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With the purpose of oil energy recovery as well as achieving efficiency of oil/water separation, hydrophobic mesh materials have attracted extensive attention. However, fabrication of the current methods is not environmentally friendly, has high energy consumption, and creates serious pollution. Inspired by lotus leaves and rose petals, a biomimetic superhydrophobic surface was fabricated prepared on a stainless steel mesh by an in situ chemical reduction method with simple operation and mild conditions. The results of SEM, XRD, and XPS demonstrated that the mesh shows a stable and uniform moss-like rough structured surface. The SSM/Ag/ODA mesh, which was modified by moss-like Ag nanoclusters and low surface energy agents, has excellent superhydrophobicity with an excellent oil/water separation efficiency that reached up to 99.8%. The silver mirror phenomenon formed by the Ag nanoclusters further confirmed that silver ions were reduced and attached to the surface of the mesh. Moreover, the mesh can maintain superhydrophobicity under harsh conditions, such as a high concentration of a salty solution, organic solvents, alkaline, acidic solution, and even long-time UV irradiation, etc. More importantly, the modified mesh has excellent physical stability, in which the water contact angle on the mesh can be maintained above 150° after harsh mechanical wear. The hydrophobic mesh showed great potential to be applied for highly efficient oil/water separation and oil energy recovery even under complex and harsh conditions.

The present investigation aims to remove Cr(VI) by flower like Cerium Phosphate Polypyrrole nanocomposite material (CePO4-PPY). The material was synthesized by in situ oxidative polymerization method and characterized by FTIR, Raman, XRD, XPS, Zeta potential, N2 adsorption–desorption isotherms, and TGA-DTA analysis. Field emission scanning electron microscopy and transmission electron microscopy images revealed the flower-like morphology of the synthesized nanocomposite. Meanwhile, the fabrication of polypyrrole on cerium phosphate nanoparticles provided a plentiful of active adsorption sites to interact with hexavalent chromium ions. The Cr(VI) adsorption followed the pseudo-second-order kinetic and Langmuir isotherm model showing a high adsorption capacity of 117.78 mg g−1 at room temperature at lower pH. The high tolerance capacity of CePO4-PPY in the presence of other co-anions makes it a highly efficient adsorbent. The adsorption dynamic study demonstrated that the rate-determining step was controlled by surface diffusion, pore diffusion, and film diffusion. XPS spectra confirmed the simultaneous adsorption of Cr(VI) and in situ chemical reduction to Cr(III). Regeneration studies illustrated the efficiency of more than 80%, even after five cycles. Therefore, CePO4-PPY nanocomposite could be a unique alternative to act as a promising adsorbent for the effective treatment of Cr(VI) containing wastewater.

The three-dimensional (3D) architecture of electrode materials with excellent stability and electrochemical activity is extremely desirable for high-performance supercapacitors. In this study, we develop a facile method for fabricating 3D self-supporting Ti3C2 with MoS2 and Cu2O nanocrystal composites for supercapacitor applications. MoS2 was incorporated in Ti3C2 using a hydrothermal method, and Cu2O was embedded in two-dimensional nanosheets by in situ chemical reduction. The resulting composite electrode showed a synergistic effect between the components. Ti3C2 served as a conductive additive to connect MoS2 nanosheets and facilitate charge transfer. MoS2 acted as an active spacer to increase the interlayer space of Ti3C2 and protect Ti3C2 from oxidation. Cu2O effectively prevented the collapse of the lamellar structure of Ti3C2-MoS2. Consequently, the optimized composite exhibited an excellent specific capacitance of 1459 F g-1 at a current density of 1 A g-1. Further, by assembling an all-solid-state flexible supercapacitor with activated carbon, a high energy density of 60.5 W h kg-1 was achieved at a power density of 103 W kg-1. Additionally, the supercapacitor exhibited a capacitance retention of 90% during 3000 charging-discharging cycles. Moreover, high mechanical robustness was retained after bending at different angles, thereby suggesting significant potential applications for future flexible and wearable devices.

A novel chemiresistive-type sensor for detecting sub-ppm NO2 has been fabricated using AuPt bimetal-decorated SnSe2 microflowers, which was synthesized by the hydrothermal treatment followed by in situ chemical reduction of the bimetal precursors on the surface of the petals of the microflowers. The as-prepared sensor registers a superior performance in detection of sub-ppm concentration of NO2. Functionalized by the AuPt bimetal, the SnSe2 microflower-based sensor shows a response of approximately 4.62 to 8 ppm NO2 at 130 °C. It is significantly higher than those of the sensors using the pristine SnSe2 (∼2.29) and the modified SnSe2 samples by a single metal, either Au (∼3.03) or Pt (∼3.97). The sensor demonstrates excellent long-term stability, signal repeatability, and selectivity to some typical interfering gaseous species including ammonia, acetone, formaldehyde, ethanol, methanol, benzene, CO2, SO2, and CO. The remarkable improvement of the sensitive characteristics could be induced by the electronic and chemical sensitization and the synergistic effect of the AuPt bimetal. Density functional theory (DFT) is implemented to calculate the adsorption states of NO2 on the sensing materials and thus to possibly reveal the sensing mechanism. The significantly enhanced response of the SnSe2-based sensor decorated with AuPt bimetallic nanoparticles has been found to be possibly caused by the orbital hybridization of O, Au, and Pt atoms leading to the redistribution of electrons, which is beneficial for NO2 molecules to obtain more electrons from the composite material.

Cuprous oxide (Cu2O) nanoparticles at a loading of 33.5 wt.% were impregnated in amine-functionalized mesoporous silica (NH2-SBA-15) particles, by an in situ chemical reduction method. Subsequently, Cu2O-NH2-SBA-15 hybrid was used as a modifier of glassy carbon electrode (GCE) for making a non-enzymatic glucose sensor. The optimum composition of the modifier on the GCE surface (0.47 mg Cu in Cu2O-NH2-SBA-15/cm2 surface area of GCE) resulted in a wide linearity range (0.2–15 mM glucose) and a high sensitivity of 438.3 µAcm−2 mM−1, due to the high loading of Cu2O in NH2-SBA-15 host. Furthermore, glucose was detected both in normal range (5 mM) and in hypoglycaemic range (2 mM), selectively in presence of concentrations of interfering species typically found in the normal blood, such as sodium chloride (142 mM), potassium chloride (3.7 mM), urea (4.7 mM) and ascorbic acid (0.05 mM). The response time was also less than 5 s. Therefore, it achieved the desirable sensor characteristics, like linearity, sensitivity, selectivity, and speed of response. This better performance of the sensor is mainly attributed to a high electrocatalytic activity of Cu2O nanoparticles towards glucose.

In this work, we designed the Fe3O4@mesoporous-SiO2@chitosan@polyaniline core–shell nanoparticles (Fe3O4@mSiO2@CS@PANI, hence abbr. FSCP), which can be used to capture Cr(VI) in wastewater. Rapid a...

A strategy to improve its photocatalytic performance is still a challenge for the novel Sillen–Aurivillius perovskite type Bi4NbO8Br. Herein, novel Pt modified Bi4NbO8Br composites (Pt/BNB) with sufficient oxygen vacancies were successfully fabricated via a facile in situ chemical reduction method. For one thing, the deposition of Pt nanoparticles brings about a Mott–Schottky effect at the interface to accept photo-induced electrons, leading to an efficient charge separation. For another thing, the electronic metal–support interaction of Pt and Bi4NbO8Br decreases the formation energy of oxygen defects, which could serve as active sites for O2 activation. On account of the synergetic effect of Pt and oxygen vacancies, the dominant active species-photogenerated holes are accumulated on the surface of the photocatalysts, while the additional superoxide radicals are also involved. Hence, Pt/BNB performed with excellent photocatalytic activities in the degradation of wastewater contaminants, and the kinetic rate was 4.64, 10.21, 5.53, 9.80, 1.71 and 4.05 times, respectively, those of pristine Bi4NbO8Br towards methyl orange, rhodamine B, 2,4-dichlorophenol, p-nitrophenol, ciprofloxacin and tetracycline hydrochloride.

Well-dispersed Pt quantum dots (QDs) were the first to be successfully deposited onto a PDI supramolecular nanorods surface via a simple in situ chemical reduction. Under visible light irradiation, Pt QDs/PDI composites displayed excellent photocatalytic property in the degradation of phenol. The optimum 1 wt% Pt QDs/PDI composite was found to be 6.2 times greater than pure PDI supramolecular nanorods for the degradation rate constant (k). The enhanced photocatalytic performance can be attributed to the rapid transfer and efficient separation of photogenerated carriers, originating from the effective trapping and transporting of electrons by Pt QDs. At the same time, Pt QDs were also loaded as active sites during the photocatalytic reaction. Moreover, the 1 wt% Pt QDs/PDI composite was found to have high photocatalytic stability and cycle utilization, suggesting its great potential in the area of water environmental purification.

Wound dressings composed of hydroxyethylacryl chitosan (HC) and sodium alginate (SA) were developed with antibacterial activity by loading Ag particles. The formation of Ag particle in the HC/SA films was achieved by an immersion method through in situ chemical reduction of AgNO3 solution and confirmed by FTIR, SEM-EDS, XRD and XRF techniques. The effect of Ag loading in the Ca-crosslinked HC/SA films with different crosslinking density was studied on swelling behavior, mechanical properties, cytotoxicity, antibacterial activity and drug release behavior. The results showed that Ag loading increased swelling degree in phosphate buffer and enhanced mechanical properties. The HC/SA films with Ag loading exhibited antibacterial activity against E. coli and S. aureus as well as no toxicity on Vero cell. In vitro drug release profiles of the films were examined using para-acetylaminophenol, as a soluble model drug. The increase in crosslinking density and Ag loading prolonged drug releasing rate and almost the films showed linearity profiles. It can be concluded that the HC/SA films with Ag loading have a promising potential in modern wound dressings with antibacterial property and controlled drug release.

Ferrous iron-bearing minerals are important reductants in the contaminated subsurface, but their availability for the reduction of anthropogenic pollutants is often limited by competition with other electron acceptors including microorganisms and poor accessibility to Fe(II) in complex hydrogeologic settings. The supply of external electron donors through in situ chemical reduction (ISCR) has been proposed as one remediation approach, but the quantification of pollutant transformation is complicated by the perturbations introduced to the subsurface by ISCR. Here, we evaluate the application of compound specific isotope analysis (CSIA) for monitoring the reduction of 2,4-dinitroanisole (DNAN), a component of insensitive munitions formulations, by mineral-bound Fe(II) generated through ISCR of subsurface material from two field sites. Electron balances from laboratory experiments in batch and column reactors showed that 3.6% to 11% of the total Fe in the sediments was available for the reduction of DNAN and its partially reduced intermediates after dithionite treatment. The extent of DNAN reduction was successfully quantified from its N isotope fractionation measured in the column effluent based on the derivation of a N isotope enrichment factor, eN, derived from a comprehensive series of isotope fractionation experiments with numerous Fe(II)-bearing minerals as well as dithionite-reduced subsurface materials. Our observations illustrate the utility of CSIA as a robust approach to evaluate the success of in situ remediation through abiotic contaminant reduction.

Chromium contamination is a serious environmental issue in areas affected by leather tanning and metal plating, and green rust sulfate has been tested extensively as a potential material for in situ chemical reduction of hexavalent chromium in groundwater. Reported products and mechanisms for the reaction have varied, most likely because of green rust’s layered structure, as reduction at outer and interlayer surfaces might produce different reaction products with variable stabilities. Based on studies of Cr(III) oxidation by biogenic Mn (IV) oxides, Cr mobility in oxic soils is controlled by the solubility of the Cr(III)-bearing phase. Therefore, careful engineering of green rust properties, i.e., crystal/particle size, morphology, structure, and electron availability, is essential for its optimization as a remediation reagent. In the present study, pure green rust sulfate and green rust sulfate with Al, Mg and Zn substitutions were synthesized and reacted with identical chromate (CrO42−) solutions. The reaction products were characterized by X-ray diffraction, pair distribution function analysis, X-ray absorption spectroscopy and transmission electron microscopy and treated with synthetic δ-MnO2 to assess how easily Cr(III) in the products could be oxidized. It was found that Mg substitution had the most beneficial effect on Cr lability in the product. Less than 2.5% of the Cr(III) present in the reacted Mg-GR was reoxidized by δ-MnO2 within 14 days, and the particle structure and Cr speciation observed during X-ray scattering and absorption analyses of this product suggested that Cr(VI) was reduced in its interlayer. Reduction in the interlayer lead to the linkage of newly-formed Cr(III) to hydroxyl groups in the adjacent octahedral layers, which resulted in increased structural coherency between these layers, distinctive rim domains, sequestration of Cr(III) in insoluble Fe oxide bonding environments resistant to reoxidation and partial transformation to Cr(III)-substituted feroxyhyte. Based on the results of this study of hexavalent chromium reduction by green rust sulfate and other studies, further improvements can also be made to this remediation technique by reacting chromate with a large excess of green rust sulfate, which provides excess Fe(II) that can catalyze transformation to more crystalline iron oxides, and synthesis of the reactant under alkaline conditions, which has been shown to favor chromium reduction in the interlayer of Fe(II)-bearing phyllosilicates.

Groundwater at an abandoned industrial area near Bergamo, Italy, was historically contaminated by tetrachloroethylene (PCE) (>100 g/L) and, to a lesser extent, by trichlorethylene (TCE), dichloropropane (DP) and 1,1,2,2-tetrachloroethane (R-130). A liquid reagent (EHC Liquid) was selected for remediation of groundwater at the site. The reagent is provided in two parts: EHC Liquid Mix (a soluble organo-iron salt), and ELS Microemulsion (a lecithin-based carbon substrate), and is designed to promote both in situ chemical reduction (ISCR) and enhanced reductive dechlorination (ERD) to destroy chlorinated organic compounds. The two components are mixed with water and injected into the subsurface. Once in groundwater, EHC Liquid rapidly generates highly reduced conditions, favouring both biotic and abiotic dechlorination reactions. Less than 6 months after the injection of EHC Liquid in the main source area, concentrations of the target contaminants had reached the site-specific remediation target values (CSC Legislative Decree 152/06) in the main monitoring piezometers present in the area, thus demonstrating the effective establishment of enhanced biotic and abiotic reducing conditions and degradation of the target compounds.

In this study, composites composed of all-inorganic perovskite quantum dots (QDs) of CsPbBr3 encapsulated in a metal–organic framework of ZIF-8 (CsPbBr3@ZIF-8) were prepared using an in situ chemical reduction method. For the first time, the CsPbBr3@ZIF-8 composites were used for surface-enhanced Raman scattering (SERS). The CsPbBr3@ZIF-8 composites remained effective and emitted normal luminescence under UV illumination after 200 days of storage at room temperature, indicating that they were able to overcome the instability of perovskite QDs at room temperature and that they can be stored for long-term use. The enhancement factor value is 1.17 × 105. The adsorption behavior of 4-mercaptopyridine (4-MPY) on the CsPbBr3@ZIF-8 composites was studied using typical SERS spectral bands, and these were contrasted with the SERS spectra on silver films. The enhancement mechanism is attributed to a charge transfer contribution. The results indicate that CsPbBr3@ZIF-8 composites have potential application in SERS detection.

A simple and controllable route is presented for the construction of two-dimensional (2D) flower-shaped Au@Ag nanoparticle (NP) arrays through in situ chemical reduction growth of Ag nanosheets on Au NP arrays. Such micro-/nanostructured arrays composed of interlaced Ag nanosheets can act as good candidates for SERS substrates due to numerous “hot spots” generated by the rough surface of the nanosheets and small nanogaps less than 10 nm between the Au@Ag NPs. After optimizing the experimental parameters (an array periodicity of 500 nm and a growth time of 20 min), the flower-shaped Au@Ag NP array as a SERS substrate has a low detection limit (10−11 M) for thiram, which is a commonly used pesticide molecule and causes environmental pollution due to excessive use. The array also exhibits very good SERS signal uniformity and repeatability (RSD ≈ 7.4%) because of the abundance of “hot spots” and highly ordered structures on a large scale. Such 2D flower-shaped Au@Ag NP arrays with economical preparation and excellent SERS properties are meaningful for the practical applications of organic molecular Raman detection.

In this work, a novel nanocomposite containing silver nanoparticles (AgNPs) embedded poly(1-naphthylamine) nanospheres (Ag/PNA) was prepared by in situ chemical reduction of silver nitrate. The structure, composition, and morphology of the prepared Ag/PNA nanocomposites were established by Fourier transform infrared spectrometry, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The electrochemical properties of the PNA and Ag/PNA-modified carbon paste electrodes were analyzed using cyclic voltammetry (cyclic voltammogram) and electrochemical impedance spectroscopy. It is observed that the electrochemical and charge transfer characteristics of PNA have significantly enhanced upon the incorporation of AgNPs. The prepared Ag/PNA nanocomposite has shown impressive electrocatalytic and electrochemical sensing performance toward H2O2. Remarkably, the present Ag/PNA-based enzymeless voltammetric H2O2 sensor showed a wide detection range in the concentration range of 1–3000 μM with a lower detection limit of 0.972 μM. The study revealed that Ag/PNA-modified carbon paste electrodes are an ideal platform for the fabrication of low-cost non-enzymatic H2O2 sensor with high sensitivity, good reproducibility, better selectivity, and stability.

In this work, a series of flower-like Bi/BiOClxBr(1−x) heterojunction photocatalysts have been developed. Bi nanoparticles were grown on the BiOClxBr(1−x) nanosheets via an in situ chemical reduction with the assistance of cetyltrimethylammonium chloride and cetyltrimethylammonium bromide aqueous solution. The in situ growth of Bi nanoparticles on the BiOClxBr(1−x) nanosheets could not only give rise to the optical absorption in the visible region, but also promote the photocatalytic performance of BiOClxBr(1−x). Bi/BiOCl0.8Br0.2 exhibited the highest photocatalytic performance, which could completely degrade RhB in 12 min under the UV light irradiation and 6 min under visible light irradiation, respectively. Moreover, holes and superoxide radicals were verified to be the primarily active species in the photocatalytic process.

Novel PdAg bimetallic alloy nanoparticle modified graphitic carbon nitride (g-C3N4) nanosheet was designed and prepared by an in situ chemical reduction procedure. By optimizing the loading content of the PdAg alloy NPs, the PdAg/g-C3N4 composite photocatalyst showed a champion photocatalytic hydrogen generation rate of 3.43 mmol h−1 g−1, and the apparent quantum yield (AQY) was determined to be 8.43% at 420 nm. Moreover, the photoluminescence and photoelectrochemical experimental results suggest that a higher separation efficiency of photo-induced charge carriers (e- and h+) was obtained after loading PdAg alloy NPs on g-C3N4. The experimental outcomes indicate that there is a synergistic effect formed between PdAg and g-C3N4, which could significantly promote the charge transfer photo-induced charge carriers in the hybrid sample. A reasonable catalytic mechanism for the enhanced photocatalytic performance of the composite photocatalyst was proposed and verified by TRPL measurement, which could be taken as a guidance for the development of novel high performance catalytic system.

Here, by a simple one-step in situ chemical reduction method, the AgxCuy alloy was tailored on the surface of mesoporous TiO2 (M-TiO2), therefore, a series of bi-functional mesoporous TiO2 nanohybrids (M-TiO2/AgxCuy) for both surface enhanced Raman scattering (SERS) detection and photocatalytic degradation of ampicillin (AMP) were achieved. The composition and structure of the nanohybrids were well characterized using XRD, TEM, XPS and HRTEM-EDS measurements. Results indicated that AgxCuy alloy was mainly attached around the pores of M-TiO2 which may generate more active sites than nonporous P25−Ag−Cu. Thus, the M-TiO2/AgxCuy nanohybrids could be used as efficient SERS substrates to sensitively monitor the AMP in water with lower detection limit (˜ 1 ppt) than P25−Ag−Cu. Besides, the M-TiO2/Ag3Cu1 nanohybrid also showed higher photocatalytic activities for the degradation of AMP under UV irradiation over the M-TiO2/Ag, the M-TiO2/Cu and the P25−Ag−Cu. This work provided a simple and effective approach to synthesize bi-functional nanohybrids for detection and degradation of organic contaminants in wastewater.

International audience; The efficiency of zero-valent iron (Fe-0)for the degradation of contaminants in water or soil can be highly reduced by side reactions with oxygen or water. This work was conducted to test whether this drawback can be effectively suppressed by the carbonation of Fe-0 with pyrolyzed biomass, which forms a Fe3C composite. The composite Fe3C was characterized and its reactivity and stability were assessed in batch tests with methyl orange (MO) as a model pollutant. The results indicated that the removal rate of MO on Fe3C composite was higher than that of Fe-0 (7.587 mg/(g.min) vs. 4.306 mg/(g.min)) at pH 4, where the degradation mechanism was confirmed by high-performance liquid chromatography-mass spectrometry. More importantly, the produced iron oxide in the Fe3C composite was highly suppressed. Regeneration studies showed that after three times of cycling, the removal efficiency of MO on Fe3C composite was kept to 99.42%, but Fe-0 almost lost its reactivity. In situ chemical reduction of a colorimetric redox probe (indigo-5, 5'-disulfonate, I2S) quantitatively demonstrated that Fe3C composite has the reduction kinetics of I2S obviously slower than Fe-0, indicating that Fe3C composite improved the stability of incorporated Fe-0 to resist the side oxidation.

A new hybrid material consisting of β-chitin and dicalcium phosphate anhydrous (DCPA) with interesting functional properties was successfully prepared at moderate temperature via mechanochemical route and served as a support for copper nanocatalyst (Cu(NPs)) in the degradation of methylene blue (MB). Cu(NPs) were obtained from the in situ chemical reduction of copper ions using an aqueous solution of NaBH4. The resulting Cu(NPs)/β-chitin/DCPA was characterized by several analytical techniques, and the obtained results were compared to those of Cu(NPs) supported on pure DCPA(Cu(NPs)/DCPA). The physicochemical analysis showed that the incorporation of β-chitin enhances the chemical stability and physical properties of the DCPA structure as well as the retention capacity of copper ions at the surface of β-chitin/DCPA. Catalytic performances obtained on Cu(NPs)/β-chitin/DCPA show a first-order kinetic and exhibited excellent reductive activity of MB with rate constant of 57.8 × 10−2 min−1, higher than that of Cu(NPs)/DCPA (9.5 × 10−2 min−1). By comparison with other reported Cu catalysts, Cu(NPs)/β-chitin/DCPA presents better catalytic efficiency due to the anchoring effect of β-chitin which maintains good dispersion and prevents Cu(NPs) against agglomeration without the addition of capping agents or surfactants templates. The high catalytic efficiency of Cu(NPs)/β-chitin/DCPA material was confirmed by the recyclability test, in which after four cycles, the MB is entirely degraded without any delay of the process.

Application of in situ chemical oxidation or reduction (ISCO/ISCR) technologies for contaminated soil remediation and its subsequent impact on soil is gaining increased attention. Reductive reactivity, generated from green tea (GT) extract mixed with ferrous (Fe2+) ions under alkaline conditions (the alkaline GT/Fe2+ system), has been considered as a promising ISCR process; however, its impact on soil has never been studied. In this study, the impact of applying the alkaline GT/Fe2+ system on soil was evaluated by analyzing the variations of the soil microbial community, diversity, and richness using next-generation 16S rRNA amplicon sequencing while mimicking the lindane-contaminated soil remediation procedure. Lindane was reductively degraded by the alkaline GT/Fe2+ system with reaction rate constants of 0.014 to 0.057 μM/h depending on the lindane dosage. Environmental change to the alkaline condition significantly decreased the microbial diversity and richness, but the recovery of the influence was observed subsequently. Bacteria that mainly belong within the phylum Firmicutes, including Salipaludibacillus, Anaerobacillus, Bacillaceae, and Paenibacillaceae, were greatly enhanced due to the alkaline condition. Besides, the dominance of heterotrophic, iron-metabolic, lindane-catabolic, and facultative bacteria was observed in the other corresponding conditions. From the results of principal component analysis (PCA), although dominant microbes all shifted significantly at every lindane-existing condition, the set of optimal lindane treatment with the alkaline GT/Fe2+ system had a minimized effect on the plant growth-promoting bacteria (PGPB). Nitrogen-cycling-related PGPB is sensitive to all factors of the alkaline GT/Fe2+ system. However, the other types, including plant-growth-inducer producing, phosphate solubilizing, and siderophore producing PGPB, has less impact under the optimal treatment. Our results demonstrate that the alkaline GT/Fe2+ system is an effective and soil-ecosystem-friendly ISCR remediation technology for lindane contamination.

A glassy carbon electrode (GCE) coated with delafossite CuCrO2 loading on the nitrogen-doped reduced graphene oxide (N-rGO) and multiwalled carbon nanotubes (MWCNT) composite (N-rGO-MWCNT/CuCrO2) was applied to the hydrogen evolution reaction and Bisphenol-A (BPA) detection. First, the N-rGO-MWCNT composite was prepared by in situ chemical reduction with caffeic acid as a reducing agent. Then, CuCrO2 was accumulated on the N-rGO-MWCNT surface to form N-rGO-MWCNT/CuCrO2 composite. The morphology structure of the N-rGO-MWCNT/ CuCrO2 composite was analyzed by different characterization techniques. Besides, the GCE/N-rGO-MWCNT/CuCrO2 composite electrode was investigated for hydrogen evolution reaction (HER), which shows an excellent electrocatalytic activity with a low over-potential, increasing reduction current, and a small Tafel slope of 62 mV·dec−1 at 10 mA·cm−2 with long-term stability. Moreover, the electrochemical determination of BPA was in the range of 0.1-110 µM, and low detection limit of 0.033 µM (S/N = 3) with a higher sensitivity of 1.3726 µA µM−1 cm−2. Furthermore, the prepared GCE/N-rGO-MWCNT/CuCrO2 electrode shows effective detection of BPA in food samples with acceptable recoveries. Hence, the finding of GCE/N-rGO-MWCNT/CuCrO2 can be observed as an impressive catalyst to the electrocatalytic activity of HER and BPA oxidation.

A novel Lanthanum phosphate polyaniline (LaPO4-PANI) nanocomposite was synthesized by the simple sol-gel technique. The nanocomposite prepared at 1:1 ratio provided the highest ion exchange capacity and selective adsorption of Cr(VI). The phase composition and particle morphology of the as-prepared material was evaluated by XRD, FESEM and TEM analyses. The FTIR, Raman, and TGA data inferred the definite chemical interaction between the organic and inorganic counterparts in the formation of LaPO4-PANI. The selective adsorption of Cr(VI) was estimated by evaluating the distribution coefficient, electrical double layer theory as well as valency and Pauling’s ionic radii of interfering ions (phosphate, iodide, sulfate, chloride, sulfide). The high tolerance capability of LaPO4-PANI against the interfering ions made it appropriate for selective and efficient removal of Cr(VI) ions from solutions. The nanocomposite showed the highest removal percentage of 98.6% towards Cr(VI) in a wide pH range of 2–6 at room temperature, as compared to sole lanthanum phosphate (56%) and polyaniline (75%). The XPS analysis revealed the adsorption mechanism due to the combined effect of both adsorption and reduction. Cr(VI) is adsorbed through electrostatic interactions while the = N−/−NH- group facilitated the in situ chemical reduction. The procured results make the LaPO4-PANI nanocomposite a promising adsorbent for the removal of Cr(VI).

A three-dimensional porous SERS powder material, Ag nanoparticles-engineered-silica aerogel, was developed. Utilizing an in situ chemical reduction strategy, Ag nanoparticles were densely assembled on porous aerogel structures, thus forming three-dimensional “hot spots” distribution with intrinsic large specific surface area and high porosity. These features can effectively enrich the analytes on the metal surface and provide huge near field enhancement. Highly sensitive and homogeneous SERS detections were achieved not only on the conventional liquid analytes but also on gas with the enhancement factor up to ∼108 and relative standard deviation as small as ∼13%. Robust calibration curves were obtained from the SERS data, which demonstrates the potential for the quantification analysis. Moreover, the powder shows extraordinary SERS stability than the conventional Ag nanostructures, which makes long term storage and convenient usage feasible. With all of these advantages, the porous SERS powder material can be extended to on-site SERS “nose” applications such as liquid and gas detections for chemical analysis, environmental monitoring, and anti-terrorism.

In this study, the liquid phase and vapor phase procedures for silylating cellulose microfibers by hexamethyldisilazane (HMDS) were compared in terms of efficiency. The influence of functionalization degree on the morphology of microfibers and their interaction with polydimethylsiloxane (PDMS) matrix has been investigated. The antibacterial properties of silylated cellulose microfibers hybridized with Ag nanoparticles, obtained by in situ chemical reduction, were also studied. Sample morphology investigations were carried out using spectroscopy and microscopy techniques (FTIR, XPS, TEM, SEM, EDS, XPS). Trimethylsilyl moieties appear on the surface of the cellulose microfibers after modification and improve the dispersibility of the microfibers, allowing strong interaction with the PDMS matrix and favoring its crosslinking density. Microfibers functionalized by the vapor phase of HMDS show smoother surfaces with higher concentrations of Si-containing groups, resulting in a more hydrophobic wetting behavior and a greater influence on the mechanical properties of the polymer. The silylated cellulose microfiber&ndash, Ag nanohybrid shows stronger antimicrobial activity towards Gram-positive and Gram-negative bacteria strains compared to that of the untreated hybrid. A PDMS composite loaded with this hybrid exhibits the ability to inhibit bacterial growth.

International audience; Chlorinated organic compounds (COCs) are common anthropogenic contaminants of soil and groundwater. COCs were industrially produced for different applications, such as dry cleaning, degreasing, or as pesticides. The presence of COCs in the environment is a major concern because of their toxicity and persistence. The most widely used method for their remediation is the conventional pump-and-treat system. However, this technology can hardly achieve a complete remediation because of geological characteristics and the presence of pore space pollution/adsorbed pollution, leading to a residual saturation. Hence, in addition to the improvement of pump-and-treat systems, in situ chemical processes have been largely developed. These chemical processes involve the injection of chemical reagents for the removal of residual source pollution and/or the treatment of plume contamination. Chemical degradation of COCs can be achieved by oxidative or reductive processes. If chemical oxidation has been first developed for in situ application, chemical reduction is one of the most important emerging remediation techniques for COCs treatment. Due to the electronegative character of chlorine substituents, COCs can effectively be transformed via reductive pathways. Moreover, reductive dechlorination has shown higher efficiency on highly chlorinated compounds. This chapter focuses on the presentation of the chemical reduction of the most common COCs pollutants, followed by kinetic and mechanistic approaches related to the use of iron-based particles. Developments on in situ chemical reduction technologies in order to enhance remediation rates are also exposed. Influence of environmental conditions for in situ applications is then developed. Finally, a case study is presented.

A series of Palladium (Pd) supported multi-walled carbon nanotubes (Pd/MWCNTs) were synthesized via modified impregnation of Pd2+ followed by in situ chemical reduction with ethanol, NaBH4, and H2 as the reducing agent (referred as Pd/MWCNTs-E, Pd/MWCNTs-B, and Pd/MWCNTs-H, respectively). The electrocatalytic hydrodechlorination of 4-chlorophenol (4-CP), a highly toxic, cancerigenic, and bio-refractory contaminant, was investigated in a three-dimensional electrochemical reactor with Pd/MWCNTs as the particle electrodes. Nearly 100% of 4-CP could be efficiently dechlorinated and completely converted into phenol within 30 min under optimized conditions. Transmission electron microscope (TEM) and X-ray diffraction (XRD) results indicated that the small Pd nano-particles (6.4–13.1 nm) were uniformly supported on the surface of MWCNTs and formed face centered cubic (fcc) structure in all as-prepared catalysts. The removal efficiency of 4-CP was significantly affected by the size of loaded Pd nano-particles, where Pd/MWCNTs-B (100%, 6.4 nm) > Pd/MWCNTs-E (60%, 9.5 nm) > Pd/MWCNTs-H (29%, 13.1 nm). Effects of current density, initial pH, and initial dissolution oxygen (DO) on the 4-CP removal were also investigated. Scavenger experiments confirmed that indirect reduction by atomic H∗ was responsible for the reductive dechlorination of 4-CP. The stability of Pd/MWCNTs-B for the 4-CP dechlorination was also exhibited in repetitive experimental cycles.

Pools of chloroethenes are more recalcitrant in the transition zone between aquifers and basal aquitards than those elsewhere in the aquifer. Although biodegradation of chloroethenes occur in this zone, it is a slow process and a remediation strategy is needed. The aim of this study was to demonstrate that combined strategy of biostimulation and in situ chemical reduction (ISCR) is more efficient than the two separated strategies. Four different microcosm experiments with sediment and groundwater of a selected field site where an aged perchloroethene (PCE)-pool exists at the bottom of a transition zone, were designed under i) natural conditions, ii) biostimulation with lactic acid, iii) in situ chemical reduction (ISCR) with zero valent iron (ZVI) and under iv) a combined strategy with lactic acid and ZVI. Biotic and abiotic dehalogenation, terminal electron acceptor processes and evolution of microbial communities were investigated for each experiment. The main results where: i) limited reductive dehalogenation of PCE occurs under sulfate-reducing conditions; ii) biostimulation with lactic acid promotes a more pronounced reductive dehalogenation of PCE in comparison under natural conditions, but resulted in an accumulation of cis-dichloroethene (cDCE); iii) ISCR with zero-valent iron (ZVI) facilitates a sustained dehalogenation of PCE and its metabolites to non-halogenated products, however, the iv) combined strategy results in the fastest and sustained dehalogenation of PCE to non-halogenated products in comparison of all four set-ups. These findings suggest that biostimulation and ISCR with ZVI are the most suitable strategy for a complete reductive dehalogenation of PCE-pools in the transition zone.

Mesoporous gold (mesoAu) nanospheres support enhanced (electro)catalytic performance owing to their three-dimensional (3D) interior mesochannels that expose abundant active sites and facilitate electron/mass transfers. Although various porous Nanostructured Au has been fabricated by electrochemical reduction, alloying–dealloying and hard/soft templating methods, successful synthesis of mesoAu nanospheres with tailorable sizes and porosities remains a big challenge. Here we describe a novel surfactant-directed synthetic route to fabricate mesoAu nanospheres with 3D interconnected mesochannels by using the amphiphilic surfactant of C22H45N+(CH3)2–C3H6–SH (Cl−) (C22N–SH) as the mesopore directing agent. C22N–SH can not only self-reduce trivalent Au(III)Cl4− to monovalent Au(I), but also form polymeric C22N–S–Au(I) intermediates via covalent bonds. These C22N–S–Au(I) intermediates facilitate the self-assembly into spherical micelles and inhibit the mobility of Au precursors, enabling the crystallization nucleation and growth of the mesoAu nanospheres via in situ chemical reduction. The synthetic strategy can be further extended to tailor the sizes/porosities and surface optical properties of the mesoAu nanospheres. The mesoAu nanospheres exhibit remarkably enhanced mass/specific activity and improved stability in methanol electrooxidation, demonstrating far better performance than non-porous Au nanoparticles and previously reported Au nanocatalysts. The synthetic route differs markedly from other long-established soft-templating approaches, providing a new avenue to grow metal nanocrystals with desirable nanostructures and functions.

In situ chemical reduction using commercial zero valent iron microparticles (ZVIm) resulted to be an efficient technique for the removal of recalcitrant and toxic chlorinated organic compounds (COCs) dissolved in groundwater. Groundwater was obtained from Bailin’s landfill (Sabinanigo, Spain), where liquid and solid wastes of an old lindane factory were uncontrollably dumped during decades. 28 COCs were identified and quantified by gas chromatographic analysis: five isomers of hexachlorocyclohexane (α, β, e, γ, δ-HCH), benzene, 10 chlorobenzenes and 12 cyclic non-aromatic organochlorine compounds (ΣCOCs = 93 mg L−1). Batch-wise and column experiments were carried out using soil and groundwater from the polluted landfill. It was found that the dechlorination rate increases with the chlorine content of the organic molecule. Non-aromatic COCs with high chlorine content (from 5 to 7 atoms), as well as HCHs, were very rapidly eliminated in the presence of ZVIm via dechloroelimination, while conversions from 60% to 80% were obtained for chlorobenzenes at the end of the treatment, the last ones, dechlorinated via hydrogenolysis. It has been proved that ZVIm appears as an efficient, stable and cost-effective treatment for COCs reduction and the results obtained in the laboratory can be used at full scale. Therefore it was concluded that ZVIm can be used for the on site treatment of the pumped groundwater and also, for the in situ treatment (as permeable reactive barriers (PRBs)) of the groundwater, leading to the complete degradation of the most toxic COCs, those with higher chlorine content, less aromaticity and lower vapor pressure.

Uniform dispersion of ultrafine spherical silver nanoparticles (NPs) was obtained over the surface of Fe3O4@SiO2@KIT-6 core–shell support via functionalization of the mesoporous KIT-6 shell by aminopropyltriethoxysilane, followed by coordination of Ag+ ions and in situ chemical reduction with sodium borohydride. The obtained hybrid material, Fe3O4@SiO2@KIT-6-Ag nanocomposite, was fully characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, and used as an efficient catalyst for selective reduction of nitroaromatic compounds in aqueous solution at ambient temperature and neutral pH [nine examples, apparent rate constants at 25 °C, k (min−1), 0.112–0.628]. As a non-aromatic example, nitrofurazone which is a cytotoxic antibiotic was also reduced selectively at nitro group without reduction of other functionalities. Fe3O4@SiO2@KIT-6-Ag NPs also showed potential ability to act as catalyst for reduction of nitromethane in aqueous solution which can provide a colorimetric method for detection of nitromethane in solution down to 0.9 × 10−4 mol L−1. Fe3O4@SiO2@KIT-6-Ag nanocomposite was also screened for its antibacterial activity, and satisfactory results were obtained in comparison with drug references including Tetracycline, Chloramphenicol and Cefotaxime as positive controls, on gram negative Escherichia coli and Pseudomonas aeroginosa. Ease of recycling of the Fe3O4@SiO2@KIT-6-Ag is another benefit of this nanocatalyst. Under the optimized conditions, the recycled catalyst showed 15% loss of efficiency after five successive runs.

Non-noble metal Cd nanoparticles, as an efficient cocatalyst, are successfully constructed onto the surface of hexagonal CdS nanorods (CdS NRs) for the photocatalytic hydrogen evolution reaction by a facile in situ chemical reduction approach based on a thermal treatment process. The in situ introduction of Cd can significantly improve the photocatalytic H2 production performance of CdS NRs in sodium sulfide and sodium sulfite aqueous solutions under visible light irradiation. The superior electrical conductivity of metallic Cd and the intimate interfacial contact between Cd and CdS NRs are suggested to account for the enhanced light absorption intensity, more efficient charge separation, and faster interfacial charge migration, resulting in the dramatically promoted photocatalytic H2 production activity. This work provides a new route for the in situ deposition of Cd nanoparticles onto CdS and other Cd-containing semiconductor photocatalysts with desired morphologies.

In the present work, a newly synthesized hybrid β-chitin/dicalcium phosphate anhydrous (DCPA) loaded with copper nanoparticles Cu(NPs) was investigated as an antibacterial agent using various strains. The hybrid β-chitin/DCPA was obtained via a mechano-chemical route and the Cu(NPs) supported over β-chitin/DCPA matrix was successfully synthesized from Cu(II) ions using the ultrasound-assisted method followed by in situ chemical reduction with sodium borohydride. All the prepared materials were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–vis diffuse reflectance spectroscopy (DRS), simultaneous thermogravimetry/differential thermal analysis (TG/DTA), and scanning electron microscopy (SEM-EDS). The localized surface plasmon resonance (LSPR) of Cu(NPs) after the reduction process was identified by the optical absorption spectroscopy, in the visible light region around 600 nm. The antibacterial activity of Cu-based materials was investigated against series of Gram-positive bacteria (S. aureus, L. monocytogenes) and Gram-negative (E. coli, P. aeruginosa) strains, using the microtitration assay by determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). Among the materials tested, Cu(NPs)/β-chitin/DCPA exhibited a high antibacterial effect exceeding CuII-β-chitin/DCPA and many others reported antibacterial agents, with a MIC value of 125 μg.mL−1 (6 μg.mL−1 of copper). The excellent antibacterial result was related to high dispersion properties of the hybrid support (β-chitin/DCPA) which avoid the aggregation of Cu(NPs) via various surface bonds with β-chitin biopolymer. Copper-based materials synthesized here exhibit promising antibacterial activities which can be explored in more details in others bacterial strains.

Amorphous semiconductors usually suffer from low photocatalysis efficiency due to the fast charge recombination rate. In this work, to activate the amorphous Bi2WO6, Bi2O3 and Bi particles were in sequence deposited over its surface via a facile in situ chemical reduction of amorphous Bi2WO6 by NaBH4 at room temperature. In the resultant ternary Bi/Bi2O3/Bi2WO6, the well-formed heterojunctions (i.e. Bi-Bi2O3 and Bi2O3-Bi2WO6) and the surface plasmon resonance effect of Bi both contribute to an increase in charge carrier concentration, an efficient e−/h+ separation and then an enhanced visible light photocatalytic performance. The molar ratio of Bi, Bi2O3 and Bi2WO6 in composite can be modulated by the dosage of NaBH4, and consequently the amount of each heterojunction (i.e. Bi/Bi2O3 or Bi2O3/Bi2WO6) as well as the intensity of SPR effect could be tuned. The photocatalytic NO removal test under visible light irradiation shows that BWO-0.8 (0.8 denotes the molar ratio of NaBH4 to Bi2WO6) presents a maximum NO removal efficiency of 55.4%, much higher than that of the pristine amorphous Bi2WO6 (10%). The enhanced activity can be attributed to the balanced SPR effect of Bi metal and the heterojunction effect, making their overall contribution maximized. The pathway study of photocatalytic NO oxidation by in situ FT-IR suggests that NO is converted to nitrates adsorbed over the catalyst surface. The present work could provide a new approach to activate the amorphous semiconductors for efficient visible light photocatalysis.

In this work, ultrasound assisted catalytic removal of Rhodamine B (RhB) dye has been carried out in the presence of reduced Graphene Oxide enveloped Copper Phthalocyanine nanotube (RGO-CuPc) for the first time. This RGO-CuPc nanocomposite has been synthesized by in situ chemical reduction of Graphene Oxide (GO) with CuPc tube. Then our as prepared composite and pristine CuPc tubes are well characterized by various spectroscopic techniques such as X-Ray Diffraction, UV–vis and microscopic techniques like FESEM, HRTEM etc. Electrochemical EIS measurement has also been carried out to investigate charge transfer mechanism. These results confirm the purity of the as prepared samples. Efficient sonocatalytic RhB dye removal upto ∼92.22% is achieved by RGO-CuPc composite within 100 min as compared to pristine CuPc tube (∼70%). A plausible reaction pathway towards dye removal is discussed in detail. Also degradation performance in the presence of enhancer and scavenger has been investigated.

In this work, graphene supported Pt (Pt/G) and NiPt nanoparticles (NiPt/G) were synthesized by in situ chemical reduction of graphene oxide, Ni+2 and Pt+4 ions. The structural investigation was performed by Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS), Brunauer, Emmett, and Teller (BET) analysis, Field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The electrocatalytic activity of the Pt/G and PtNi/G catalysts toward BH4− oxidation in alkaline media was investigated by means of cyclic voltammetry (CV) and chronoamperometry (CA). The results showed that the catalytic activity of the PtNi/G catalyst toward NaBH4 electrooxidation was higher than that of Pt/G because of the synergistic effect between Pt and Ni. A direct borohydride-hydrogen peroxide fuel cell (DBHPFC) was fabricated using Pt/G (0.5 mg cm−2) as cathode catalyst and NiPt/G as anode catalyst. The maximum power density was 64.9 mW cm−2 at 60 °C, 1 M NaBH4 and 2 M H2O2 for anodic loading of 2 mg cm−2 and 60.4 mW cm−2 at 60 °C, 1 M NaBH4 and 2 M H2O2 for anodic loading of 1mg cm−2.

Cellulose/graphene nanocomposite films are prepared by dispersing graphene oxide (GO) and dissolving cellulose homogeneously in alkaline–urea aqueous solution followed by in situ chemical reduction of GO to rGO. The efficient and eco-friendly reduction process renders these novel composites high electrical conductivity as well as good mechanical properties. As demonstrated on composites with 5 wt% rGO, the rGO/cellulose composite films can be applied as multifunctional sensor materials responding to different external stimuli, such as temperature, humidity, stress/strain, and liquids by electrical resistance changes.

A flexible polyamide@Ag hybrid nanoarray film was fabricated as a highly sensitive and disposable SERS substrate for sensing label-free adenosine. Through the combination of silver nanoparticle (AgNP) self-assembly onto polyamide and in situ chemical reduction for further AgNP growth under specific conditions, a SERS-active metal “hat” with a large number of nanogaps was formed on the surface of the nanoarrays. This in situ chemical reduction step can overcome the size limitation of direct self-assembly of AgNPs onto the array. The resultant hybrid substrate possesses both a high degree of structural stability and an orderly spatial arrangement, which are beneficial for the uniform distribution of hotspots on the substrate. Additionally, its SERS performance was improved by more than an order of magnitude relative to that of the directly self-assembled PA@Ag substrate, and the detection limit for rhodamine 6G (R6G) could reach 10−14 M. Adenosine, a possible lung cancer biomarker, was detected with this substrate, and the limit of detection could reach 10−8 M. To further increase the detection limit, 4-mercaptophenylboronic acid-modified AgNPs were introduced to form Ag-adenosine-Ag molecular bridges via the boronate affinity technique. This strategy can ensure that adenosine is located in hotspots as a connecting medium. Subsequently, additional Raman hotspots were generated on the active Ag “hat” surface, thereby achieving a secondary enhancement of the adenosine signal with a detection limit as low as 9.83 × 10−10 M.

Porous polymer microspheres with interconnective open pores have attracted significant interest, owing to their unique properties as compared to those of traditional microspheres. However, developing a facile synthetic method to produce these unique particles remains a challenge. Herein, a method is proposed to produce highly porous polystyrene (PS) microspheres with interconnective open pores and a uniform size distribution, which were prepared by simply dispersing PS seed particles in an oil-in-water emulsion system. The morphological evolutions of the PS microspheres exposed to different types of oil-in-water emulsions were systematically investigated, and the relationship between the colloidal stability of the emulsions and the final structure of the PS microspheres was studied. Based on these results, the best oil-in-water system for synthesizing highly porous PS microspheres with interconnected open pores was found. The proposed synthetic method was demonstrated to offer significant advantages over previously developed techniques; it was simple, fast, and easy to process, and did not require special additives such as surfactants, complex techniques, etching processes to generate pores, and sophisticated equipment. Catalytic microreactors were fabricated by synthesizing mono- and bimetallic nanocrystals on the surface of the porous microspheres via in situ chemical reduction. When the microreactors were used as a heterogenous catalyst for the 4-nitrophenol (4-NP) reduction reaction by sodium borohydride (NaBH4), they exhibited extremely high catalytic activity and excellent recyclability. These results demonstrated that the highly porous microspheres have very high porosity, huge surface area per unit volume, and good chemical stability, indicating their great potentials as a supporting material for practical applications in catalysis.