XPS Studies Research Articles

Highly selective and effective copper removal from wastewater by magnetic precipitation separation

The presence of heavy metals in wastewater poses a substantial threat to both public health and the environment. However, the selective removal and separation of heavy metal ions at ultra-low concentrations from wastewater remains a considerable challenge. In this paper, we innovatively proposed a magnetic precipitation separation method to remove Cu (II) from wastewater using Fe3O4 nanoparticles and Na2S. In this process, the Cu (II) was reduced to CuS by Na2S, which then rapidly aggregated with Fe3O4 nanoparticles to form Fe3O4-CuS nanoclusters. SEM, DLS, XRD, VSM and XPS studies demonstrated that the removal of Cu (II) was related to the formation of Fe3O4-CuS nanoclusters. The results indicated that the removal efficiency of Cu (II) from wastewater could reach 99.75 % within 30 s. In contrast, the removal efficiencies of Co (II), Ni (II), and Zn (II) were 7.64 %, 6.14 %, and 8.41 %, respectively. In addition, the Fe3O4 nanoparticles were easily regenerated from Fe3O4-CuS nanoclusters using ultrasound, maintaining 98 % removal efficiency of Cu (II) after six consecutive cycles. These results suggested that this method held great potential for the removal of heavy metals from wastewater.

Highly efficient removal of adsorbed cationic dyes by dual-network chitosan-based hydrogel

This research presents the effective preparation of a novel dual network chitosan-based hydrogel (CMAPP) for the adsorption of methylene blue (MB), malachite green (MG), crystalline violet (CV), and basic fuchsin (BF) using the sol-gel method to address the escalating issue of dye pollution. FTIR, XRD, SEM, EDS, XPS, TGA, and zeta potential study examined hydrogel production and physicochemical properties. To ascertain the maximum adsorption capacity, the influences of pH, temperature, initial dye concentration, contact time, and adsorbent dosage on adsorption were systematically analyzed. It was observed that CMAPP demonstrated significant removal efficiencies (97.62%, 96.67%, 98.12%, and 99.32%) for the dyes MB, MG, CV, and BF at a concentration of 500 mg/L under optimal conditions. The findings from the adsorption kinetics and isotherm studies indicated that pseudo-second-order kinetics and the Langmuir model were the most appropriate for characterizing the adsorption process of hydrogels. The thermodynamic findings demonstrated that the adsorption process was exothermic and spontaneous. After five cycles of adsorption, the hydrogel demonstrated a consistent dye removal efficiency of around 80%, indicating commendable recyclability. In the interference studies, CMAPP exhibits superior anti-interference capability against CV and BF, which is advantageous for its practical application. The findings from XPS and FTIR investigations indicate that electrostatic attraction, hydrogen bonding, and n-π interactions are the primary forces between the adsorbent and the dyes. The synthesis of CMAPP offers an innovative approach for the effective elimination of cationic dyes and demonstrates significant potential in the treatment of complicated wastewater.

C2 Product Selectivity by 2D-Nanosheet of Layered Zn-doped Cu2(OH)3(NO3)- A Pre-Catalyst for Electrochemical CO2 Reduction.

The natural carbon cycle cannot mitigate and recycle the excess CO2 in the atmosphere, leading to a continuous rise in the global temperature. Electrochemical conversion of CO2 is one of the useful methods to utilise this anthropogenic CO2 and convert it into value-added chemicals. However, this process suffers the challenges of product selectivity and good Faradaic efficiency. In our current work, we report the role of Zn-doping in the 2D-Nanosheet of Cu2(OH)3(NO3)- a pre-catalyst that undergoes the in situ transformation into metallic state along with surface reconstruction. Our studies show, in the aqueous medium, the optimum amount of Zn plays a crucial role in the production of ethanol with the Faradaic efficiency of ∼45.2% though C-C coupling. Temperature-programmed desorption studies conclude that Zn increases the product selectivity for CO adsorption on Cu2(OH)3(NO3) nanosheets, further facilitating the C-C coupling at higher negative potential. The detailed XPS studies also reveal that the in-situ conversion of Cu2+ to Cu0 and Cu+ at negative potential contributes to the production of C2 products. The post-catalytic microstructural and spectroscopic studies converge to this point thatcumulative effect of oxidation state, surface reconstruction, as well as the presence of Zn modulates overall Faradaic efficiency for ethanol formation.

Improving visible light-driven CO2 conversion to high calorific fuels over sustainable highly crystalline and holey sulphur doped graphitic carbon nitrides

The effectiveness of CO2 reduction through g-C3N4 (CN) is considerably hindered by poor visible light absorption and the high rate of recombination of electron-hole (e−/h+) pairs. An effective method for increasing CO2 photoreduction efficiency is to incorporate non-metal components into the CN to modify its electronic properties and enhance its performance. This research presents the findings of our inquiry into sulfur-doped graphitic carbon nitrides (S–CN) for CO2 reduction through visible light. The XPS study reveals that the substitution of nitrogen atoms in the heptazine ring by sulfur (S) doping significantly influences the electronic configuration of CN, while the UV–visible absorbance spectra reveals that the CN band gap value 2.64 eV has reduced to 2.50 eV after S doping. Therefore, S–CN exhibits exceptional visible-light absorption, separation and migration of photoexcited e−/h+, corroborated by photoluminescence and transient photocurrent response experiments. Besides, S–CN demonstrated remarkable CO2 reduction capabilities without any cocatalyst or sacrificial agent, achieving CO/CH4 formation rates of 25/3 μmolg−1h−1, outperforming traditional CN. Our research highlights the relevance of impeding the e−/h+ recombination process to boost solar energy conversion output, suggesting potential for productive solar fuel generation using g-C3N4.

Room-temperature CO2 conversion to carbon using liquid metal alloy catalysts without external energy input

Conversion of CO2 to carbon using a catalyst typically requires significant energy input such as heat, pressure, or electricity. This is due to its strong bonds and the energy needed to initiate the reaction. The energy requirement for CO2 conversion may also lead to carbon emissions if sources are fossil-based. There is less exploration at low temperatures and without an external energy CO2 conversion to solid carbon. Here, we show a liquid metal alloy (In0.2Ga0.8) used as a catalyst for converting CO2 to carbon at room temperature without external energy. The carbon formed was characterized, and the calculated free energy of the reduction reaction was −530 kJ mol−1.The catalyst coated over a ceramic surface observed similar phenomena of CO2 conversion to carbon at room temperature. The conversion was five times higher at catalyst-coated ceramic membranes than at bulk catalysts. The CO2 conversion efficiency was 60 % at the catalytic membrane for continuous flow of CO2 at room temperature. EDX and XPS studies confirmed the formation of carbon at the catalyst surface. Our study may open the topic of membrane-based catalysis of CO2 for practical carbon conversion at lower operating costs at the industrial scale to achieve net-zero emissions.

Effective adsorption of Cr(VI) from aqueous solution by Mg-Fe LDH supported on orange peel activated carbon: isotherm, kinetic, thermodynamics and mechanism studies

The toxic Cr(VI) contaminating water released from the metallurgical, dyeing, and electroplating industries is getting worse day by day and is extremely hazardous to human health. Thus, the development of a cost-effective, quick, and efficient adsorbent is highly essential for the Cr(VI) decontamination from wastewater. Herein, a microwave-assisted carbon-based composite called Mg-Fe LDH@OPAC was prepared by assembling Mg-Fe LDH onto orange peel-activated carbon (OAPC). Prior to investigating deeply into the adsorption behavior of the composite, the Mg-Fe LDH@OPAC formation was confirmed by using instrumental techniques like FESEM, EDS, Zeta potential, XRD, FTIR, Raman, XPS, and BET analyzer. The material had a high surface area of 143.9 m2/g and showed a good monolayer Langmuir uptake capacity of 118.36 mg/g. Under ideal circumstances, the maximum amount of Cr(VI) was removed within just 120 min and showed high efficiency in the presence of other coexisting anions respectively. The adsorption was accounted by pseudo-second-order kinetics and spontaneous in nature. Ultimately, a possible adsorption mechanism was suggested, confirmed by XPS studies; which showed that oxidation-reduction, electrostatic interaction, and surface complexation reaction were responsible for Cr(VI) adsorption on Mg-Fe LDH@OPAC surface.

Nitrogen and Sulfur Doped Porous Carbon Sheet with Trace Amount of Iron as Efficient Polysulfide Conversion Catalyst for High Loading Lithium-Sulfur Batteries.

The major challenges in enhancing the cycle life of lithium-sulfur (Li-S) batteries are the polysulfide (PS) shuttling and sluggish reaction kinetics (S to Li2S, Li2S to S). To alleviate the above issues use of hetero atom doped carbon as cathode host matrix is a low-cost and efficient approach as it works as a dual-functional framework for PS anchoring as well as electrocatalyst for faster redox kinetics. Here, the dual role of the Fe-containing heteroatom-doped carbon sheets (CS) in chemisorption of Li2S6 and catalyzing its faster conversion to Li2S is established through UV-Vis, XPS and CV studies. To substantiate the catalytic effect composite cathodes were prepared by encapsulating sulfur in CS which is further blended with carbon nanotubes (CNTs) to form free-standing cathode. The electrochemical performance of the three cathodes viz., S@Fe-N-CS-CNT, S@Fe-S-CS-CNT and S@Fe-NS-CS-CNT were evaluated by constructing Li-S cells. Among all, the S@Fe-NS-CS-CNT delivers a high initial discharge capacity of 1017 mAh g-1 at 0.5 C rate and sustains 751 mAh g-1 capacity after 260 cycles with a capacity retention of 73.8 %. Even at high S-loading (12 mg cm-2), it delivers an initial discharge capacity of 892 mAh g-1 and it retained 575 mAh g-1 after 200 cycles.

Synthesis, characterization and application of MWCNT/TiO2 composite for photocatalytic reduction of benzophenone to benzopinacol

Photocatalytic reactions are widely investigated as a green chemistry approach towards organic molecule synthesis. Herein, we fabricated (MWCNT/TiO2) composite materials which are beneficial in the photocatalytic synthesis of benzopinacol on irradiation with UV–visible light. The precursor-layer-coating (PLC) method was successfully employed to produce a series of composite materials, X%-MWCNT/TiO2, where (X = 2, 4, 6, and 8 % w/w). The XRD confirmed major-anatase and minor-brookite TiO2 along with MWCNT in the composite. FE-SEM, HR-TEM, and EDAX revealed the expected composite microstructure, morphology, and compositional details. The nanosized (10 ̶30 nm), spherically shaped TiO2 particles were seen integrated to the MWCNT surface. The BET-surface area of the mesoporous composites enhanced from 83.77 to 114.39 m2/g as the MWCNT loading increased from 2 % to 8 %. The optical studies indicated a marginal shift in absorption edge towards longer wavelength with % MWCNT loadings. The band gap (Eg) was reduced and the charge pair recombination rate retarded. The PL, Raman and XPS studies supported the heterojunction formation at the interface. The photocatalytic activity was evaluated based on the % conversion efficiency of benzophenone to benzopinacol in the presence of light and composite as a photocatalyst. The 6 %-MWCNT/TiO2 demonstrated the highest photoactivity with an additional 34 % and 25 % yield in UV and sunlight respectively compared to bare TiO2. The effective light absorption, electronic excitation, charge pair separation and transfer mechanism at the MWCNT/TiO2 interface were responsible for enhanced photoactivity. The current investigation provided a promising strategy to produce hybrid photocatalytic material for organic molecule synthesis.

Optical absorption studies of pulsed-laser-engineered silver nanospheres and their enhanced catalytic performance in the degradation of toxic methylene blue dye

Pulsed laser ablation in liquid is an environment-friendly and one of the fastest physical routes to synthesize surfactant-free and stable metal/metal oxide nanoparticles with high purity and no harmful residues. In this study, we report the synthesis of silver nanospheres (AgNSs) using the nanosecond pulsed laser ablation in liquid (PLAL) technique resulting in the formation of a colloidal solution. Investigation of the optical properties using UV–Vis spectroscopy revealed the effects of laser wavelength, frequency, fluence, ablation time, and re-irradiation on the light absorption of the produced silver nanospheres. Physicochemical characterizations included FE-SEM, XRD, DLS, FTIR, and XPS techniques to evaluate the size, morphology, crystal structure, size distribution, zeta potential, and surface chemistry. FE-SEM studies revealed the formation of well-dispersed spherical Ag nanospheres with an average particle size of 209 nm without any agglomeration. DLS measurements showed high stability with a recorded zeta potential value of −38.27 (+/−1.81) mV and a wider size distribution. The XRD analysis indicated a face-centered cubic crystal structure with the formation of an oxide layer over the metallic silver core. The presence of silver and oxygen was confirmed through XPS studies with binding energies at 368.1 eV and 374.1 eV and oxide formation on the surface of Ag NSs. Finally, the catalytic activity of the Ag colloid was examined for the degradation of the toxic methylene blue dye. The results revealed an excellent catalytic response with 90 % of the dye degraded in just 15 min of reaction time. The kinetics of the degradation process were studied with a rate constant of 0.054/min−1 showcasing the effectiveness of the pulsed laser-synthesized silver colloidal nanomaterial as a sustainable approach for environmental remediation.

Surface engineering of carbon fiber using microwave micro arcing (MwMA) for enhanced performance of resulting PEEK composites

In this work microwave micro arcing (MwMA) has been utilized to engineer the surfaces of carbon fibers (CF) to enhance the interfacial bonding of resulting PEEK based composites. The CF were subjected to MwMA at different power levels ranging from 360 W to 900 W for 60 s to engineer their surfaces. The influence of MwMA on CF at various power levels was analyzed using SEM, contact angle measurement, AFM scans, and XPS study. Subsequently, MwMAed CF reinforced PEEK composite laminates were developed using compression molding. The MwMA on CF increased the surface wetting energy by 38% at 540 W microwave power level. XPS analysis suggested that MwMA at 540 W introduced oxygen containing functional group (C-O and C = O), which are likely responsible for increasing the adhesion between CF and PEEK polymer. The current study suggests that MwMA CF at 540 W showed an increment in tensile strength, flexural strength, interlaminar shear strength, and impact strength nearly by 22%, 61%, 28%, and 98% respectively. The MwMA method is novel method to improve the surface properties of carbon fibers and shows the potential use in structural applications.

Palladium immobilized on functionalized halloysite: A robust catalyst for ligand free Suzuki–Miyaura cross coupling and synthesis of pyrano[2,3-c]pyrazole motifs via four component cascade reaction and their in-silico antitubercular screening

This research introduces a novel organically functionalized halloysite-supported palladium catalyst, HMF-EDA-TMS@HAL-Pd(II) that was synthesized and thoroughly characterized using various analytical techniques like HR-TEM, FEG-SEM, EDX, XPS, FTIR, XRD, TGA, ICP-AES, EXAFS and DFT studies. The catalyst exhibited exceptional performance in Suzuki–Miyaura cross coupling reactions, demonstrating high efficiency and reusability up to seven cycles in aqueous ethanol medium. Motivated by its promising catalytic activity, we extended our investigation to explore its applicability in the synthesis of pyrano[2,3-c]pyrazole motifs via a four-component cascade reaction affording the desired products in good to excellent yields with broad substrate scope under green reaction conditions. In-silico antitubercular screening of pyrano[2,3-c]pyrazole motifs against DprE1 enzyme have shown promising results with inhibition constants ranging between 0.030 and 0.1 μM for compounds 5b, 5k and 5 l. This protocol has the advantages of wide substrate scope, high yield, excellent functional group tolerance, high efficiency and environmental benign procedure. These findings emphasized the catalyst's versatility and potential in diverse organic transformations, highlighting its importance in advancing sustainable synthetic methodologies.

Cerium-infused tungstate nanocrystals: Illuminating the future of solid-state lighting

Rare earth based luminescent materials have emerged as a focal point of the scientific investigation owing to their remarkable optical behaviour and potential applications. An effort has been made to develop a series of Ce3+ doped CaWO4 nano-phosphors using an ethylene-glycol assisted reflux route. The detailed structural and morphological properties have been examined through various analytical techniques. The +3-oxidation state of the activator ion Ce has been verified through the XPS study. The change in optical band gap due to the substitution is well discussed using diffuse reflectance spectroscopy. In Photoluminescence study, a broad emission centred at 465 nm is observed due to the 5D3/2→2FJ transitions (J = 7/2 and 5/2) and a significant enhancement in the emission peak is obtained for the optimized phosphor. Concentration quenching phenomenon, observed after 3 mol% of Ce3+ is mainly mediated by the electric multipole-multipole type interaction. The CIE diagram indicates the tuning of emission colour from blue to white region and the emission near white region for the optimized phosphor is further authenticated by its low colour purity value (43 %). The effective tunability of photo-physical properties and colorimetric parameters suggest the applicability of the optimized nano-phosphor in solid state lighting especially for outdoor illumination.

Photocatalytic performance of pristine NiO and Ni6MnO8 nanopowders in degradation of Rose Bengal dye.

Effective tuning of bandgap of transition metal oxides is a promising approach in improving their photocatalytic activity towards organic pollutant removal from water. The present paper describes synthesis of nickel oxide and Ni6MnO8 nanopowders by simple hydrothermal technique. During the synthesis of nickel oxide by hydrothermal process, addition of Mn source resulted in the formation of Ni6MnO8. X-ray diffraction analysis has confirmed the formation of nickel oxide and Ni6MnO8 both having cubic structures. The average crystallite size decreases from 20 to 12nm on increasing Mn source concentration during the synthesis of nickel oxide. Rectangular, hexagonal, and triangular faceted structures are revealed from the scanning electron microscopic images. HRTEM also indicated formation of cubical shaped structure with average sizes of 32 and 21nm for pristine NiO and Ni6MnO8 nanopowders. In the case of Ni6MnO8 nanopowder, inter-connected cubes are seen. Modification in Ni6MnO8 nanopowder is found to display multiple optical band gaps at 1.21, 1.82, and 2.65eV. The formation of Ni6MnO8 phase was further confirmed by XPS studies due to the presence of + 4 oxidation state of Mn. The photocatalytic properties of synthesized nickel oxide and Ni6MnO8 nanopowders are measured by using Rose Bengal dye under UV illumination. Enhancement in the photocatalytic activity is noticed in the case of Ni6MnO8 nanopowder as compared to nickel oxide nanopowder. Nearly 90% dye degradation is observed on utilizing Ni6MnO8 nanopowder.

Structural, optical, photocatalytic and thermal behaviour of (Nb, Ta) co-doped WO3 nanoparticles and its application in photocatalytic degradation of MG and RhB dyes

In this communication, eco-friendly, cost effective and facile hydrothermal route was adopted to synthesize pure WO3, Nb-doped WO3 and (Nb, Ta) co-doped WO3 nanoparticles. Phase, lattice constants, crystallite size and crystallinity have been evaluated through X-ray diffraction. The insertion of Nb and Ta ions into WO3 nanoparticles was confirmed by XPS, FTIR and EDS studies. HRTEM and SAED micrographs exhibited highly nanocrystalline nature of samples. UV–visible studies was carried out to analyse nature of band gap, band gap energy, extinction coefficient, refractive index, Urbach energy and optical conductivity of prepared samples. Optical band gap was narrowed from 2.94 to 2.49 eV and Urbach energy was extended from 0.08 to 0.35 eV through co-doping of (Nb, Ta) ions into WO3 NPs. Reduction in PL intensity revealed that electron-hole pair recombination rate was decreased with co-doping of (Nb, Ta) ions. The photo-degradation efficiency of (Nb 5 %, Ta 5 %) co-doped WO3 nanophotocatalysts was 93.12 % against MG and 90.11 % against RhB dyes. The rate constant was found to be increased from 0.0107 to 0.0203 min−1 for MG and 0.0086 to 0.0174 min−1 for RhB. Thermal results exhibited the weight loss in three phase degradation processes, and thermal stability. The results showed that (Nb 5 %, Ta 5 %) co-doped WO3 NPs is a potential candidate for practical applications in environmental remediation (organic dyes degradation).

Template synthesis of MgMn2O4 graded porous microspheres and electrochemical properties

Porous materials are more popular in electrochemical applications. In this study, MgMn2O4 microspheres with graded porous structure were prepared at lower temperature using a convenient template method, and MnCO3 microspheres were used as self-sacrificial templates. MgMn2O4 spinel microspheres were also prepared by template free method for comparison. The MgMn2O4 graded porous microspheres obtained by template method were assembled from nanoparticles with size of 20–50 nm, and have larger specific surface area (twice that of MgMn2O4 prepared by template free method). XPS studies show that both materials have mixed spinel structure with Mn present in multivalent states, and the material prepared by template method exhibits lower inversion degree. The electrochemical test results indicate that MgMn2O4 graded porous microspheres prepared by template method exhibit more excellent cycling and rate performance compared to materials prepared by template free method. The initial discharge capacity is up to 1429.5 mAh g−1 at a current density of 100 mA g−1, and discharge capacity remains 778.0 mAh g−1 after 150 cycles. Even at high rates (1000 mA g−1), it can stably output a cycling capacity of 295.5 mAh g−1. The MgMn2O4/LiCoO2 full cell delivers an initial discharge capacity of 83.4 mAh g−1 at a current of 100 mA g−1. The excellent electrochemical performance of MgMn2O4 microspheres prepared by template method may be related to their graded porous structure and low inversion degree. This study indicates that the electrochemical performance of MgMn2O4 materials can be greatly improved by adjusting the microstructural morphology.

In-situ synthesis of bifunctional N-doped CoFe₂O₄/rGO composites for enhanced electrocatalysis in hydrogen and oxygen evolution reactions

The development of cost-effective and efficient materials for electrochemical water splitting using non-noble metal oxide is a promising strategy to promote clean energy and mitigate environmental issues. In this study, we synthesized N-doped CoFe2O4 (NCF) and various wt% rGO-loaded N-doped CoFe2O4 (x = 1 %, 3 %, and 5 %; denoted as NCFRx) using a hydrothermal method. Subsequently, the NCF and NCFR3 samples were annealed at four different temperatures (y = 550, 600, 650, and 700 °C; denoted as NCFR3-y). FE-SEM, TEM, and XPS studies revealed a strong interface between rGO nanosheets and N-doped CF, acting as electron transport carriers that enhance performance in hydrogen and oxygen evolution reactions (HER and OER). The electrochemical evaluation of the prepared materials was carried out in a 1.0 M KOH electrolyte. The nickel foam (NF) electrode supported by the NCFR3–650 composite demonstrated excellent and stable electrocatalytic performance with a minimum overpotential of 73 mV and 170 mV at a current density of 10 mA/cm2 for HER and OER, respectively, and achieved excellent faradaic efficiencies of 91.01 % for OER and 90.48 % for HER. These results confirmed that the NCFR3–650@NF composite catalyst was comparable to standard Pt/C and IrO2, exhibiting lower overpotential and Tafel slope at a current density of 10 mA/cm2. The double layer capacitance (Cdl) of NCFR3–650@NF (7.70 mF/cm2) was higher than that of other electrocatalysts, indicating a large electrochemically active surface area. The structural properties of NCFR3–650@NF contributed to improved stability during long-term HER and OER analysis. Therefore, the developed NCFR3–650@NF electrocatalyst is a promising alternative to noble metal-centered systems for water splitting, offering overall high efficiency.

Mo-modified Pt/C electrocatalyst prepared by the catalytic decomposition of molybdenum peroxo-complexes for the hydrogen oxidation reaction with enhanced CO tolerance

Commercial 20 % Pt/C catalyst was modified by molybdenum via catalytic decomposition of peroxocomplexes of molybdenum with the subsequent reduction of the Pt2Mo1/C precursor in H2 flow at 600 °C. The detailed HRTEM, EDX, XRD and XPS studies showed that amorphous molybdenum oxide was deposited on Pt particles surface and partially on carbon support. After reduction of the Pt2Mo1/C precursor, the substantial Mo fraction merges the structure of Pt particles thus forming PtMo alloy with reduced lattice parameter, while the rest of molybdenum covers the surface of PtMo particles as MoO3. The presented method of Mo-modification of Pt-based catalysts provides rather simple way to vary Pt:Mo molar ratio. Electrochemical study revealed that the amount of the surface MoO3 plays a key role in the CO tolerance of the PtMo/C catalyst. As prepared Pt2Mo1/C precursor is 15 times superior to the Pt/C catalyst in the CO-tolerance. After reduction, the Pt2Mo1/C electrocatalyst exhibits extremely high CO-tolerance, more than 100 times higher than that of the pristine commercial platinum catalyst.

Analog‐Digital Hybridity of Resistive Switching in Ion‐Irradiated BiFeO3 Memristor for Synergistic Neuromorphic Functionality and Artificial Learning

AbstractMemristors‐based neuromorphic devices represent emerging computing architectures to perform complex tasks by outpacing the traditional Von‐Neumann architectures in terms of speed, and energy efficiency. In this work, the resistive switching (RS) behavior of sol‐gel grown and ion‐irradiated BFO films is investigated under electrical stimulus. The Ag/BFO/FTO memristors emulate a combination of digital and analog RS behavior within a single device. The possible mechanism of analog digital hybridity is addressed by considering the formation of the conducting filament by oxygen vacancies, Ag+ ions and Schottky barrier height modulation. The ion‐irradiated BFO samples are analyzed using the Raman, XRD, and XPS studies. To uphold bioinspired synaptic actions, crucial synaptic functionalities like pair‐pulse facilitation and long‐term potentiation/depression are effectively achieved. More intricate synaptic behaviors are also demonstrated such as spike‐time‐dependent plasticity and Pavlovian classical conditioning, which represent the prominent attributes of both learning and forgetting behavior. Additionally, high pattern recognition accuracy (96.1%) is achieved in an artificial neural network simulation by using the synaptic weights of the memristors. This synergistic effect of digital and analog RS in ion‐irradiated BFO can be beneficial for the emulation of complex learning behavior as well as its incorporation into low‐power neuromorphic computing.

Tuning the crystallinity of Cu-based electrocatalysts: Synthesis, structure, and activity towards the CO2 reduction reaction

The rising levels of CO2 have spurred growing concerns for our environment, and curbing CO2 emissions may not be practically viable with the expanding human population. One attractive strategy is the electrochemical CO2 reduction (CO2RR) into value added chemicals but because of the chemical inertness of the CO2 molecule, the electrochemical reduction requires a suitable catalyst. Cu-based catalysts have been largely investigated for CO2RR, however, the difficulty achieving a high selectivity and faradaic efficiency towards specific products, especially hydrocarbons, is still a challenge, alongside the concern over cost, stability and scarcity of the metal catalyst. The present research focuses on tuning the crystallinity of Cu nanoparticles via a green, cost-friendly, and facile method, called the urea glass route. Remarkably, the incorporation of a selected nitrogen-carbon rich source (namely, 4,5 dicyanoimidazole) at low temperatures allow the formation of an oxidized derived amorphous Cu system, whilst a second thermal treatment enables the transformation to crystalline Cu0. We found that the combination of surface Cu0 and Cu1+ (observed via XPS studies) present in our amorphous and crystalline Cu nanoparticles leads to interesting differences in the final catalytic activity when tested under CO2 reaction conditions. The combination of extended X-ray absorption fine structure (EXAFS) experiments and molecular dynamics simulations provides compelling evidence for the amorphous and metallic nature of Cu nanoparticles.

Preparation of magnetic chitosan/polyaniline nanocomposite for efficient remediation of nitrate and phosphate from water

A gel comprising of N-(2-hydroxyethyl)acrylamide (HEAAm), N,N’-methylenebis(acrylamide) (MBA), chitosan (CS), and polyaniline (PANI) made through microwave irradiation was evaluated for effective removal of nitrate and phosphate from water. The material was transformed into a nanocomposite by incorporation of magnetite (Fe3O4) nanoparticles. The nitrate and phosphate removal capacity of the nanocomposite was also evaluated in order to understand the effect of the presence of Fe3O4 on the adsorption efficiency of the gel. The nanocomposite exhibited enhanced adsorption capacity of 55.24 mg g−1 towards nitrate when compared to the value of 44.5 mg g−1 for the neat gel without nanoparticles. Also, the phosphate removal was enhanced from 51.4 to 60.60 mg g−1 due to the presence of Fe3O4 nanoparticles. The enhanced adsorption capacity of the nanocomposite is attributed to the increased surface area of the adsorbent (32.53 m2 g−1) arising from the contribution of the Fe3O4 nanoparticles embedded in the polymer matrix; as evidenced by surface area measurements. The superparamagnetic nature of the nanocomposite arising due to the presence of magnetite nanoparticles facilitates easy removal of the adsorbent after use during purification process. The mechanism of adsorption is confirmed to be the electrostatic interaction between the active sites on the nanocomposite and the adsorbate anions as indicated by XPS studies. The extent of adsorption and desorption as indicated by % desorption data and adsorption capacity values remained unchanged for about 5 cycles indicating the reusability potential of the material.