Department of Chemistry

Designing of efficient electrode material for the enhancement of energy density with extended cycle life for supercapacitors is a crucial factor. Transition metal oxides (TMOs) and Mixed TMOs are such nanomaterials which has been explored extensively due to its cost-effective and earthly abundance. But the low specific capacitance with electrochemical and structural instabilities obstructs TMOs from its practical application. To address this challenge, a low-cost nanocomposite with a delafossite-type (CuCrO2(CCO)) and perovskite-type (CuZrO3(CZO)) crystal structure has been developed which displayed an enhanced electrochemical activity and prolonged cycle life for charge storage applications. This nanocomposite demonstrated remarkable charge storage capability, delivering maximum capacity value of 179.5 C/g (373.12 F/g) in 2 M potassium hydroxide (KOH) at 0.5 A/g, and sustaining cycle life of 5000 GCD runs at 5 A/g. Furthermore, we constructed a hybrid supercapacitor (HSC) device that revealed high power and energy density of 600 W/kg and 24 Wh/kg at 1 A/g, and preserved 80 % of its capacitance with a minimal loss in coulombic efficiency. Additionally, to ascertaining the potential sustainability in energy storage applications, we have integrated them with a commercially available photovoltaic (PV) module and demonstrated the device's capability to power a standard light emitting diode (LED).

Plastic-aggregates are made up from unused or waste plastic and natural aggregates which have recently been emerged as a significant addition to the existing emerging contaminants list mainly in the coastal environment. The transformation from plastics/microplastics to Plastic-aggregates signifies a crucial shift in our understanding and use of plastics and prompting us to reconsider their fundamental characteristics along with possible environmental threats. When plastic waste is incinerated for the purpose of disposal, it combines with organic and inorganic substances present in the surrounding environment, leading to a new type of material. Besides, some natural factors (physical, chemical, biological or in combination) also act upon discarded plastics to combine with rocks and other earthen materials to form plastic-aggregates. Our research aims to build fundamental knowledge and critically review the possible formation process, classification, and possible degradation of all such polymer-rock compounds along with their impact on the ecosystem. The knowledge gap related to the degradation and release of secondary pollutants from these agglomerates is to be addressed urgently in future research. Development and standardization of proper sampling and reporting procedures for plastic-aggregates can enhance our understanding related to their impacts on human health as well as to the entire environment as these aggregates contain different toxic chemicals.

The authors regret the oversight in one of the author's (Manjunatha Thondamal) affiliation details occurred during the final proof reading. The affiliation detail for the author-Manjunatha Thondamal is: d Department of Biotechnology, School of Technology, Gandhi Institute of Technology and Management (GITAM), Visakhapatnam, Andhra Pradesh, 530045, India. The authors would like to apologise for any inconvenience caused.

Gold nanoclusters (Au NCs) have found wide range of applications in environmental, chemical and health sectors as sensors, catalytic agents and theranostic molecules, respectively, due to their ultrasmall size and excellent optical properties. However, a comprehensive battery of bioassays of Au NCs were lacking on a well-established biological model system, which would enhance its potential to be used as an optical probe with application in theranostics. The current investigation aims to address the in vivo compatibility of Au NCs to improve their design, evaluate their biological impact, and validate their potential for bioimaging applications. We have used the Caenorhabditis elegans as a model organism in our present study due to their short life cycle facilitating evaluation of drug effects in reasonable time frame and transparent body framework suitable for in vivo imaging. These features facilitate accurate information regarding the uptake and biodistribution of Au NCs inside the tissues and body parts. Additionally, different nanotoxicological studies such as biodistribution of NCs and its subsequent impact on the health span, brood size, pharyngeal pumping and tail thrashing of C. elegans were observed as a measure of the Au NCs biocompatibility. Our results strongly demonstrate that the human serum albumin (HSA)-bound Au NCs are non-toxic, biocompatible and do not exhibit any adverse effect on the physiology and survival of the C. elegans. This study, employing a comprehensive battery of bioassays, is the first to systematically evaluate the long-term biocompatibility and non-toxicity of Au NCs across the entire lifespan of an organism, measured through multiple physiological parameters. These findings underscore the potential of Au NCs as safe and effective diagnostic and therapeutic agents for medical and clinical applications.

This article reports facile fabrication of a multifunctional smart surface having superhydrophobic self-cleaning property, superoleophilicity, and antimicrobial property. These smart surfaces have been synthesized using the stereolithography (SLA) method of the additive manufacturing technique. SLA is a fast additive manufacturing technique used to create complex parts with intricate geometries. A wide variety of materials and high-resolution techniques can be utilized to create functional parts such as superhydrophobic surfaces. Various materials have been studied to improve the functionality of 3D printing. However, the fabrication of such materials is not easy, as it is quite expensive. In this work, we used a commercially available SLA printer and its photopolymer resin to create various micropatterned surfaces. Additionally, we applied a low surface energy coating with ZnO nanoparticles and tetraethyl orthosilicate to create hierarchical roughness. The wettability studies of created superhydrophobic surfaces were evaluated by means of static contact angle using the sessile drop method and rolling angle measurements. The effects of various factors, including different concentrations of coating mixture, drying temperatures, patterns (pyramids, pillars, and eggbeater structures), and pillar spacing, were studied in relation to contact angles. Subsequently, all the functional properties (i.e., self-cleaning, oleophilicity, and antibacterial properties) of the as-obtained surfaces were demonstrated using data, images, and supporting videos. This inexpensive and scalable process can be easily replicated with an SLA 3D printer and photopolymer resin for many applications such as self-cleaning, oil-water separation, channel-less microfluidics, antibacterial coating, etc.

Microplastics and nanoplastics are almost everywhere in biological and environmental systems, posing serious risks to human health and ecology. However, due to their complex matrices, varied sizes, and morphologies, their detection and quantification remain challenging. Particularly, Raman and surface-enhanced Raman spectroscopy (SERS) hold great promise for the detection, characterization, and quantification of micro/nanoplastics. In this review, we introduce the Raman and SERS fundamental principles, instrumentation, and SERS substrate design strategies. Particularly, emphasis is placed on SERS-enabled ultrasensitive detection, integration with chemometrics and machine learning tools, culminating in the real-world applicability. Additionally, we elaborate on the current limitations, including signal variability, lack of standardization, and sample preparation challenges. Finally, future directions involving artificial intelligence (AI) integration, substrate engineering, and multi-modal analytical approaches are discussed.

Two tungsten-based oxides, Li2WO4 and h-WO3, were investigated as anode materials for lithium-ion batteries in half-cell configuration (vs. Li) within the voltage window of 3.0–0.05 V. The initial lithiation process in both materials involves Li intercalation into the lattice, followed by a conversion reaction. The Li2WO4 anode exhibited outstanding electrochemical performance, delivering a high reversible capacity of 547 mAh g−1 at 0.1C and 355 mAh g−1 at 1C after 70 cycles. Furthermore, it demonstrated fast charging capability and exceptional cycling stability, maintaining a discharge capacity of 280 mAh g−1 at 5C even after 1500 cycles. In comparison, the h-WO3 anode displayed significantly lower performance under similar conditions. These results highlight that the presence of pre-existing lithium ions in the host lattice of Li2WO4 facilitates efficient lithiation and delithiation, contributing to its superior capacity and extended cycle life. This study underscores the potential of Li2WO4 as a promising anode material for next-generation lithium-ion batteries.

LiFePO4 (LFP) is widely used as cathode material in Li-ion batteries in electric vehicles (EV’s). The theoretical capacity of LFP is 170 mAhg−1. It is difficult to achieve the theoretical capacity value, especially at high C-rates, mainly because of its poor ionic as well as electronic conductivity. Several doping strategies have been adopted of which Mn as well as V doping individually, show beneficial effect in improving the electrochemical performance. However, co-doping of these two ions and the synergistic effect, if any, on the electrochemical performance of LFP has not been explored hitherto. In the present study, Mn and V co-doped LFP cathode materials were synthesized by solvothermal method. Phase formation was confirmed by X-ray diffraction studies, while 7Li MAS NMR spectra revealed changes in isomeric shift (-18.03 ppm for pristine LFP, -1.01 ppm for Mn-doped, and -0.65 ppm for Mn, V co-doped LFP), confirming Mn and V are incorporated into the olivine lattice. The co-doped LFP exhibited a unique two-dimensional morphology with uniform, fluffy particles (~ 3 µm × 2 µm). X-ray photoelectron spectra confirmed the presence of Fe2+, Mn2+, and V4+ oxidation states. The Li-ion diffusion coefficient (DLi+) of Mn and V co-doped LFP (6.93 × 10−15 cm2s−1) was higher than that of pristine LFP (2.97 × 10−15 cm2s−1), indicating enhanced Li-ion diffusion in the co-doped sample. Electrochemical tests in half-cell mode showed that co-doped LFP achieved a 167, 153 and 145 mAhg−1 capacity at 0.1, 1.0, and 2.0 C-rates, respectively. Inaddition, the co-doped composition showed excellent capacity retention, even at high C-rates i.e., 135 mAhg−1 with 90% retention after 500 cycles at 1C and 101.3 mAhg-1 with 70% retention after 1000 cycles at 2C. Also, the co-doped phase exhibited lower polarization and charge transfer resistance, highlighting its potential for high-performance lithium-ion batteries.

In this study, disk-shaped copper sulfide nanoparticles (CuS-NPs) were synthesized via a simple co-precipitation method and used as a photocatalyst for the reduction of carbonate species derived from marble dust into acetic acid (AcOH). The photocatalytic reaction was carried out under monochromatic light (525 nm) in a hydrogen peroxide-water mixture using CuS-NPs. Key parameters such as solvent composition, light source, catalyst concentration and reaction time were optimized to get the maximum yield of AcOH. The reaction mechanism was investigated using radical scavenging experiments. The practical applicability of the approach was further tested on two additional real-life carbonate waste materials, i.e., chalk dust and carbonate scale.

We synthesized biodegradable and economically viable solid-state electrolyte films based on konjac glucomannan (KG) and sodium iodide (NaI). Among the KGNaI-x (x = 31-69 wt%) films, KGNaI-69 exhibits superior flexibility, biodegradability, and sodium superionic conductivity of 77.9 mS cm-1. The KGNaI-69-based supercapacitor delivers outstanding electrochemical efficiency and cycling stability, retaining 84.4% capacitance after 5000 cycles establishing its potentiality toward flexible energy storage devices.

Conventional liquid electrolytes utilized in supercapacitors suffer from leakage, flammability, and poor adaptability making them unsuitable to design flexible, wearable, and portable devices. Despite the significant advancements in designing flexible electrode materials towards the fabrication of safer and integrated energy storage systems, the development of optically transparent and mechanically flexible polysaccharide-based solid-state electrolytes remains comparatively limited. Herein, we report a series of flexible solid-state electrolyte (FSSENaI-x; where x = 27, 43, 53, 60, 65, and 69 wt%) films, composed of konjac glucomannan (KGM), hydroxypropyl methylcellulose (HPMC), and sodium iodide (NaI). Among them, the FSSENaI-65 film exhibits optimal properties in terms of mechanical, optical, and ionic conductivity suitable for designing supercapacitor devices. It achieves a Young's modulus of ∼2.5 MPa with an exceptional elongation at break at 118%, along with an optical transparency of 88% at 800 nm. It delivers a high ionic conductivity of 2.77 mS cm−1 at room temperature and a wide electrochemical stability window of 2.4 V. A solid-state supercapacitor assembled with the FSSENaI-65 film shows a specific capacitance of 159 F g−1 at 1 A g−1, with an excellent cycling stability retaining 87.5% of its specific capacitance over 4000 cycles at 5 A g−1. It maintains a stable performance under bending conditions with a capacitance retention of 72.2% over 2000 cycles at 5 A g−1. The device furnishes a high energy density of 22.1 Wh kg−1 and power density of 500.6 W kg−1 at 1 A g−1 confirming its potential for next-generation flexible energy storage systems.

Metal–organic framework (MOF) glasses combine the structural tunability of crystalline MOFs with the processability of amorphous materials, offering exciting opportunities for functional hybrid materials. Here, a one-pot, solvent-free synthesis is reported of an Fe2+-based MOF glass, gFe-tBubipy, with the composition [Fe2(im)3.12(bim)0.88(tBubipy)0.11]·[Fe(Cp)2]0.09 (im− = imidazolate, bim− = benzimidazolate, tBubipy = 4,4′-di-tert-butyl-2,2′-bipyridine, Cp− = cyclopentadienyl anion). This material forms a continuous random network structure of four-connected tetrahedral and octahedral Fe2+ nodes and exhibits an exceptionally low glass transition temperature (Tg = 87 °C). Despite its amorphous nature and complex composition, gFe-tBubipy exhibits a high degree of local structural order that enables strong antiferromagnetic exchange interactions between Fe2+ centers. Remarkably, it exhibits clear signatures of spin-glass behavior, with a well-defined magnetic freezing transition ≈14 K. This combination of a MOF glass exhibiting a distinct glass transition with spin-glass magnetism arising from topological disorder and frustrated, short-range magnetic interactions represent a significant advance. This discovery underscores the transformative potential of MOF glasses as a versatile platform for exploring the interplay between structural disorder and cooperative magnetic phenomena in hybrid materials.

An upper rim tetra-imidazolyl-phenanthroline derivatized calix[4]arene conjugate (L) was synthesized and characterized using different analytical, spectral, microscopic and diffraction techniques. The incubation of L with CuSO4·5H2O in PBS buffer (20 mM) for 1 h resulted in the formation of a nanoflower material. The L-coated copper phosphate nanoflowers (L@CuPNFs) were characterized through Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction, and microscopy techniques. The peroxidase mimetic activity of L@CuPNFs was assessed, and the results were compared with those of unmodified CuPNFs as a control. The peroxidase activity was demonstrated using three different substrates, viz., tetramethylbenzidine (TMB), ortho-phenylenediamine (OPD) and guaiacol. The progress of the oxidation reaction of the model substrates in the presence of L@CuPNFs and H2O2 was demonstrated through absorption spectra measured as a function of time. The changes could be qualitatively gauged from the observed visual colour variation. The oxidized species were identified by measuring the ESI-MS spectrum of the reaction mixture. The rate of oxidation of these substrates in the presence of H2O2 was higher when L@CuPNFs were used as a catalyst, and this was much greater than the reaction rate observed with the unmodified CuPNF, which was not coated with L. All these results confirmed that the coating of L enhanced the peroxidase mimetic activity of the nanoflowers.

Organofluorine compounds are widely used but pose environmental concerns. We report a base-mediated didefluorination of o-trifluoromethyl benzylamines via difluoroquinone methide intermediates, yielding monofluorinated tricyclic 2H-imidazoles. This efficient method showcases a broad substrate scope and offers mechanistic insight through a 1,4-elimination pathway of two fluoride ions.

We have developed a transition metal-free defluorinative method for 2-(trifluoromethyl)phenol, which facilitates the synthesis of chromones. This reaction features a previously unexplored [4 + 2] annulation of in situ-generated reactive difluoro quinone methide and 1,3-dicarbonyl compounds. Notably, this distinct mode of reactivity applies to a diverse array of substrates and operates under mild conditions, showcasing scalability.

The development of high-performance, fully non-fused ring electron acceptors (NFREAs) for organic solar cells (OSCs) is often hindered by multistep synthesis, use of hazardous reagents, and high synthetic complexity (SC), ultimately limiting their figure-of-merit (FOM). In this study, we report three simple and cost-effective NFREAs, SN-1, SN-2, and SN-3, featuring a dialkoxybenzene central core and hexyldicyanorhodanine terminal acceptor groups linked via distinct π-bridging units: furan, thiophene, and ethylenedioxythiophene (EDOT), respectively. These NFREAs were synthesized in just four steps using a direct C–H arylation reaction, without any hazardous reagents, with very high overall yields of up to 49%. To enhance the molecular planarity and charge transport, an intramolecular noncovalent interaction strategy was employed to restrict the C–C bond rotation between the π-conjugated units. Notably, SN-3 exhibited multiple O···S and O···H interactions between core and end groups, effectively rigidifying the backbone and promoting J-aggregation. As a result, PM-6:SN-3-based OSCs achieved a power conversion efficiency (PCE) of 11.56%, a high FOM of 67.09, and a low SC value of 17.26. In comparison, devices based on SN-1 and SN-2 delivered PCEs of 10.26% and 6.97%, respectively. These findings underscore the critical role of noncovalent interactions in conformationally stabilizing simple NFREAs and highlight their potential for high FOM OSCs.

The metal doping process not only enhances the intrinsic properties of semiconducting perovskite nanocrystals (PNCs), including optoelectronic, magnetic, and electrochemical properties, but also significantly improves their photophysical performance. For instance, Mn doping can enhance the photophysical properties of CsPbCl3PNCs to some extent. In addition to doping, surface passivation is a promising strategy to further improve the photophysical properties and stability of these materials. In this study, we demonstrate that the surface defect states of the Mn-doped CsPbCl3PNCs can be effectively reduced through postsynthesis surface passivation with mucic acid at room temperature, resulting in enhanced photophysical properties and stability. The XRD patterns confirmed the successful doping of Mn into the CsPbCl3lattice. FTIR and XPS measurements verified the successful mucic acid passivation. Notably, the mucic acid-treated Mn–CsPbCl3PNCs exhibited a photoluminescence quantum yield of 55–57%, compared to just 18% for unpassivated Mn–CsPbCl3. The photostability test confirms that passivated PNCs are more stable than those without passivation. The Mn-CPC-MA-3 PNCs showed significantly improved current stability and intensity under visible light illumination with a higher photocurrent density of ∼0.01 μA/cm2versus −0.029 μA/cm2for Mn-CPC PNCs.

Metal doping offers a potent strategy for enhancing the optical properties and stability of CsPbCl3 (CPC) perovskites. While Mn doping has drawn attention to its unique attributes, it has failed to achieve the benchmarks set by CsPbBr3 and CsPbI3. To bridge this gap, a codoping approach involving earth-abundant and cost-effective FeCl2 has been explored in this study. PL emission peak intensity increased after codoping with various FeCl2 concentrations in Mn-doped CPC (Mn-CPC) nanocrystals. Fe2+ effectively enhances the Mn doping efficiency in CPC across 0.1-0.3 mmol concentrations by replacing some Pb2+ sites. The resultant Fe-codoped Mn-CPC nanocrystals display orange emission in hexane at 594-606 nm, boasting photoluminescence quantum yields up to 22-27%. Notably, codoped nanocrystals exhibit better photostability under ambient conditions and UV-light irradiation than Mn-CPC. The improved photoresponse characteristics induced by Fe2+ codoping highlight the potential of these nanocrystals for integration into UV-visible photodetectors and other optoelectronic devices. The electrochemical property of Fe ion-codoped Mn-CPC PNCs showed better photocurrent density results than Mn-CPC.

Molecular photoswitches that absorb sunlight and store it in the form of chemical energy are attractive for applications in molecular solar thermal energy storage (MOST) systems. Typically, these systems utilize the absorbed energy to photoisomerize into a metastable form, which acts as an energy reservoir. Diarylethenes featuring aromatic ethene π-linkers have garnered research interest in recent years as a promising class of T-type photoswitches, which undergo photocyclization from an aromatic ring-open form into a less aromatic or non-aromatic ring-closed form. Based on several recent computational and experimental studies, this perspective analyzes the potential of these switches for MOST applications. Specifically, we discuss how they can be made to simultaneously achieve high energy-storage densities, long energy-storage times, and high photocyclization quantum yields by tuning the aromatic character of the ethene π-linker.

Organic solar cells (OSCs) have achieved remarkable progress, with power conversion efficiencies (PCEs) surpassing 19-20%, driven by the development of polymeric electron donors and non-fullerene acceptors (NFAs) in bulk-heterojunction (BHJ) architectures. BHJ OSCs, which rely on physical blending of donor (D) and acceptor (A) materials, face significant challenges in maintaining long-term stability. This instability limits the commercial viability of BHJ OSCs despite advancements in optimizing their morphology and device architecture. Single-component organic solar cells (SCOSCs) have emerged as a promising alternative to address these stability challenges. By covalently linking D and A units into a single molecule these single-material devices combine the advantages of light absorption and charge transport within a unified structure, eliminating complex interfacial layers and mitigating phase-separation issues inherent in BHJ systems. To date, SCOSCs have reached a maximum power conversion efficiency (PCE) of 15%, marking notable progress toward bridging the performance gap with BHJ devices. This review highlights the structural advancements in SCOSCs, with a particular emphasis on molecular dyads, D-A double cable polymers and conjugated block copolymers, and their photovoltaic performance. Furthermore, it discusses potential strategies for future innovations to improve the efficiency and scalability of SCOSCs.