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Context: With the union of machine learning (ML) and quantum chemistry, amid the debate between machine-learned functionals and human-designed functionals in density functional theory (DFT), this paper aims to demonstrate the generation of potential energy surfaces using computations with machine-learned density functional approximation (ML-DFA). A recent research trend is the application of ML in quantum sciences in the design of density functionals such as DeepMind's Deep Learning model (DeepMind21, DM21). Though science reported the state-of-the-art performance of DM21, the opportunity to utilize DeepMind's pretrained DM21 neural networks in computations in quantum chemistry has not yet been tapped. So far in the literature, the Deep Learning density functionals (DM21) have not been applied to generate potential energy surfaces. While the superior accuracy of DM21 has been reported, there is still a scarcity of publications that apply DM21 in calculations in the field. In this context, for the first time in literature, neural density functionals inferring 2D potential energy surfaces (ML-DFA-PES) based on machine-learned DFA-based computational method is contributed in this paper. This paper reports the ML-DFA-generated PES for C4H8, H2O, H2, and H2+ by employing a pretrained DM21m TensorFlow model with cc-pVDZ basis set. In addition, we also analyze the long-range behavior of DM21 based PES to investigate the ability to describe a system at long ranges. Furthermore, we compare PES diagrams from DM21 with popular DFT functionals (b3lyp/ PW6B95) and CCSD(T). Methods: In this method, 2D potential energy surfaces are obtained using a method that relies upon the neural network's ability to accurately learn the mapping between 3D electron density and exchange–correlation potential. By inserting Deep Learning inference in DFT with a pretrained neural network, self-consistent field (SCF) energy at different geometries along the coordinates of interest is computed, and then, potential energy surfaces are plotted. In this method, first, the electron density is computed mathematically, and this computed 3D electron density is used as a ML feature vector to predict the exchange correlation potential as a ML inference computed by a forward pass of pre-trained DM21 TensorFlow computational graph, followed by the computation of self-consistent field energy at multiple geometries, and then, SCF energies at different bond lengths/angles are plotted as 2D PES. We implement this in a python source code using frameworks such as PySCF and DM21. This paper contributes this implementation in open source. The source code and DM21-DFA-based PES are contributed at https://sites.google.com/view/MLfunctionals-DeepMind-PES. [ABSTRACT FROM AUTHOR]

The excessive use of the antibiotics like norfloxacin and their residue is a serious threat to the environment. Although photocatalysis method of removing antibiotics is considered as an efficient method, again the materials used for the above purpose should be environmentally benign and earth abundant in nature. Hence exploration of new materials and enhancing the efficiency of materials for photocatalytic degradation of the above antibiotic become an important topic of investigation. Inducing oxygen vacancies in an environment-benign compound like MgMn2O4 through low concentration of transition metal ion doping and their advantageous changes in optical properties are favorable for the photocatalytic application. In this regard, the changes in the structural and optical properties of the MgMn2O4 compound, by doping with Ni/Co ions is explored. It is found that the nickel doping shows a high photocatalytic degradation of norfloxacin as 90–95% within 90 min under the irradiation of UV–Vis light, which is higher than the bare and cobalt ion-doped compound. This is due to the more number of oxygen vacancies as analyzed from XPS, high light absorption, and more charge separation retention characteristics, as per UV–VIS and PL studies, respectively. The MgNi0.5Mn1.5O4 compound shows a high rate constant value of 9.25 × 10–4 M−1 s−1 and high reusability up to four cycles and could be utilized as the efficient photocatalytic materials for wastewater remediation. [ABSTRACT FROM AUTHOR]

Utilization of environmentally friendly and effective synthesis methods to fabricate visible light responsive photocatalysts with impressive catalytic performance is desirable in photocatalytic water treatment. Herein, we employed the powerful and environmentally benign ultrasonic synthesis to hybridize hydrothermally prepared NiNb2O6 with varying amounts of RGO (5, 10 and 15 wt%) obtained via a modified Hummers' method. The samples were characterized extensively using analytical techniques such as XRD, SEM-EDX, TEM, UV-Vis DRS, PL, XPS, M-S and EIS, and subsequently employed for the degradation of doxycycline (DOX) and tetracycline hydrochloride (TC) in water under visible light exposure. The binary nanocomposites displayed enhanced activity compared to NiNb2O6, with the highest activity attained over the 10 wt% RGO sample (NiNb2O6/10 wt% RGO) which achieved 89.2% and 94.1% DOX and TC removal in 80 min, respectively. This was ascribed to improved visible light response, and charge separation and transfer. Furthermore, the influence of pH, pollutant initial concentration and photocatalyst dose was investigated. The hydroxyl radicals and holes were identified as the predominant reactive species responsible for degradation of both DOX and TC. Finally, a feasible charge transfer pathway was proposed to explain the formation of the reactive species and GC-MS analysis was employed to track the degradation route of DOX. This work presents a simple and effective route for coupling RGO and NiNb2O6 nanoparticles for antibiotic pollution abatement which is currently a major environmental concern. [ABSTRACT FROM AUTHOR]

The exploitation of visible light active photocatalysts for the removal of various pollutants has been given tremendous consideration in water and wastewater treatment. Herein, a novel In2S3/CeO2 n–n type heterojunction photocatalyst was successfully synthesized by a two-step method involving hydrothermal synthesis and subsequent ultrasonic treatment to couple In2S3 with CeO2 (5, 10 and 15 wt%). The as-synthesized samples were characterized extensively using analytical techniques such as XRD, UV-vis-DRS, SEM-EDX, TEM, BET, PL, EIS and XPS to examine the chemical composition, phase structure, morphology and photo-chemical characteristics of the materials. Subsequently, the In2S3/CeO2 nanostructures were employed in the degradation of oxytetracycline (OTC) (10 mg L−1) and reduction of Cr(VI) (50 mg L−1) in aqueous solutions, upon exposure to visible light. Under optimised experimental conditions, the nanocomposite constituting 10 wt% CeO2 (In2S3/10 wt% CeO2) showed the highest activity, reaching 87.9% OTC degradation and 97.5% Cr(VI) reduction after 60 min and 40 min of visible light irradiation, respectively. The nature and contribution of active species in the photocatalytic process were revealed through radical scavenging studies. Finally, a plausible band structure, charge separation and transfer mechanism were crafted to illustrate the synergy between In2S3 and CeO2 which led to improved degradation kinetics. This work demonstrated a simple route for improving the visible light-mediated activity of In2S3 by coupling with CeO2 and the potential versatility of the composite material for the removal of both organic and inorganic pollutants from water. [ABSTRACT FROM AUTHOR]

Design and optimization of visible-light-driven photocatalysts for degradation of organic pollutants is an important step towards environmental decontamination. In this study, wolframite cerium tungstate (Ce2(WO4)3, (CW)) hybridized with g-C3N4 (CN) nanosheets was synthesized via a simple hydrothermal route followed by an ultrasound-assisted synthesis method. The prepared Ce2(WO4)3@ g-C3N4 (CW@CN) heterojunction was investigated for photocatalytic degradation of the antibiotic moxifloxacin (MXF) under visible light irradiation. Structural, morphological, and optical properties as well as chemical composition of the as-synthesized heterojunction were investigated by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) and photoluminescence (PL). MXF photocatalytic degradation by the binary nanostructure (Ce2(WO4)3@ g-C3N4) (94.1%) was the highest compared to g-C3N4 (53.6%) and Ce2(WO4)3 (46.4%). Such enhanced activity could be ascribed to efficient suppression of the charge carriers' recombination, leading to adequate formation of the reactive species responsible for MXF degradation. Furthermore, the Ce2(WO4)3@ g-C3N4 heterojunction showed remarkable stability over five consecutive cycles, with only 11.5% reduction after the 5th cycle. This work established the potential applicability of Ce2(WO4)3@ g-C3N4 nanostructures towards photocatalytic removal of MXF. [ABSTRACT FROM AUTHOR]

Development of novel Faradic electrode with excellent rate capability and long-lasting characteristics determines the performance of supercapacitor (SC) in current scenario. Rare-earth metal oxides have received considerable attention in SC domain with high volumetric energy density and capacitive performance. In this context, we have fabricated gadolinia/nickel sulphide nanocomposite via simple chemistry approach followed by two step hydrothermal method. Especially, the gadolinia/nickel sulphide nanocomposite synthesized in the current study offers high specific capacitance (354 F g−1 at a constant current density of 0.5 A g−1), low charge transfer resistance (6.37 Ω) and outstanding cycle life (1.3% loss capacitance loss even after 5000 continuous charge/discharge cycles). Such enduring energy characteristics of gadolinia based nanocomposite will create a huge impact in the future energy storage systems [ABSTRACT FROM AUTHOR]

In the present study, a gadolinium oxide (Gd2O3) nanorod was successfully synthesized by simple hydrothermal method for the photocatalytic degradation of chloramphenicol (CAP) drug under UV light illumination. Interestingly, the rod like morphology was observed from the TEM images with the particle size of 20 nm. The XRD results suggested that the high crystalline nature of the Gd2O3 nanorods with the crystalline size of 13 nm. The XPS results confirmed the formation of Gd2O3 nanorods and the oxidation states of different elements were addressed. The photocatalytic degradation of CAP was performed under ultra violet light illumination on Gd2O3 nanorods surfaces. The Gd2O3 nanorods were showed enhanced efficacy compared to the standard TiO2 under UV light illumination. The photocatalytic degradation results revealed that the drug was degraded within a short span of time. 50 mg of Gd2O3 nanorods and 20 mg/mL of drug concentration were the optimized condition for the effective photocatalytic degradation. The reactive oxidative species actively involved in the photodegradation of CAP was ·OH and up to 5th recycle the Gd2O3 nanorods were possessed excellent stability. [ABSTRACT FROM AUTHOR]

In this present work, we report a novel green synthesis of MoO3 nanorods (NRs) utilizing Abutilon Indicum (A. Indicum) plant extract, containing palmitric, linoleic, linolinic acids and their derivatives which might be acting as both reducing and stabilizing agents. The synthesized catalyst has been employed to reduce toxic Cr(VI) to Cr(III) in the aqueous solution which was continuously monitored by UV-Vis absorbance spectroscopy. The structural, optical and morphological characterizations are performed using PXRD, UV-DRS, PL, FESEM, TEM, FT-IR and EDAX. The optical properties were precisely investigated by calculating the Tauc's relation. The band gap of as synthesized MoO3 was found to be 2.57 eV (483 nm) which falls under visible region, thus catalyst can be activated under solar light which could be cost effective. Biologically synthesized MoO3 NRs showed highest activity, i.e., almost 99% toward reduction of Cr(VI) under solar light. In addition to this, the photo firmness and reusability test showed that the catalyst can be reused upto five cycles without waning its activity. [ABSTRACT FROM AUTHOR]

In this present scenario, for the first time, we propose a facile and simple wet chemical approach for the fabrication of two-dimensional (2D) cerium tungstate (CeW2O9;CeW) nanosheets and evaluated as an electrochemical sensor for the detection of nitrite ions. The successful formation of CeW2O9 nanosheets was confirmed by various physicochemical techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, Raman, Scanning electron microscope, Transmission electron microscope and Energy dispersive X-ray studies. The electrochemical properties of the CeW nanosheets were studied by using cyclic voltammograms (CV) and chronoamperometric techniques. As an electrochemical sensor, the CeW nanosheets modified glassy carbon electrode (GCE) showed superior electrocatalytic activity in the oxidation of nitrite in terms of higher anodic peak current and lower oxidation potential when compared with unmodified GCE. CeW nanosheets based electrochemical sensor has been fabricated which detect nitrite in wide linear response range, good sensitivity and very low detection limit of 0.02-986 μM, 2.85 μA μM−1 cm−2 and 8 nM, respectively. Moreover, the CeW nanosheets modified GCE exhibited excellent selectivity even in the presence of common metal ions and biologically co-interfering compounds. For the practical viability of the prepared amperometric sensor has been utilized in various water samples such as tap, lake and drinking water and the obtained recoveries are appreciable. [ABSTRACT FROM AUTHOR]

BiPO 4 nanomaterial was synthesized using EDTA (ethylene diamine tetra acetic acid) as the surfactant via a simple microwave method. The structure and morphology of BiPO 4 were systematically characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy (FE-SEM) studies. The obtained BiPO 4 nanoparticles were, on average, 150–300 nm. The electrochemical results showed that the specific capacitance of BiPO 4 obtained using the microwave route was up to 104 Fg −1 at a current density of 1 Ag −1 with a large potential window of 1.7 V. The material showed excellent cycling stability (92% capacitance retention) after 500 cycles at a current density of 1 Ag −1 . [ABSTRACT FROM AUTHOR]

Neutral tetradentate NO type complexes of Cu(II), Ni(II), Co(II) and Zn(II) have been synthesised using the Schiff base formed by the condensation of acetylacetone and p-anisidine. Microanalysis, molar conductance, magnetic susceptibility, IR, UV-Vis, H NMR, CV and EPR studies have been carried out to determine the structure of the complexes. From the data, it is found that all the complexes possess square-planar geometry. The EPR spectrum of the copper complex in DMSO at 300 K and 77 K was recorded and its salient features are reported. All the title complexes were screened for antimicrobial activity by the well diffusion technique using DMSO as solvent. The minimum inhibitory concentration (MIC) values were calculated at 37°C for a period of 24 h. It has been found that all the complexes are antimicrobially active and show higher activity than the free ligand. [ABSTRACT FROM AUTHOR]