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Incautious discharge of organic dyes such as methyl orange (MO) has produced serious pollution to the environment, calling for the efficient techniques to remove them with retaining the green world. The photo-catalytic degradation of organic dyes is promising among the developed techniques. Thus, a strategy based on transpiration-prompted photocatalytic degradation of dye pollutant under sunlight is put forward. Aniline (ANI) is graft-polymerized onto poly(acrylamide-co-N-4-aminophenylacrylamide) (PAAm) cryogel embedded with gold nanoparticles (AuNPs, diameter: 4–10 nm). The obtained cryogels integrated with AuNPs and PANI inside PAAm matrix (AuNP@PAAm-g-PANI) have been structurally explored based on the chemical composition and the phase/porous morphology. SEM and TEM observation shows that PANI and AuNPs are uniformly distributed in PAAm matrix. Since the macro-porosity of cryogel, hydrophilicity of PAAm and photo-thermal activity of PANI, PAAm-g-PANI cryogels without AuNPs can have a photo-thermal evaporation rate of water at 1.63 kg·m−2·h−1. As a comparison, AuNP@PAAm-g-PANI cryogels with AuNPs exhibit higher one at 2.20 kg·m−2·h−1, suggesting the promotion of AuNPs to photo-thermal evaporation. Meanwhile, PANI appreciatively assists AuNPs to display higher catalytic ability for the oxidative degradation of MO. Therefore, the removal of MO from water is obviously prompted by the water transpiration under sunlight with AuNP@PAAm-g-PANI cryogels, whose rate constant can reach to 0.320 h−1, being three folds of that for the sole absorption of MO. This transpiration-prompted photocatalytic degradation provides a fascinating route to eliminate organic pollutants and obtain pure water from wastewater simultaneously with sustainable sunlight energy. [ABSTRACT FROM AUTHOR]

Summary: There have been tremendous efforts made to investigate various materials to enhance the electrical performance of triboelectric nanogenerators (TENGs) but there is still demand for some techniques to further enhance the performance of tribomaterials. Therefore, we fabricated a bimetallic hybrid cryogel via cheap and facile UV‐radiation as well as in situ reduction method. Fabricated TENG device made up of porous hybrid bimetallic cryogel film containing silver and gold nanoparticles as tribopositive material and poly dimethyl siloxane (PDMS) as a tribonegative layer with dimension of 1 × 2 cm2 has the ability to produced output voltage of 262.14 V with current density of 27.52 mA/m2 and 7.44 W/m2 peak power density, which was sufficient to light up more than 120 white light emitting‐diodes (LEDs). Porous and rough structure, interaction of nanoparticles was the reason behind the performance enhancement of tribopositive material. Thus, this study introduces a very stable and easily synthesized bimetallic hybrid cryogel as a tribopositive material to enhance the performance of tribomaterials to design high performance TENG devices. [ABSTRACT FROM AUTHOR]

The development of robust materials possessing simultaneously antibacterial and catalytic activities for the reduction and removal of organic pollutants from wastewater with enhanced efficacy has received unwavering interest. Herein, highly porous and thermo-responsive cryogels of poly(N -isopropylacrylamide-co-acryamido-2-methylpropane sulfonic acid) have been fabricated via redox-initiated cryo-polymerization. Silver/gold bimetallic nanoparticles were introduced into a bare cryogel through thermal reduction of metal salts. The fabricated bare cryogels and bimetallic integrated cryogel were confirmed with different techniques including fourier transform infrared spectroscopy. The crystallinity of bare cryogels and bimetallic nanoparticles inside cryogel was examined by using powder X-ray diffraction. Thermo-gravimetric analysis confirmed that bimetallic nanoparticle loaded cryogels were thermally more stable than bare cryogels. The macro-porosity of cryogels before and after loading bimetallic nanoparticles were studied by using scanning electron microscopy. Energy dispersive X-ray and X-ray photoelectron spectroscopy were implemented, confirming the presence of metal elements in the synthesized bimetallic hybrid cryogel. Furthermore, the uniform distribution of silver and gold nanoparticles in cryogel was examined with transmission electron microscopy. The fabricated bimetallic nanoparticle loaded cryogel exhibited high antibacterial activities against E. coli and S. aureus as well as the good catalytic capacity for the rapid reduction of p- nitrophenol and rhodamine B. Catalytic activity was also examined at various temperatures, different pH values and catalyst amounts. The activation energy (E a = 34.41 kJ mol-1), enthalpy change (Δ H = - 31.92 kJ mol-1) and entropy change (Δ S = −145.19 J mol-1 k-1) of catalytic reduction activation were determined using Arrhenius and Eyring equations. The catalytic performance of bimetallic nanoparticle loaded cryogel was also examined in pure water and tap water. The fabricated bimetallic catalyst was highly stable up to five consecutive cycles without any change in their catalytic performance. [Display omitted] • Highly porous and thermo-responsive cryogels were fabricated. • Cryo-polymerization was followed for such fabrication. • Ag/Au nanoparticles were introduced into cryogels via thermal reduction. • The fabricated bimetallic cryogel exhibited antibacterial and catalytic activities. • This bimetallic cryogel had the ability to remove organic pollutants. [ABSTRACT FROM AUTHOR]

Narrowly distributed poly(l-lysine-b-N-isopropylacrylamide) (PLL-b-PNIPAM) was prepared through ring-opening polymerization of ε-benzyloxycarbonyl-l-lysine N-carboxy-α-amino anhydride and atom transfer radical polymerization of NIPAM, followed with the removal of ε-benzyloxycarbonyl group. Then gold nanoparticles (AuNPs) grafted with PLL-b-PNIPAM (PNIPAM-PLL-AuNPs) were obtained by the reduction of chloroauric acid with sodium citrate in the presence of PLL-b-PNIPAM. PNIPAM-PLL-AuNPs and its precursors were thoroughly characterized by proton magnetic resonance spectroscope, Fourier transform infrared spectroscope, UV-vis spectroscope, transmission electron microscopy, dynamic light scattering, thermogravimetric analysis, and circular dichroism. The obtained PNIPAM-PLL-AuNPs exhibited high colloid stability even at strong alkaline (pH = 12) and acidic (pH = 2) conditions. The thermal and pH dual-responsive behaviors of the grafting PLL-b-PNIPAM chains was observed to be affected by AuNPs, while not for the secondary structure of PLL chains. Correspondingly, the surface plasmon resonance (SPR) of AuNPs was found to be sensitive to both pH value and temperature. A blue shift in the SPR happened both with increasing pH value and increasing temperature. The stimuli-response was reversible in heating-cooling cycles. The gold nanoparticles with both pH and temperature response may have potential applications in biomedical areas and biosensors. [ABSTRACT FROM AUTHOR]

A nanoreactor with temperature-responsive poly(N-isopopylacrylamide) (PNIPAM) coated on the external poremouth ofmesoporous silica hollow spheres and Au nanoparticles at the internalpore mouth were fabricated. Such spatial separation allows both Aunanoparticles and PNIPAM to function without interfering with eachother. Transmission electron microscopy (TEM), thermogravimetric analysis(TGA), Fourier transform infrared (FTIR) spectra, and temperature-dependentoptical transmittance curves demonstrate successful grafting of PNIPAM.This nanoreactor shows repeated on/off catalytic activity switchedby temperature control. It shows excellent catalytic activity toward4-nitrophenol (4-NP) reduction at 30 °C [below lower criticalsolution temperature (LCST)of PNIPAM] with a turnover frequency (TOF) of 14.8 h–1. However, when the temperature was 50 °C (above LCST), theTOF dropped to 2.4 h–1. Kinetic studies indicatedthat diffusion into the mesopores of the catalyst was the key factor,and the temperature-responsive behavior of PNIPAM was able to controlthis diffusion. [ABSTRACT FROM AUTHOR]