair, lower electron-hole recombination rate, increased stability, higher surface area and the synergistic effect between the metal nanoparticles and support material. It is expected that our current work could open promising prospects for the utilization of Sn-based bimetallic system as a potential visible light photocatalyst for environmental applications.

To develop a sustainable and cost-effective catalyst for cross-coupling reactions, dual (temperature and pH)-responsive poly(N-isopropyl acrylamide-co-methacrylic acid) (PNIPAM/PMAA) functionalised SBA-15 was synthesised via free radical polymerisation using potassium persulfate as an initiator and decorated with palladium nanoparticles (PdNPs-SBA-15-PNIPAM/PMAA). The X-ray photoelectron spectroscopic analysis revealed that the Pd content in the zero oxidation state of the catalyst was 1.21 wt%. The dynamic light scattering studies showed that the catalyst exhibited swelling behaviours at low temperatures ( 4), but exhibited deswelling behaviours at high temperatures (>32 °C) and low pH ( 90%) were realized for the room-temperature SMC reaction in an aqueous medium for various substituted aryl halides, while the conversion was low at relatively high temperatures (>32 °C). The conversion was dependent on the different electronic effects between the electron-releasing and electron-withdrawing groups of the aryl halides. After the experiment, the catalyst was successfully recovered without any loss of heterogeneity and could be reused at least up to the fifth cycle.

Phosphate functionalized graphene oxide (PGO), prepared by covalently bonding triethylphosphite on to the surface of graphene oxide (GO) via Arbuzov reaction has been demonstrated as an efficient catalyst for three component Biginelli condensation reaction with excellent yield (96%) under microwave condition. The PGO nanocatalyst was thoroughly characterized by Fourier transform infrared spectra (FTIR), FT-Raman spectroscopy, Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field-emission Scanning electron microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDS), N 2 adsorption/desorption study, Ammonia temperature-programmed desorption analysis (NH 3 -TPD) and Thermogravimetric analysis (TGA). The presence of acidic groups on PGO which play an important role in the catalytic transformation were measured by NH 3 -TPD analysis. Based on the catalytic results, a feasible catalytic mechanism has been proposed. Besides high catalytic activity, this nanocatalyst showed good recyclability, suggesting its potential applications for the synthesis of other important organic molecules.

Highly active and well defined Au-Cu nanoparticles supported on reduced graphene oxide (rGO) were synthesized by a simple and one-step deposition-precipitation method. The nanoparticles were thoroughly characterized by UV–vis, X-ray diffraction (XRD), High resolution transmission electron microscope (HRTEM), Scanning transmission electron microscope (STEM) with line scanning and line mapping energy dispersive X-ray spectroscopy (EDS), Raman and X-ray photoelectron spectroscopy (XPS). The composition dependant catalytic activity for the synthesized catalyst was evaluated in the reduction of 4-nitrophenol (4-NP). Among different metal and bimetallic Au-Cu compositions, Au3-Cu1 exhibited highest activity with rate constant of 96 × 10−3 s−1, which is superior to all other reported work. Within the density functional theory framework, theoretical investigations of our catalyst were carried out to find the reason behind its superior catalytic activity. It has been found that unique synergistic effect between the highly dispersed Au-Cu nanoparticles and rGO support helps in the efficient adsorption of 4-NP on Au3-Cu1/rGO catalyst, highlighting the importance of hybrid bimetallic nanoparticle-GO structure for enhanced catalytic activity. Moreover, effect of various support materials such as activated carbon and alumina was studied on the catalytic activity of Au-Cu nanoparticles. In addition, our catalyst demonstrated excellent activity for the reduction of toxic azo dyes (congo red, methyl orange, and erichrome black T), demonstrating its ability for multiple reduction reactions. Moreover, the efficient removal of the produced amines after the reduction reaction was demonstrated via a convenient waste management strategy using an industrial solid waste red mud. Our results will lead to the possibility of designing suitable GO-based bimetallic system with superior catalytic performance in environmental remediation applications.

A facile one-step combustion route is used for the synthesis of a magnetically separable GO–CuFe2O4–ZnO (GCZ) ternary nanocomposite photocatalyst with varying ZnO contents. Transmission electron microscope (TEM) observations show the exfoliation of graphene oxide sheets and decoration with well-dispersed ZnO and CuFe2O4 nanoparticles. The photocatalytic activity of the ternary nanocomposite was tested under solar light irradiation for the photodegradation of several dyes such as rhodamine-B (RhB), methylene blue (MB), methyl orange (MO), and neutral phenol. The evaluation results demonstrate that the ternary GCZ photocatalyst exhibits the best performance compared to GO–CuFe2O4 (GC), GO–ZnO (GZ), CuFe2O4, ZnO, and CuFe2O4–ZnO (CZ) photocatalysts towards the photocatalytic degradation of the dyes. Photoelectrochemical measurements were carried out to provide deep insights into the enhanced photocatalytic activity in the novel ternary nanocomposite. The improved photocatalytic activity of the ternary nanocomposite can be ascribed to the superior light assimilation, proficient charge transfer process, synergistic effects, high surface area, and superior durability of the composite. Furthermore, a possible reaction mechanism has been proposed. Our results have demonstrated that by precisely introducing GO with appropriate metal oxides, a highly efficient photocatalyst can be designed that would assimilate a wider range of visible light. Furthermore, CuFe2O4 nanoparticles themselves have excellent magnetic properties, which are largely maintained in the GCZ composite, and can be simply separated from the suspension system by applying a magnetic field.

The design of switchable hybrid systems to control the catalytic activity using stimuli-responsive polymers have a great significance in the precise manipulation of the oxidation reactions. Herein, we proposed a novel and facile approach for the synthesis of a dual-responsive silica nanohybrid catalyst by combining the temperature-responsive poly N-isopropylacrylamide (PNIPAM) and pH-responsive poly 4-vinylpyridine (P(4-VP)) with MCM-41 as integrated support via free radical polymerization. The prepared switchable material was decorated with silver nanoparticles (AgNPs) through the co-reduction approach. The X-ray photoelectron spectroscopy (XPS) data confirmed the existence of AgNPs in the zero oxidation state while the dynamic light scattering (DLS) measurements revealed that the material exists in maximum swelling confirmation at low temperature (

Graphene oxide as suitable support material was employed for the synthesis of GO-MnO2 nanocatalyst via a greener solution combustion route. Rod-like MnO2 was found to be uniformly adhered to both sides of graphene oxide (GO) sheets. The nanocatalyst was thoroughly characterized using different instrumental methods such as X-ray diffraction (XRD), N2 adsorption-desorption, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) with EDS mapping, UV–visible spectroscopy and Thermogravitometric (TG) analysis. From the experimental results, GO-MnO2 was found to be a potential catalyst for chalcones preparation via Claisen-Schmidt condensation. The catalytic activity of GO-MnO2 nanocatalyst was found to be superior as compared to pure MnO2 and GO. The reaction conditions were varied thoroughly by changing several reaction parameters like the solvent polarity, temperature, and catalyst wt%. High yield of chalcones was obtained in a short period of time at 110 °C under solventless conditions. The catalyst was easy to separate and was reused multiple times with minor change in activity. On comparing the activity with other reported catalyst in literatures it was revealed that GO-MnO2 nanocatalyst has significantly high activity in lesser period of time.

A novel graphene oxide (GO)–SnO2–TiO2-based ternary nanocomposite was prepared via a one-step solvothermal process. The structure, morphology, and optical properties were characterized by a series of techniques, including X-Ray Diffraction (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDS), UV-vis Diffuse Reflectance Spectroscopy (DRS), Photoluminescence, Raman spectroscopy, Nitrogen Adsorption–Desorption, and X-Ray Photoelectron Spectroscopy (XPS). Various microscopic images of the ternary nanocomposite showed that the SnO2 and TiO2 nanoparticles are firmly covered over GO, thereby increasing the surface area of the resultant nanocomposite. The photocatalytic activity of ternary GO–SnO2–TiO2 and binary GO–SnO2 and GO–TiO2 materials were studied through the photodegradation of congo red and methylene blue under solar radiation. The degradation efficiency of GO–SnO2–TiO2 was found to be 96% for methylene blue dyes within 60 min and 98% for congo red within 70 min, which is much higher than the binary composites. Furthermore, a photoelectrochemical study was performed to provide further insight into the photocatalytic activity, which further confirmed the superiority of the novel ternary nanocomposite in photocurrent generation. The enhanced photocatalytic properties of the ternary nanocomposite can be attributed to enhanced light absorption, efficient charge transfer process, high surface area, as well as superior durability of the composite. In addition, a possible reaction mechanism has been postulated. Our results have demonstrated that by carefully introducing GO with suitable metal oxides, highly efficient photocatalysts can be designed that would absorb a wider range of the solar spectrum.

Bimetallic nanoparticles, particularly those based on copper, have recently attracted a great deal of attention for the development of low cost and highly active catalysts due to the synergistic interaction between individual metal components. In this work, bimetallic Ag–Cu alloy nanoparticles were explored as a highly active and reusable catalyst for the enamination of 1,3-dicarbonyls using diverse amines. The nanocatalysts were intensively characterized by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy-energy-dispersive spectroscopy (HRTEM-EDS) and valence band and core level X-ray photoelectron spectroscopy (XPS) to study the effect of the bimetallic structure and composition. In comparison to monometallic Ag and Cu nanoparticles, the alloyed Ag–Cu nanoparticles showed a high catalytic performance and the resultant catalytic activity was dependant on the Ag to Cu ratio. This enhanced catalytic activity should be related to the electronic interaction between Ag and Cu nanoparticles formed due to the intimate contact between them. Our study may serve as a foundation for designing efficient alloyed nanocatalysts for fine chemical synthesis via enamination reactions.

A pH-responsive poly(methacrylic acid) (PMAA) functionalized SBA-15 nanohybrid has been synthesized via free radical polymerization method. Furthermore, silver nanoparticles (Ag NPs) were impregnated to the polymerized SBA-15-PMAA by using co-reduction approach. The resultant AgNPs-SBA-15-PMAA catalyst was used for the reduction of various dyes using NaBH4 as the reducing agent. Compared to all other synthesized catalysts in this work as well as with the existing catalyst in the literatures, our synthesized AgNPs-SBA-15-PMAA catalyst showed significantly higher activity for the reduction of dyes due to the synergistic effect of Ag NPs and pH responsive PMAA. The effects of reaction parameters such as pH, amount of nanoparticles, and NaBH4 concentrations were also studied in detail to obtain the optimized condition for the reaction. The overall catalytic performance showed that the reduction reaction is more efficient under low pH. In addition, the catalyst could be re-used without obvious losses of catalytic activity at least more than five cycles.

Functionalised mesoporous silica SBA-15 was designed to exhibit dual responsive behaviour by grafting poly [2- (N, N-dimethylamino) ethyl methacrylate] (PDMAEMA) via free radical polymerisation. For this, the SBA-15 was modified by 3-(trimethoxy silyl) propyl methacrylate (TMSPM) for allowing methacrylate functionality on the mesoporous surface for free radicle polymerisation (m-SBA-15). Temperature and pH responsive PDMAEMA were grafted on the well-ordered rod-like m-SBA-15. Monometallic palladium (Pd) nanoparticles (NPs) were then incorporated in the pre-synthesised m-SBA-15/PDMAEMA. The morphology and structure of resulting materials were characterised by powder X-ray diffraction, Fourier transform infrared spectroscopy, high resolution transmission electron microscopy, field emission scanning electron microscopy, thermogravimetric analysis, and nitrogen adsorption-desorption isotherms. The dual stimuli-responsive behaviour of the hybrid material was monitored by dynamic light scattering measurement. Synthesised materials were tested for their dual stimuli (pH and temperature)-responsive catalytic activity in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). It was observed that the catalytic activity of the Pd/m-SBA-15/PDMAEMA catalyst was significantly higher at a given pH and temperature than any of SBA-15 only without using PDMAEMA and Pd NPs, m-SBA-15 grafted with PDMAEMA without Pd NPs, or Pd NPs incorporated m-SBA-15 without grafting PDMAEMA.

MCM-41 was functionalized with thermoresponsive poly (N-isopropyl acrylamide) (p-NIPAM) by free radical polymerization. The surface of the p-NIPAM-coated on MCM-41 (MCM-41/p-NIPAM) nanocatalyst was decorated with bimetallic Ag–Pd nanoparticles for catalytic applications. The nanocatalyst was characterized by X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, nitrogen adsorption/desorption analysis, thermograviametric analysis (TGA), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray (EDX) spectroscopy, x-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS). The thermoresponsive behavior of the synthesized nanocatalyst was analyzed by UV–vis spectroscopy (UV–vis) and DLS analysis. The distribution of bimetallic nanoparticles and their compositions on the polymer-coated mesoporous silica surface were investigated by EDX mapping analysis. The specific surface area was characterized by nitrogen adsorption/desorption analysis. The nanocatalyst was tested for the catalytic reduction of benzaldehyde by UV–vis analysis. Interestingly, the bimetallic nanoparticle-supported MCM-41/p-NIPAM nanocatalyst showed higher activity compared to the other counterparts. In addition, the nanocatalyst showed thermoresponsive behavior at different temperatures and could be recycled for consecutive five cycles with minimal loss in activity. This study is expected to open promising probability for the use of the above material for a range of catalytic applications.

Ionic liquids (ILs) have attracted huge interest as templates for the fabrication of porous materials, as the possibility exists for the IL to act as both the solvent and porogen in such systems. Towards this objective, in this work, porous silica–graphene oxide nanocomposite(GO-SiO2) was synthesized using IL assisted solvothermal method. The N2 adsorption-desorption isotherm data showed that by using IL as a template highly mesoporous composite with higher surface area of 858 m2/g and average pore diameter of 5.3 nm can be obtained. Various other physiochemical properties of the nanocomposite were investigated by several sophisticated characterization techniques such as UV–Vis, FTIR, XRD, TGA, FESEM, HRTEM, XPS, and Raman spectroscopy. Later on, the synthesized GO-SiO2 nanocomposite was used as a versatile nanoadsorbent for Pb(II) and oxidized As(III) removal from water. Detailed adsorption mechanism was thoroughly studied via XPS. The effect of various parameters on adsorption such as pH, contact time, initial metal concentration and the nanoadsorbent amount was also investigated. The maximum adsorption capacities of our mesoporous nanocomposite towards Pb(II) and As(III) were found to be 527 mg/g and 30 mg/g, respectively. Kinetic studies indicated that the experimental details fit well with the pseudo-second-order kinetic model for both the adsorption process. It was also found that the Langmuir model was more suitable for Pb(II) adsorption whereas the Freundlich model was for oxidized As(III) adsorption. The thermodynamic parameters(ΔG 0, and ΔS > 0) indicate the adsorption process was endothermic in nature and spontaneous. The synthesized GO-SiO2 nanocomposite was reusable without any significant loss for 4 cycles.

In this research, mesoporous silica was synthesized via modified sol–gel technique using a series of 1-alky-3-methylimidazolium bromide [(CnMIM)Br (n = 4, 10, 16)], one kind of amphiphilic room temperature ionic liquids (RTILs), as a template. Subsequently, the material was characterized and identified by various techniques such as N2 adsorption–desorption isotherm, SEM, TGA and FT-IR analysis. To obtain the optimum condition, different variables such as adsorbent dose, contact time, initial concentration, temperature and pH were studied, and the optimum conditions were found to be 0.7 g/100 mL, 30 min, 10 mg L−1, 40 °C and pH of 6.0, respectively, for the adsorption of lead ions from aqueous solution. The results showed that the RTIL bearing longer alkyl chain 1-hexadecyl-3-methylimidazolium bromide [(C16MIM)Br] was a suitable adsorbent for Pb(II) removal among all the adsorbents. The adsorption of lead ions follows pseudo-second-order rate equation, and the equilibrium data fitted well with the Freundlich model with maximum adsorption capacity 5.18 mg g−1. Various thermodynamic parameters were calculated, and the results showed that the adsorption of lead ions on the material was feasible and endothermic in nature. The results from the adsorption–desorption cycles showed that the material held good desorption and reusability. It is concluded from the results that the material can be used to remove the Pb(II) from contaminated water to permissible limit.

A graphene oxide (GO)–SnO2-based nanocomposite was synthesized by decorating the graphene oxide surface with SnO2 nanoparticles via a solvothermal process. The nanocomposite was characterized using Fourier transform infrared spectra (FTIR), FT-Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field-emission Scanning electron microscopy (FE-SEM), Energy dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM) and N2 adsorption/desorption study. The FE-SEM and TEM images demonstrate the uniform distribution of the SnO2 nanoparticles on the GO surface and high-resolution transmission electron microscopy (HRTEM) confirms an average particle size of 8–12 nm. The GO–SnO2 nanocomposite has been found to be an extremely efficient catalyst for the synthesis of β-enaminones and β-enaminoesters in methanol solvent and also, in solventless conditions. The GO–SnO2 nanocomposites exhibited synergistically more superior catalytic efficiency compared to pure graphene oxide and SnO2 nanoparticles. The reaction conditions were optimized by changing different parameters such as catalyst, solvent, catalyst loading, and temperature. It has been found that the catalyst gave higher activity under solventless conditions than methanol. The GO–SnO2 composite was recycled for up to four cycles with minimal loss in activity.

A facile, efficient and environmentally-friendly protocol for the synthesis of xanthenes by graphene oxide based nanocomposite (GO-CuFe2O4) has been developed by one-pot condensation route. The nanocomposite was designed by decorating copper ferrite nanoparticles on graphene oxide (GO) surface via a solution combustion route without the use of template. The as-synthesized GO-CuFe2O4 composite was comprehensively characterized by XRD, FTIR, Raman, SEM, EDX, HRTEM with EDS mapping, XPS, N2 adsorption-desorption and ICP-OES techniques. This nanocomposite was then used in an operationally simple, cost effective, efficient and environmentally benign synthesis of 14H-dibenzo xanthene under solvent free condition. The present approach offers several advantages such as short reaction times, high yields, easy purification, a cleaner reaction, ease of recovery and reusability of the catalyst by a magnetic field. Based upon various controlled reaction results, a possible mechanism for xanthene synthesis over GO-CuFe2O4 catalyst was proposed. The superior catalytic activity of the GO-CuFe2O4 nanocomposite can be attributed to the synergistic interaction between GO and CuFe2O4 nanoparticles, high surface area and presence of small sized CuFe2O4 NPs. This versatile GO-CuFe2O4 nanocomposite synthesized via combustion method holds great promise for applications in wide range of industrially important catalytic reactions.

Advancement of an efficient and cost-effective method for heavy metal removal from contaminated water utilising Fe3O4–APTES–EDTA (FAE) nanocomposite, a productive reusable adsorbent, is explained in this study. The novel FAE nanocomposite was prepared and characterised using different techniques such as FTIR, XRD, TEM, EDS, BET, TGA, EDX and Zeta potential techniques. FAE is found to be a good adsorbent for Pb2+, Cd2+, Ni2+, Co2+ and Cu2+ removal with a higher adsorption capacity. The maximum adsorption capacity of Pb2+, Cd2+, Ni2+, Co2+ and Cu2+ are found to be 11.31, 13.88, 7.64, 4.86 and 78.67 mg/g, respectively. The adsorption and desorption cycle was studied for five cycles with minimal loss of efficiency.

Bimetallic nanoparticles, particularly those based on copper, have recently attracted a great deal of attention for the development of low cost and highly active catalysts due to the synergistic interaction between individual metal components. In this work, bimetallic Ag–Cu alloy nanoparticles were explored as a highly active and reusable catalyst for the enamination of 1,3-dicarbonyls using diverse amines. The nanocatalysts were intensively characterized by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy-energy-dispersive spectroscopy (HRTEM-EDS) and valence band and core level X-ray photoelectron spectroscopy (XPS) to study the effect of the bimetallic structure and composition. In comparison to monometallic Ag and Cu nanoparticles, the alloyed Ag–Cu nanoparticles showed a high catalytic performance and the resultant catalytic activity was dependant on the Ag to Cu ratio. This enhanced catalytic activity should be related to the electronic interaction between Ag and Cu nanoparticles formed due to the intimate contact between them. Our study may serve as a foundation for designing efficient alloyed nanocatalysts for fine chemical synthesis via enamination reactions.

Various types of water-miscible aprotic ionic liquids (ILs) with different cations (1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-octyl-3-methylimidazolium) and anions (ethylsulfate and chloride) were used as co-solvents to investigate the stability of lysozyme. Different techniques such as fluorescence, thermal absorption, and circular dichroism (CD) spectroscopy have been used for the study. Fluorescence results reveal that the addition of ILs (1-ethyl-3-methylimidazolium ethyl sulfate and 1-ethyl-3-methylimidazolium) increases the hydrophobicity around the tryptophan environment in lysozyme. CD analysis and temperature-dependent studies were done to investigate the stability of the protein. From the CD analysis, it was observed that the ILs keep the native structure of protein intact. Thermal denaturation studies depicted that the melting temperature of the protein increased in the presence of ILs (1-ethyl-3-methylimidazolium ethyl sulfate and 1-ethyl-3-methylimidazolium), which indicates the stabilization of the protein.

Semiconductor mediated photocatalysis has got enormous consideration as it has shown immense potential in addressing the overall energy and environmental issues. To overcome the earlier drawbacks concerning quick charge recombination and limited visible-light absorption of semiconductor photocatalysts, numerous methods have been produced in the past couple of decades and the most broadly utilized one is to develop the photocatalytic heterojunctions. In our work, a series of SnO2-CuO nanocomposites of different compositions were synthesized by a combustion method and have been investigated in detail by various characterization techniques, such as wide angle X-ray diffraction (XRD), UV-vis spectroscopy, transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). The results revealed that the crystal structure and optical properties of the nanocomposites were almost same for all the compositions. FE-SEM images showed that the shape of SnO2-CuO was spherical in nature and the 1: 1 Sn/Cu sample had a well-proportioned morphology. The malachite green dye was used for the photocatalytic studies in a photoreactor and monitored with a UV-visible spectrometer for different composition ratio of metal (Sn: Cu) such as 1:1, 1:2, 2:1, 1:0.5 and 0.5:1. The 1:1 ratio nanocomposite showed excellent photocatalytic degradation of 96 % compared to pure SnO2 and CuO. The mechanism of degradation and charge separation ability of the nanocomposite are also explored using photocurrent measurement study.

We report the synthesis of TiO 2-supported monometallic Ag , Sn and bimetallic AgSn nanoparticle catalysts prepared using sol–gel method via a rational nanoparticle encapsulation route. The samples were thoroughly characterized by ultraviolet-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) with image mapping and Brunauer–Emmett–Teller (BET) surface area analyzer. The supported bimetallic AgSn catalyst had the anatase structure, surface area of 50 m2/g and 2.6 ± 0.6 nm particle size. The efficiency of the catalysts was evaluated on photodegradation of methylene blue (MB) dye under visible light. The photocatalytic activity of MB was significantly enhanced in the presence of bimetallic AgSn nanoparticles (NPs) as compared to individual metal nanoparticles. Reusability study of the photocatalyst showed that the catalyst can be reused upto 5 runs with minimal loss in activity. Kinetic study revealed that the degradation reaction follows a pseudo first-order pathway.