The growing demand for plasmonic metal nanohybrid structures for Surface-Enhanced Raman Scattering (SERS) and photocatalyst applications faces challenges such as the use of expensive noble metals, localised heating, reproducibility and complex synthesis routes. Here, we report an efficient, low-cost, in-situ, template-free method with only ∼ 2% Ag nanoparticles and ∼ 98% SnO2 quantum dots (QDs) for exceptional SERS and photocatalytic efficacy. It allows Rhodamine 6G detection down to 10-13 M with an enhancement factor of 0.94 × 1010. In addition to experimental characterisation using various techniques, COMSOL simulations and DFT calculations reveal a pronounced spatial extension of the electromagnetic field of Ag nanoparticles through the assembled SnO2 QDs, offering insight into charge transfer associated with the chemical enhancement and photocatalytic activities. Moreover, the Raman and PL investigations demonstrate efficient hot electron transfer from Ag to SnO2 QDs. The novel hybrid nanostructures with a minute amount of noble metal and abundant semiconductor nanoparticles pave the way for the development of highly cost-effective SERS substrates, photocatalysts, and other energy-harvesting applications.

Gold nanorods (GNRs) have become a key component in surface plasmon resonance (SPR)-based colorimetric methods for the detection of heavy metals in groundwater. However, sensitivity, selectivity, and performance in complex matrices limit the method's efficacy. Here, we report a detection-monitoring-removal (DMR) strategy for selective 50 mu g/L uranyl detection with a resolution of 7.5 ng/L using aminomethyl phosphonic acid (AMPA)-functionalized GNRs (f-GNRs). Density Functional Theory (DFT) elucidated the interaction between AMPA and GNRs, emphasizing the charge distribution characteristics. Experimental investigation using transmission electron microscopy (TEM), Raman spectroscopy, FTIR spectroscopy, and UV-vis spectroscopy unfurled the structure-property correlations of f-GNRs, and it offers substantial experimental support to theoretical findings. A mathematical modeling of an asymmetric plasmonic band using a skewed Lorentzian function reveals a linear relationship between the plasmonic band and uranium concentration, with an exceptional selectivity against metal ions such as Na, Mg, K, Ca, Cd, and Hg. Additionally, f-GNRs allowed U recovery with a loading capacity of 20 mu g/mL and validated detection against nuclear plant complaint simulated High-Level Waste (HLW). So, our approach employing f-GNRs provides an efficient strategy for the detection, separation, and extraction of uranyl ions from both groundwater and industrial effluents, offering a promising solution for environmental remediation.

Semiconducting nanoparticles (NPs) can act as remarkable photocatalysts for the remediation of polluted water. In this context, band gap engineered SnO2 quantum dot (QD) stabilized without any surfactant demonstrates exceptional photodegradation kinetics of non-biodegradable Methylene Blue (MB) dye due to the unique superoxide (O2 center dot-) radical generation. These QDs are also effective for the remediation of colorless explosive tri-nitro phenol (TNP) and antibiotic tetracycline (TC). The investigations by using Raman, X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM), UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) reveal distinctive structural and electronic properties of 2.5 nm QDs compared to 25 nm SnO2 NPs. The distinct photocatalytic activities of QDs are corroborated by photoluminescence (PL), photocurrent, Mott-Schottky (MS), and electron paramagnetic resonance (EPR) measurements. The scavenger study elucidates the generation of novel O2 center dot- by SnO2 QDs due to the band edge engineering that shifts conduction band minima beyond-0.33 eV as evident from the MS study. Thus, the QDs enabled O2 center dot- generation along with hydroxyl (center dot OH) radicals, allowing excellent photodegradation kinetics against aqueous pollutants for the first time. Therefore, the tailored structural and photo-physical properties as engineered for SnO2 QDs pave the way for the development of efficient photocatalysts for other metal oxides and sulfides.

Surface-enhanced Raman spectroscopy (SERS) is a label-free analytical technique for real-time trace-level detection. In this study, we report the formation of a monolayer SERS substrate of gold nanorods (GNRs) to detect hazardous and nonpermitted xanthene food additive dye, Rose Bengal (RB). The optimized aspect ratio of GNRs produced by a novel method is found to be an excellent candidate for the SERS substrate. Moreover, we demonstrate that a low wettability of nanometer-scale smooth (R-rms similar to 0.3 nm) substrate allows a tip-tip large-area assembly of GNRs. The electromagnetic field enhancement by the assembled GNRs is further revealed by the finite-difference time-domain calculation, which enables 0.1 pM detection of RB in an aqueous medium with an analytical enhancement factor of similar to 10(10). The large-area homogeneity of the SERS substrate is established through Raman imaging with a standard deviation of similar to 9.15%. The practical viability of the substrate is also upheld by ppb-level detection of RB in a commercial brown product.

Gd2O3 nanostructures were synthesized by hydrothermal method with five different reaction conditions (reac-tion temperatures: 130 degrees C, 180 degrees C and 230 degrees C and pH: 8, 10 and 13) and the effect on morphology of the Gd2O3 nanostructures is studied. Scanning electron microscopy results reveal that the morphology and the dimension of the nanostructures change with different preparation conditions and it ranges from thick ellipsoids to fine long nanorods. Fine long perfect nanorods are formed when the reaction temperature is 230 degrees C and pH is 8. Diffraction studies confirm that the crystal structure of the Gd2O3 samples is cubic. The change in the optical band gap of the Gd2O3 sample is consistent with the change in the dimension of the nanostructure. The quantum yield of Gd2O3 samples (2.74% to 6.84%) is found to be larger than the values reported for Gd2O3 samples with dimensions in quantum confinement range and in submicron range.

Nanostructured SnO2 emerged as an excellent photocatalytic material for wastewater treatment, but the limi-tation appears due to its high optical bandgap. Transition metal doping and composite are the common strategies to drag down its bandgap from UV to the visible region. In this manuscript, we highlight the surface defects induced photoreactivity of Fe-doped SnO2 in dye degradation. The native surface defects and the charge carrier concentrations have been found to diminish with the Fe incorporation in SnO2. The doping-induced surface hydroxyl groups are found to increase the charge transfer resistance. In subsequent, the combined effects of all decline the photoreactivity of Fe-doped SnO2. In light of the above, we demonstrate for the first time the pivotal role of native surface defects and surface chemistry in the photocatalysis process. This demonstration holds promise for other nanostructures where defects play a significant role.

Sustainable pollutants remedial is focussed by using surfactant-free ZnS nanoparticles (NPs) which are decorated with elemental-type sulfur defects (Es). Such functional ZnS NPs enable complete and rapid degradations of dye, drug (paracetamol, tetracycline), and explosive (trinitro-phenol) with UV to visible light irradiations. The evidences of Es formation are established by XPS, PL, and chemical reaction studies. HRTEM, XRD, EELS, UV-vis. absorption, PL, and Raman measurements have provided structural details of nanoparticles as well as confirmation on the critical role of Es towards the harvest of visible light. The highest carrier lifetime (5.8 mu Sec) of Es with a huge photocurrent (1.4 mu A/cm2) has revealed further insights of the exceptional degradation abilities of ZnS nanocatalysts of pollutants. The nanocatalyst decays pollutants completely under direct sunlight and shows -24 and -2.5 times better performances than the commercial ZnS and TiO2 (P25), respectively. Thus, impeccable photocatalysis efficacy of defects decorated ZnS nanocatalysts under a wide range of wavelengths of light is demonstrated. The study opens up further energy harvesting applications.

Adsorption and photocatalysis processes are of high significance for the remediation of toxic dyes in aquatic media.

Au nanorods (AuNRs) with a variety of aspect ratios (ARs) are used in surface-enhanced Raman spectroscopy (SERS), thermal therapy, and similar applications. In this study, we report a seed-mediated synthesis of AuNRs to cover different ARs in a single step with diluted HCl. This process ensures the realization of longitudinal surface plasmon resonance (LSPR) from the visible to the near-infrared region (similar to 650-1150 nm), improved uniformity with negligible by-products, and a low amount of surfactant. With no extra organic component, a halide (Cl) that allows for the unique control of the LSPR is highlighted along with other growth-defining reagents. A comparative SERS of rhodamine and photothermal examinations were performed for halide- and non-halidegrown AuNRs with an AR of similar to 7. An excellent enhancement factor (3 x 10(8)) was achieved for the halidegrown AuNRs and was verified by a finite-difference time-domain (FDTD) simulation. Halide-grown AuNRs with a width of similar to 5 nm demonstrated a highly improved plasmonic photothermal temperature of 45 degrees C, compared with that of 35 degrees C obtained from non-halide-grown AuNRs at a laser power density of only 1.1 W/cm(2). The superior efficiency and photothermal effects of halide-grown samples in SERS are among the best reported, and significantly expand the scope of their application.

The non-stick & foul release property of silicones was first reported in the early 1970s, with surface free energy of 22 – 24 dynes/cm offering a minimally adhesive surface to biological organisms. The superior antifouling performance of tri-butyl tin- self-polishing coatings TBT-SPC systems outshone all other antifouling formulations from 1970 to 1980s until environmental regulations warranted a total ban on the use of the TBT-SPC system. Foul release coatings (FRC’s) use hydrodynamic stress during navigation to minimize adhesion between fouling organisms and coating surfaces so that fouling can be removed. Addition of hydrophobic silicone oils along with other properties like low surface energy, elasticity and low glass transition temperature, low micro-roughness, attributed to the foul release property of siloxane polymers. Inhibition of fouling on FRC is dependent on several factors like chemical bonding of marine bio adhesives, electrostatic interactions, physical adsorptions between coatings and secreted bio adhesives, diffusion, penetration and interlocking of bio adhesives within the coating matrix. Foul release coatings are prone to biofouling and their fouling load decreases with an increase in hydrodynamic stress due to water flow. Fouling release occurs due to weak interfacial bond created by the organism’s cement and the coating surfaces as a result of low surface free energy (SFE) and cohesive failure of bio adhesives occurs due to shear forces created by flowing water across the coatings. Even though FRC has been shown to be eco-friendly & reduce drag they have many drawbacks viz: weak adhesion strength between coating and substrate, weak mechanical properties, poor AF performance under static conditions, inefficient against diatom and bacterial slimes. Bacterial and diatom biofilms on FRC’s increase frictional resistance reduce drag reduction and fuel savings. To improve the biofouling resistance of FRC, several approaches like amphiphiles, zwitterions, quaternary ammonium salts (QAs), and metal oxide nanoparticles have been investigated. PEG-based amphiphiles is one such example where findings have translated into a commercial paint Intersleek 1100SR and HempasilX3 formulations which have been reported to offer better fouling release of barnacles and diatoms. Surface chemistry, mechanical property, binding to substrates, and durability are vital factors in designing modern-day antifouling coatings and fouling resistance is a ubiquitous parameter in consideration. This review reports the advancements and modifications to the siloxane backbone by each of these parameters which have enabled in development of superior and environmentally benign foul release coatings.

The predominant type of defect that are created by ion/neutron irradiation, in oxide nuclear fuel materials like thoria, is oxygen vacancy. In the present study, the effect of O-vacancies on the f-occupancy of thorium is studied using experiments and density functional theory (DFT) calculations. Thoria samples are irradiated with low energy (100 keV He+) and high energy (100 MeV Ag+) ions and the effects are characterized with electron energy loss spectroscopy (EELS). Ion irradiation induced crater formation and annealing of craters are observed under scanning electron microscopy, and the crater formation is due to the deposition of large electronic energy density (similar to 20 keV/nm(3)). The branching ratio of the N 45 edges and the expectation values of the 5f spin-orbit interaction per core hole (< w(100)> /n(h)) clearly reveal that there is a transition in the f electron occupancy upon ion irradiation, towards that of atomic thorium. The electron charge density difference, calculated from DFT calculations, also support the experimental observations. (c) 2022 Elsevier B.V. All rights reserved.

Increased adhesion and biofilm formation by marine microalgae as well as inhibition of settlement of invertebrate larval forms on polydimethylsiloxane (PDMS) foul release coatings is a challenge to overcome. Copper oxide nanoparticles (CuO-NP) were synthesized by a wet chemical precipitation route and incorporated into PDMS foul release surfaces to improve its anti-microfouling nature. In situ antifouling performance of PDMS-CuO nanocomposite (NC) was evaluated in coastal waters and compared with plain PDMS surface. Adhesion and settlement of microalgae and macrofoulers and their succession were monitored for 7 and 90 days respectively. Plain PDMS surfaces were abundantly colonized by microalgae (1.3 x 103 cm-2), wherein significant (p < 0.05) reduction (1.76 x 102) was observed with PDMS-CuO NC. In addition, CuO reinforcement significantly (p < 0.05) reduced the biofouling load and surface area coverage upto 1.6 +/- 0.22 Kg m- 2 90 day-1 and 27.5 +/- 4.5% respectively, whereas plain PDMS surfaces experienced 10.6 +/- 1.5 Kg m- 2 90 day- 1 and 89.6 +/- 7.96% respectively. Incorporation of CuO nanoparticles as nanofillers into PDMS matrix offers a promising antifouling alternative to inhibit algal fouling as well as larval settlement by imparting toxicity at the surface through release of metal ions.

Polydimethyl siloxane (PDMS) CuO nanocomposites (NCs) were prepared using plain CuO and cetyltrimethyl ammonium bromide (CTAB) capped (0.05 & 1.0M) CuO nanoparticles as nanofillers. Incorporation of plain CuO and CuO-1M capped NP as nanofillers into PDMS altered their surface roughness and imparted biocidal activity by release of metal ions. CTAB capping increased the zeta potential of synthesized nanoparticles with 0.05M CTAB yielding monodispersed CuO-NP with enhanced broad spectrum antifouling activity in PDMS matrix. Nanocomposites were tested for their efficacy against inhibition of bacterial (in vitro) and diatom adhesion (in situ) in laboratory and coastal waters respectively. PDMS-CuO-CTAB (0.05M) capped nanoparticles showed significant (p<0.05) antibiofilm property against Staphylococcus lentus and Vibrio natriegens. Diatoms extensively colonized plain PDMS surfaces (1.2 x 10(3) cm (-2)), whereas PDMS-CuO, PDMS-CuO-0.05M CTAB, PDMS-CuO-1M CTAB NCs showed 1.20 x 103, 4.86 x 10(2) and 5.82 x 10(2) cells cm (-2) respectively. Field exposure trials showed reduction in fouling biomass from 9 Kg m (-2) (on plain PDMS) to 0.6 Kg m-2 on PDMS-CuO (0.05M CTAB) NC after 90 days of exposure in coastal waters. Percentage surface area coverage of fouling organisms also reduced significantly (p<0.05) from 98.3 +/- 0.6% on plain PDMS to 36.8 +/- 2.34% on PDMS-CuO-(0.05M CTAB) nanocomposite. Overall, PDMS-CuO-(0.05M CTAB) nanocomposite exhibited broad spectrum antifouling activity against different levels of fouling organisms and offers a potential antifouling surface.

Energy-efficient synthesized ZnS QDs with unique visible range absorption through defects show the best photocatalytic activity under UV light and best degradation under visible light.

The effects of two prominent copper oxide nanoparticles (CuO-NP and Cu2O-NP), with the oxidation state of Cu++ (cupric) and Cu+ (cuprous), on Candida albicans were evaluated. CuO-NP and Cu2O-NP were synthesized and characterized by XRD, FESEM, HR-TEM and Zeta potential. At sub-MIC (50 mu g ml(-1)), both cupric and cuprous oxide NPs prevented yeast-to-hyphae switching and wrinkling behaviour in C. albicans. The mechanism for the antifungal action of the two NPs differed; CuO-NP significantly elicited reactive oxygen species, whereas membrane damage was more pronounced with Cu2O-NP. Real time PCR analysis revealed that CuO-NP suppressed the morphological switching of yeast-to-hyphae by down-regulating cph1, hst7 and ras1 and by up-regulation of the negative regulator tup1. In comparison, Cu2O-NP resulted in down-regulation of ras1 and up-regulation of the negative regulators nrg1 and tup1. Between the two NPs, CuO exhibited increased antifungal activity due to its stable oxidation state (Cu++) and its smaller dimensions compared with Cu2O-NP.