Green synthesize of copper nanoparticles on the cotton fabric as a self-regenerating and high-efficient plasmonic solar evaporator.

Harvesting solar energy, as a clean and abundant resource, in the photothermal process, is the winning point of solar steam generation (SSG) systems. Herein, copper plasmonic nanoparticles were synthesized through a green method via red sanders extraction on the cotton fabric as the reducing matrix. The prepared fabrics were analyzed using FESEM, EDS, XRD, PL, Raman, and contact angle. The treated fabric on the stitched PU foam with cotton yarns with bio-inspired jellyfish structure was used for heat localization and water transmission, simultaneously. The evaporation rate, enhancement, and conversion efficiency of the plasmonic SSG were 1.73 kg m-2 h-1, 179%, and ~ 98%, under one sun irradiation, respectively. The quality of the collected water was investigated via induced coupled plasma which presents the proper solar desalination (> 99.83% for filtration of Na+ ion). Regenerating features of the treated fabric along with the simple and cost-effective preparation method promises viable aspects of our system for large-scale applications.

Tunable Gain SnS2/InSe Van der Waals Heterostructure Photodetector.

Due to the favorable properties of two-dimensional materials such as SnS2, with an energy gap in the visible light spectrum, and InSe, with high electron mobility, the combination of them can create a novel platform for electronic and optical devices. Herein, we study a tunable gain SnS2/InSe Van der Waals heterostructure photodetector. SnS2 crystals were synthesized by chemical vapor transport method and characterized using X-ray diffraction and Raman spectroscopy. The exfoliated SnS2 and InSe layers were transferred on the substrate. This photodetector presents photoresponsivity from 14 mA/W up to 740 mA/W and detectivity from 2.2 × 108 Jones up to 3.35 × 109 Jones by gate modulation from 0 V to +70 V. Light absorption and the charge carrier generation mechanism were studied by the Silvaco TCAD software and the results were confirmed by our experimental observations. The rather high responsivity and visible spectrum response makes the SnS2/InSe heterojunction a potential candidate for commercial visible image sensors.

Design of effective self-powered SnS2/halide perovskite photo-detection system based on triboelectric nanogenerator by regarding circuit impedance.

Self-powered detectors based on triboelectric nanogenerators (TENG) have been considered because of their capability to convert ambient mechanical energy to electrical out-put signal, instead of conventional usage of electrochemical batteries as power sources. In this regard, the self-powered photodetectors have been designed through totally two lay out called passive and active circuit. in former model, impedance matching between the TENG and the resistance of the circuit's elements is crucial, which is not investigated systematically till now. In this paper, a cost effective novel planar photodetector (PD) based on heterojunction of SnS2 sheets and Cs0.05(FA0.83 MA0.17)0.95Pb(I0.83Br0.17)3 three cationic lead iodide based perovskite (PVK) layer fabricated which powered by graphene oxide (GO) paper and Kapton based contact-separated TENG (CS-TENG). To achieve the high performance of this device, the proper range of the load resistances in the circuit regards to TENG's characterization has been studied. In the next steps, the integrated self-powered photo-detection system was designed by applying Kapton/FTO and hand/FTO TENG, separately, in the proposed impedance matching circuit. The calculated D* of integrated self-powered SnS2/PVK supplied by tapping the Kapton and hand on FTO is 2.83 × 1010 and 1.10 × 1013 Jones under the 10 mW/cm2 of white light intensity, the investigations determine that for designing significate performance of self-powered PD supplied by TENG, the existence of the load resistance with the well match amount to the utilized TENG is crucial. Our results which can be generalized to other types of passive self-powered sensors, are substantial to both academia and industry concepts.

Enhanced Photoresponse and Wavelength Selectivity by SILAR-Coated Quantum Dots on Two-Dimensional WSe2 Crystals.

High-performance photodetectors play crucial roles as an essential tool in many fields of science and technology, such as photonics, imaging, spectroscopy, and data communications. Demands for desired efficiency and low-cost new photodetectors through facile manufacturing methods have become a long-standing challenge. We used a simple successive ionic layer adsorption and reaction (SILAR) method to synthesize CdS, CdSe, and PbS nanoparticles directly grown on WSe2 crystalline flakes. In addition to the excellent wavelength selectivity for (30 nm) CdS, (30 nm) CdSe, and (6 nm) PbS/WSe2 heterostructures, the hybrid devices presented an efficient photodetector with a photoresponsivity of 48.72 A/W, a quantum efficiency of 71%, and a response time of 2.5-3.5 ms. Considering the energy band bending structure and numerical simulation data, the electric field distribution at interfaces and photocarrier generation/recombination rates have been studied. The introduced fabrication strategy is fully compatible with the semiconductor industry process, and it can be used as a novel method for fabricating wavelength-tunable and high-performance photodetectors toward innovative optoelectronic applications.

Urchin-like hierarchical ruthenium cobalt oxide nanosheets on Ti3C2Tx MXene as a binder-free bifunctional electrode for overall water splitting and supercapacitors.

Synthesizing efficient electrode materials for water splitting and supercapacitors is essential for developing clean electrochemical energy conversion/storage devices. In the present work, we report the construction of a ruthenium cobalt oxide (RuCo2O4)/Ti3C2Tx MXene hybrid by electrophoretic deposition of Ti3C2Tx MXene on nickel foam (NF) followed by RuCo2O4 nanostructure growth through an electrodeposition process. Owing to the strong interactions between RuCo2O4 and Ti3C2Tx sheets, which are verified by density functional theory (DFT)-based simulations, RuCo2O4/Ti3C2Tx MXene@NF can serve as a bifunctional electrode for both water splitting and supercapacitor applications. This electrode exhibits outstanding electrocatalytic activity with low overpotentials of 170 and 68 mV at 100 A m-2 toward the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The RuCo2O4/Ti3C2Tx MXene@NF-based alkaline water-splitting cell only requires 1.62 V to achieve a current density of 100 A m-2, which is much better than that of RuO2@NF and Pt/C@NF-assembled cells (1.75 V@100 A m-2). The symmetric supercapacitor (SSC)-assembled electrode displays a high specific capacitance of 229 F g-1 at 3 A g-1. The experimental results, complemented with theoretical insights, provide an effective strategy to prepare multifunctional materials for electrocatalysis and energy storage applications.

Ultrafast and stable planar photodetector based on SnS2 nanosheets/perovskite structure.

Two-dimensional (2D) transition metal dichalcogenides are promising candidates of photodetectors where they are commonly grown parallel to the substrate due to their 2D characteristics in micrometer scales from exfoliation of bulk crystals or through high temperature chemical vapor deposition (CVD) methods. In this study, semi-hexagonal vertical nanosheets of SnS2 layered have been fabricated on FTO substrate without using Sn source through CVD method at relatively low temperature (500 °C). Due to exceptional band alignment of triple cation lead perovskite (TCLP) with semi-hexagonal SnS2 nanosheets, an improved photodetector has been fabricated. This type of photodetectors fabricated through lithography-free and electrodes metallization free approach with remarkable fast response (20.7 µs/31.4 µs as rising /falling times), showed high photoresponsivity, external quantum efficiency and detectivity of 1.84 AW-1, 513% and 1.69 × 1011, respectively under illumination of incident light with wavelength of 445 nm. The stability of the photodetectors has been studied utilizing a protective PMMA layer on the perovskite layer in 100% humidity. The introduced growth and fabrication process of the planar photodetector, including one/two dimensional interface through the edges/basal planes of layered materials with perovskite film, paves a way for the large scale, cost-effective and high-performance optoelectronic devices.

High flux and complete dyes removal from water by reduced graphene oxide laminate on Poly Vinylidene Fluoride/graphene oxide membranes.

Dyes molecules are the most common pollutants of wastewater in the environment from the textile industry to numbers of technologies include dyeing, printing, and painting procedures. Among membrane-based separation approaches as established methods in the water treatment industry, polymers attracted massive attention in the production of membranes due to their low cost and high-performance filtration of pollutants. However, hydrophobicity and low speed of filtration along with limited decontamination performance against some of the dyes, demand new approaches and membranes to overcome drawbacks points. Herein, a new design introduced including a support layer made by Poly Vinylidene Fluoride (PVDF)/Graphene Oxide (PGO) composite membrane via immersion precipitation process and a thin layer (≤100 nm) of reduced graphene oxide (rGO) deposited (as an active layer) through a simple vacuum filtration method. It has been observed that the presence of the GO sheets in the PGO composite improved the hydrophilicity of the membrane, water flux (from ~90 L m-2 h-1 bar-1 in pristine PVDF to ~1690 L m-2 h-1 bar-1 in PGO), and anti-fouling property. By deposition of rGO laminate on PGO support, dyes separation as high as ~99% can be achieved for most of the cationic and anionic dyes due to electrostatic adsorption, π-π interactions and molecular sieving. This approach opens new insight on hybrid designs for graphene-polymers based membrane toward efficient and fast removal of pollutants from wastewater.

Visualising structural modification of patterned graphene nanoribbons using tip-enhanced Raman spectroscopy.

Graphene nanoribbons (GNRs) fabricated using electron beam lithography are investigated using tip-enhanced Raman spectroscopy (TERS) with a spatial resolution of 5 nm under ambient conditions. High-resolution TERS imaging reveals a structurally modified 5-10 nm strip of disordered graphene at the edge of the GNRs. Furthermore, hyperspectral TERS imaging discovers the presence of nanoscale organic contaminants on the GNRs. These results pave the way for nanoscale chemical and structural characterisation of graphene-based devices using TERS.

Plasmonic enhancement of photocurrent generation in two-dimensional heterostructure of WSe2/MoS2.

Enhancing the photoresponse of single-layered semiconductor materials is a challenge for high-performance photodetectors due to atomically thickness and limited quantum efficiency of these devices. Band engineering in heterostructure of transition metal chalcogenides (TMDs) can sort out part of this challenge. Here, we address this issue by utilizing the plasmonics phenomenon to enrich the optoelectronics property of the WSe2/MoS2heterojunction and further enhancement of photoresponse. The introduced approach presents a contamination-free, tunable and efficient way to improve light interactions with heterojunction devices. The results showed a 3600-fold enhancement in photoresponsivity and a 46-fold increase in external quantum efficiency (549%) along with a fast photoresponse time (~2µs) and light polarization dependence. This improvement may assign to multiple light scatterings by the Au nanoarrays and creation of strong local electrical fields (hot spots) at the interfaces of the gold nanoarrays and the TMDs heterostructure. The high-energy electrons (hot electrons) originating from hot spots surmount easily to conduction bands of heterojunction which is leading to a remarkable enhancement of photocurrent. The plasmons assisted photoresponse strategy can be easily matched with the semiconductor industry to boost the performance of optoelectronics devices for practical applications.

Mechanical hydrolysis imparts self-destruction of water molecules under steric confinement.

Decoding behavioral aspects associated with the water molecules in confined spaces such as an interlayer space of two-dimensional nanosheets is key for the fundamental understanding of water-matter interactions and identifying unexpected phenomena of water molecules in chemistry and physics. Although numerous studies have been conducted on the behavior of water molecules in confined spaces, their reach stops at the properties of the planar ice-like formation, where van der Waals interactions are the predominant interactions and many questions on the confined space such as the possibility of electron exchange and excitation state remain unsettled. We used density functional theory and reactive molecular dynamics to reveal orbital overlap and induction bonding between water molecules and graphene sheets under much less pressure than graphene fractures. Our study demonstrates high amounts of charge being transferred between water and the graphene sheets, as the interlayer space becomes smaller. As a result, the inner face of the graphene nanosheets is functionalized with hydroxyl and epoxy functional groups while released hydrogen in the form of protons either stays still or traverses a short distance inside the confined space via the Grotthuss mechanism. We found signatures of a new hydrolysis mechanism in the water molecules, i.e. mechanical hydrolysis, presumably responsible for relieving water from extremely confined conditions. This phenomenon where water reacts under extreme confinement by disintegration rather than forming ice-like structures is observed for the first time, illustrating the prospect of treating ultrafine porous nanostructures as a driver for water splitting and material functionalization, potentially impacting the modern design of nanofilters, nanochannels, nano-capacitators, sensors, and so on.

A graphene/TiS3 heterojunction for resistive sensing of polar vapors at room temperature.

The room temperature polar vapor sensing behavior of a graphene-TiS3 heterojunction material and TiS3 nanoribbons is described. The nanoribbons were synthesized via chemical vapor transport (CVT) and their structure was investigated by scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Raman and Fourier transform infrared spectroscopies. The gas sensing performance was assessed by following the changes in their resistivities. Sensing devices were fabricated with gold contacts and with lithographically patterned graphene (Gr) electrodes in a heterojunction Gr-TiS3-Gr. The gold contacted TiS3 device has a rather linear I-V behavior while the Gr-TiS3-Gr heterojunction forms a contact with a higher Schottky barrier (250 meV). The I-V responses of the sensors were recorded at room temperature at a relative humidity of 55% and for different ethanol vapor concentrations (varying from 2 to 20 ppm). The plots indicate an increase in the resistance of Gr-TiS3-Gr due to adsorption of water and ethanol with a relatively high sensing response (~495% at 2 ppm). The results reveal that stable responses to 2 ppm concentrations of ethanol are achieved at room temperature. The response and recovery times are around 8 s and 72 s, respectively. Weaker responses are obtained for methanol and acetone. Graphical abstract Schematic representation of resistance sensor for detection of low concentration of ethanol vapor. The graphene and TiS3 nanoribbons were synthesized using chemical vapor deposition and chemical vapor transport technique respectively. The 2D graphene/TiS3 heterojunction device was fabricated to make a high response sensor due to their synergy effect.

A selective chemiresistive sensor for the cancer-related volatile organic compound hexanal by using molecularly imprinted polymers and multiwalled carbon nanotubes.

A chemiresistive sensor is described for the lung cancer biomarker hexanal. A composite consisting of molecularly imprinted polymer nanoparticles and multiwalled carbon nanotubes was used in the sensor that is typically operated at a voltage of 4 V and is capable of selectively sensing gaseous hexanal at room temperature. It works in the 10 to 200 ppm concentration range and has a 10 ppm detection limit (at S/N = 3). The sensor signal recovers to a value close to its starting value without the need for heating even after exposure to relatively high levels of hexanal. Graphical abstract Schematic presentation of a chemiresistive sensor for detection of hexanal, a cancer biomarker. The hexanal-imprinted polymeric nanoparticles were synthesized, mixed with multiwalled carbon nanotubes and coated on the surface of an interdigitated electrode to produce a nanocomposite chemiresistor gas sensor for hexanal.