Adhesion of alumina surfaces through confined water layers containing various molecules

When two surfaces confine water layers between them at the nanoscale, the behaviour of these confined water molecules can deviate significantly from the behaviour of bulk water and it could reflect on the adhesion of such surfaces. Thus, the aim of this study is to assess the role of confined water layers on the adhesion of hydrophilic surfaces and how sensitive this adhesion is to the presence of contaminants. Our methodology used under water AFM force measurements with an alumina sputtered sphere-tipped cantilever and a flat alumina single crystal, then added fractions of ethanol, dimethylformamide, formamide, trimethylamine, and trehalose to water, as contaminants. Such solutions were designed to illuminate the influences of dielectric constant, molecular size, refractive index and number of hydrogen bonds from donors and acceptors of solutes to water. Apart from very dilute solutions of dimethylformamide, all solutions decreased the ability of confined water to give adhesion of the alumina surfaces. The predicted theoretical contribution of van der Waals and electrostatic forces was not observed when the contaminants distorted the way water organizes itself in confinement. The conclusion was that adhesion was sensitive mostly to hydrogen bonding network within water layers confined by the hydrophilic alumina surfaces

Irrigation water quality from wastewater reuse or groundwater sources: bridging the water–nutrient–food nexus

A field study is done to analyze the effects of water reuse for irrigation with a focus on seed germination, crop morphology, crop yield, nutritional values of edible parts, fertilizer reduction, and benefit–cost ratio. For the study, three different crops, Lablab bean, tomato, and chilli, are considered and every crop type is irrigated with groundwater (GW), diluted treated wastewater (DTWW), and treated wastewater (TWW). The study reveals that the DTWW is optimal for seed germination. Crops irrigated with the TWW have the highest morphological characteristics. Crop yield is highest for the TWW-irrigated Lablab bean and DTWW-irrigated tomato. Chilli remains unproductive until the end due to thermal stress. Nutritional values of the edible parts of the DTWW- and TWW-irrigated crops are lower than the GW-irrigated crops. Crops irrigated with the DTWW and TWW are applied with the reduced quantities of N, P and K fertilizers. Indeed, even when the dosages are low those crops are able to produce higher yields than the GW-irrigated crops which are applied with full fertilization. As the crop yield is high and fertilizer cost is less, the benefit–cost ratio is higher for water reuse irrigation than the GW irrigation. HIGHLIGHTS Water reuse, use of treated wastewater, for agriculture is one of the sustainable adaptations to combat the climate crisis.; This approach can ensure food security of people while conserving freshwater resources but the nutrient satiety of edible parts of crops irrigated with reclaimed water must be verified.; The study presented in this paper made an attempt to bridge the gap between the water–nutrient–food nexus of water reuse irrigation.

Role of pH of precursor solution in taming the material properties of spray pyrolysed SnS thin films

Samples were deposited using chemical spray pyrolysis technique by varying the pH of the starting precursor solution from 0.8 to 3.2. These samples were analyzed using X- ray diffraction, optical absorption spectroscopy, energy dispersive X-ray analysis, scanning electron microscopy, and electrical measurements in order to investigate the role of pH of the precursor solution on structural, morphological, electrical and optical properties of the SnS films. From the study we could optimize the pH of precursor solution required for the deposition of device quality SnS thin films. Resistivity of the films was brought down by three orders (to 6 × 10−2 Ω cm) along with enhancement in grain size as well as photosensitivity by optimizing the pH of the precursor solution alone. Band gap of the films could also be tailored by controlling the pH of the precursor solution

Solution-processed CuZn1−xAlxS2 : a new memory material with tuneable electrical bistability

CuZn1−xAlxS2 (CZAS) thin films deposited by the chemical spray pyrolysis (CSP) technique exhibit reversible electrical bistability in current–voltage measurements. The threshold voltage and current for switching can be tuned by the initial voltage applied to reset the device. X-ray diffraction and high-resolution transmission electron microscopy imaging show that the initial crystal structure of CZAS is similar to CuAlS2 with slightly expanded lattices due to the presence of Zn. The electrical memory effect in this material is observed only when both Zn and Al are present in the film, indicating that migration of interstitial Al towards the anode may be the origin of this memory effect

Defect levels in SnS thin films prepared using chemical spray pyrolysis

The origin of various defect levels in the SnS thin films deposited using chemical spray pyrolysis (CSP) technique has been explored in this manuscript, by employing low-temperature photoluminescence (PL) technique. Concentration of Sn in the samples was varied purposefully by ex situ diffusion in order to alter the defect levels. The acceptor level obtained at 0.22 eV from the Arrhenius plot, has been assigned as the defect level caused by the Sn vacancies present in the lattice. Two shallow donor levels are conclusively identified and their activation energies have been estimated. The present study could also unearth a trap level in the forbidden energy gap which was due to the oxygen contaminant occupied by the vacancy of Sn. This trap level could be removed by annealing the sample in vacuum or through the ex situ diffusion of Sn. Employing Kelvin probe force microscopy (KPFM), the work-function of SnS was obtained as 4.925 eV, from which the position of the Fermi level could be assigned. Based on the present work, an energy level scheme for SnS thin films is proposed outlying origin of various defect levels

Modulating the optical and electrical properties of all metal oxide solar cells through nanostructuring and ultrathin interfacial layers

The benefits and drawbacks of nanostructuring in all oxide ZnO/Cu2O solar cells were studied. The solar cells were fabricated on fluorine doped tin oxide substrates, with solution processed deposition methods. Both planar ZnO layer and Cu2O were deposited by electrodeposition while ZnO nanorods were grown by chemical bath deposition technique. It is shown that short circuit current (Jsc) of the devices increases with nanostructuring of ZnO due to electrical and optical gains. Despite improving the photocurrent, nanostructuring decreases the Voc of the device due to carrier recombination. The introduction of a thin TiO2 interfacial layer through atomic layer deposition was able to reduce the recombination

Photocarrier generation in CuxO thin films deposited by radio frequency sputtering

Copper oxides (CuxO) thin films were deposited using radio frequency (RF) sputtering on glass substrates. By tuning the argon (Ar) partial pressure during deposition, cuprous oxide (Cu2O), cupric oxide (CuO), or their mixed phase could be achieved. Drastic variations in the Hall mobility, hole density, and resistivity of the samples were observed due to the presence of different phases in the films. Kelvin probe studies indicate that the photo-generated carriers have lower recombination rate in pure Cu2O phase. This was further validated by transient absorption measurements, where the estimated carrier lifetime for Cu2O was much larger that other phases.Published versio