Journals
2025 EN
Das Rupa · Kumari Prachi · Kumar Kundan
+6 more
Abstract Graphene quantum dots (GQDs) have caught significant attention in recent years due to their potential applications across various scientific disciplines. Heteroatom doping has emerged as a promising strategy to enhance the intrinsic properties of GQDs. Thus, the hunt for suitable dopants and low‐cost precursors for GQD synthesis is a future‐demanding topic. Herein, we report a simple and cost‐effective top–down approach synthesis method of nitrogen and sulfur co‐doped GQDs using semi‐bituminous coal and coke as precursors in which naturally present chemically bound sulfur and nitrogen also contribute to the dopant precursor. The synthesized nitrogen and sulfur co‐doped GQDs were characterized using various analytical techniques to examine their structural, morphological, and pH‐dependent photoluminescence properties. The synthesized CL‐NS‐GQDs exhibit a particle size of around 16–20 nm, having 3 to 4 layers of graphene confirmed by TEM and AFM analysis. We investigated the fluorescence behavior of N, S co‐doped GQDs across different pH levels (pH‐2, pH‐7, and pH‐10), and further enhanced the Photoluminescence properties by increasing the dopant concentration. Moreover, computational studies have also been conducted to examine the role of nitrogen and sulfur in GQD. Thus, this paper illustrates the fundamental understanding of utilizing low‐cost precursors to synthesize functional materials for diverse applications.
Journals
2025 EN
Murthy Gopi Narasimha · Sahu Uttam Kumar · Tripathy Swagatika
+2 more
ABSTRACT An efficient activated carbon was prepared from brinjal ( Solanum melongena L.) stalk through a thermal process and used for methylene blue (MB) dye removal using the Box‐Behnken design (BBD) model. The brinjal stalk activated carbon (BSAC) was analyzed by several instrumental techniques. The BSAC has a BET surface area of 90.09 m 2 /g with a high disordered external surface. XRD and FESEM data revealed that the BSAC is an amorphous structure with regular active pores. FTIR studies indicated the existence of active binding sites (–OH and –COOH) on the BSAC surface. The process parameters for MB dye removal were optimized in the BBD model by varying adsorbent dosage (0.1–1.0 g/L), pH (4–10), and contact time (10–120 min). About 93% of MB dye was eliminated in the optimal conditions of a dose of 0.81 g, 8.34 pH, and contact time of 117.29 min. The adsorption kinetics of MB dye onto BSAC followed a pseudo‐second‐order model ( R 2 = 0.997), indicating a chemisorption‐controlled mechanism. The Langmuir isotherm best described the equilibrium data ( R 2 = 0.96), suggesting monolayer adsorption with a maximum adsorption capacity of 161.79 mg/g. The adsorption process was driven by electrostatic attraction, π–π interaction, hydrogen bonding, and the pore‐filling process.
Journals
2025 EN
Yadav Rahul Kumar · Parveen Darakshan · Sahu Ritesh Kumar
+2 more
ABSTRACT We synthesized a series of 2‐aminotropone (N, O)‐based borane complexes ( 2a – 2c ) in a five‐membered scaffold that exhibits strong fluorescence in solution. The photoluminescence lifetimes of these complexes, measured in dichloromethane, range from 3.40 to 3.91 ns. Correspondingly, fluorescence quantum yields of boranes ( 2a ‐ 2c ) range from 10% to 15%, indicating the quantum yields and fluorescence decay times have minimal impact of the substituents present on the nitrogen atom. Treatment of these borane complexes with trimethylsilyl trifluoromethanesulfonate (TMS‐OTf) results in the formation of mixtures of borenium (three coordinated) and boronium (four coordinated) cations in solution. In contrast, reacting 2‐aminotropones with BBr 3 at room temperature selectively afforded boronium cations ( 4a – 4c ). All these neutral and cationic complexes were fully characterized using multinuclear NMR spectroscopy and single‐crystal x‐ray diffraction analysis. Furthermore, Density Functional Theory (DFT) studies were performed to analyze the electronic properties of both neutral and cationic boron species.
Journals
2025 EN
Sahu Bhanendra · Paul Sudipta · Jain Amul
+1 more
Abstract In this study, the development of a novel thermoresponsive UV‐shielding [poly(methyl acrylate) 100 ‐ block ‐poly( tert ‐butyl methacrylate) 50 ‐ block ‐poly(2‐(dimethylamino)ethyl methacrylate) 200 ]‐umbelliferone (PMA 100 ‐ b ‐PTBMA 50 ‐ b ‐PDMAEMA 200 ‐UMB) triblock copolymer with dual thermo and UV‐active functionality is reported for the fabrication of thermally switchable smart window and utilization as invisible fluorescent ink (suitable for security applications). The material demonstrates excellent thermal responsiveness, enabling reversible transparency modulation based on external temperature changes. This property makes it ideal for energy‐efficient smart window application by dynamically controlling light and heat transmission. Additionally, the polymer exhibits exceptional UV‐shielding performance, effectively blocking harmful UVA (320–400 nm) and UVB (280–320 nm) radiation while maintaining optimal optical clarity. Furthermore, its unique optical responsive, including invisibility under natural light and luminescence under UVA ( λ max = 352 nm) illumination, make it suitable for advanced information security applications. Detailed investigations of the photophysical properties of material reveal a precise coil‐to‐globule transition due to its thermoresponsive behavior, alongside robust UV‐blocking capabilities. This multifunctional material represents a significant step forward in the development of sustainable, high‐performance polymers for smart coatings, energy‐efficient technologies, thermo‐sensors, and secure information storage.
Journals
2025 EN
Banswar Durgesh · Rastogi Shobhit · Sahu Renu Raman
+7 more
Abstract Enhancing light‐matter interaction in nanostructures using metallic surface plasmons is a dependable route for improving efficiencies in optoelectronic applications. Plasmonic interfaces of organic cation‐based halide perovskites that show high quantum efficiency and enhanced carrier lifetimes are seen as a technologically important avenue for new‐age photovoltaics and quantum emitters. Here, several interesting multi‐particle interplays in hybrid structures of Ga nanodroplets and FAPbBr 3 crystals (Ga‐NCs) having novel practical applications are reported. In addition to the conventional emission enhancement, a dominant blueshift in the perovskite photoluminescence (PL) is seen in the presence of Ga nanoparticles, which are persistent down to low temperatures. The integrated PL intensity ratio has a non‐monotonic temperature dependence indicating a non‐trivial exciton‐phonon‐plasmon interplay. The time‐resolved photoluminescence measurements at different excitation wavelengths and transient absorption measurements reveal the strong influence of the Ga nanoparticles on the intrinsic phonon bottleneck typically observed in FAPbBr 3 crystals (NCs). Detailed calculations explain the observed results throwing light on the complex interplay of plasmons, excitons, and the phonons in these simple heterojunctions. Ga‐supported perovskite nanocrystals with higher quantum yield and ultrafast carrier relaxation pathways are seen to be an exciting system for quantum light emission with facile synthesis techniques.
Journals
2025 EN
Kumar Ashok · Chakkar Atul G. · Das Chayan
+4 more
Abstract Self‐powered broadband photodetectors utilizing 2D transition metal dichalcogenides (TMDs) are highly promising due to their remarkable light absorption capabilities and high sensitivity, making them suitable for applications such as military surveillance and wireless light detection systems. However, their performance is constrained by inadequate absorption, suboptimal charge carrier separation, and slow response times. In response to these limitations, the study fabricates a self‐powered photodetector employing a heterostructure composed of WS 2 nanoparticles anchored to CVD‐synthesized MoS 2 , operating within the visible to near‐infrared spectrum. The device demonstrates a responsivity of 283 mA W −1 and a detectivity 6.44 × 10 12 Jones, alongside an external quantum efficiency of 61% under exposure of 580 nm. In comparison to pristine MoS 2 , the MoS 2 ‐WS 2 photodetector exhibited approximately 12‐fold and 11‐fold enhancements in responsivity and detectivity, respectively, in addition to fast response time of ≈375 µs and 6 ms. Additionally, density functional theory (DFT) calculations are used to analyze the increase in dark current that is observed following WS₂ nanoparticle anchored on MoS₂. This investigation highlights the potential of 2D heterostructures in the development of high‐performance broadband photodetectors, which offer improved responsivity, stability, and self‐powered operation for advanced optoelectronic applications.
Journals
2025 EN
Chaudhary Yogesh · Sahu Ghrutanjali · Sankaran Kamatchi Jothiramalingam
+2 more
Abstract The fabrication of electrochemical sensing electrode with high sensitivity is vital for environmental monitoring of toxic contaminants in water and food sources. Here, a 3D hierarchical NiO@MXene derived TiO 2 /graphene (NMG) heterostructured electrode is developed using laser writing technique. The NMG heterostructured electrode is employed for voltammetric detection of both pesticide and heavy metals. For pesticide detection, NMG is employed to monitor paraquat (PQ) in 0.1 m phosphate buffer using stripping voltammetry, achieving a remarkable limit of detection of 0.0092 µ m under optimized conditions. Its practical applicability is demonstrated by successfully detecting PQ in real samples of aqueous coriander leaf extract. Interestingly, NMG exhibits high selectivity, repeatability, and reproducibility, highlighting its potential as a robust electrode for PQ detection. Furthermore, NMG facilitates individual and simultaneous detection of heavy metals, including Cd 2+ , Pb 2+ , Cu 2+ , and Hg 2+ with detection limits as 0.0036, 0.0018, 0.0043, and 0.0027 µ m , respectively, in the 0.1−2 µ m range using 0.1 m acetate buffer solution. The synergistic material combination with their complimentary physicochemical properties of NMG significantly enhance the electrochemical performance, making NMG as an effective electrode for sensitive and selective detection of PQ and heavy metals.
Journals
2025 EN
Mukherjee Swaraj · Ganaie Mubashir M. · Chatterjee Ayan
+4 more
Abstract HfO 2 is one of the most widely studied materials for resistive switching, owing to its CMOS compatibility and scalable performance. However, HfO 2 ‐based memristors suffer from stochastic filament formation, high device‐to‐device variability, and limited analog tunability due to abrupt and uncontrolled conductive filament growth, which limits their suitability for neuromorphic computing applications. Moreover, they often require external active electrodes like Ag or Cu to induce reliable switching, limiting material flexibility and integration. To overcome these challenges, AgHfO 3‐x is investigated, a silver‐containing perovskite that inherently supports uniform and stable analog switching without relying on active metal electrodes. Oxygen vacancies formed during deposition, together with lattice silver, create hybrid filaments that drive resistive switching. To enhance reliability, oxygen vacancies are suppressed by introducing additional oxygen during deposition, leading to more stable switching and an improved ON/OFF ratio. Beyond reliable memory behavior, the AgHfO 3‐x memristor demonstrates synaptic functionalities essential for neuromorphic computing. The device exhibits analog modulation of conductance in response to voltage pulse protocols, effectively emulating key biological learning processes such as potentiation, depression, and paired‐pulse facilitation. Furthermore, the device shows associative learning through a Pavlovian conditioning protocol, highlighting its potential as a hardware‐implemented artificial synapse in next‐generation brain‐inspired systems.
Journals
2025 EN
Sahu Bhanendra · Singh Nishikanta · Paul Sudipta
+1 more
Abstract The development of 4D‐printed soft active material (SAM) with programmable shape transformations and multifunctional properties remains a critical challenge for soft active materials. In this study, a 4D‐printed, dual‐responsive SAM is designed by integrating a 4‐arm star poly(N, N‐dimethyl acrylamide)‐ block ‐poly(dimethyl amino ethyl methacrylate)‐Br (4‐arm star (PDMA ‐b‐ PDMAEMA) 4 ‐Br) diblock copolymer with acrylic acid (AA), enabling precise shape morphing, tunable mechanical performance, and multi‐stimuli responsiveness. The SAM demonstrated excellent 3D printing, enabling the fabrication of complex 3D architectures with pre‐designed infill patterns. It exhibited high shape fixation and rapid shape recovery upon thermal activation at 44 °C. Moreover, its pH‐responsive swelling behavior facilitated selective dye removal, achieving ≈96% uptake of a model cationic dye at pH 10.5 and ≈65% uptake of a model anionic dye at pH 4.5. The SAM‐based robotic actuator successfully lifted weights, showcasing its potential for soft robotics applications. The integration of shape‐memory behavior with functional applications highlights the potential of this smart material in sustainable environmental technologies and advanced safety systems. These findings highlight the versatility of SAM for 4D‐printed adaptive systems, offering promising applications in biomedical engineering, and intelligent actuators.
Journals
2025 EN
Ghosh Madhusudan · Kadlag Sachin S. · Swain Kallola K.
+3 more
Abstract Thorium (Th), a naturally occurring radioactive element, poses long‐term health and environmental risks due to the radiotoxicity of its decay products and prolonged biological retention, necessitating its accurate detection in water systems. Existing fluorescence‐based sensors often suffer from poor water solubility, background emission, and matrix interferences, limiting their applicability in real aqueous environments. Herein, a novel turn‐on fluorescent sensor for Th 4+ in 100% aqueous media, based on a dicarboxylated tetraphenylethylene (TPE‐DCA) probe is reported. Th 4+ binding induces aggregation and results in a 180‐fold emission enhancement at 490 nm. The sensor operates optimally near neutral pH and achieves a detection limit of 11 n m (3 ppb), well below the WHO guideline for drinking water (245 ppb). It shows negligible interference from competing ions, including lanthanides and uranium, and performs robustly in tap, lake, and seawater samples. This work offers a simple, sensitive, and field‐relevant strategy for thorium monitoring in diverse environmental matrices.