Tejwant Singh Kang

3-Quinuclidinol-based surfactants comprising diverse self-assembled structures exhibit enhanced enzymatic activity and antimicrobial action.

Nanomaterials for efficient water remediation and electrochemical water splitting are of significant environmental importance, and their effectiveness can be further enhanced when they are prepared through sustainable synthesis strategies. At the same time, enhancing their photocatalytic efficiency is essential for practical applications. We report the biosurfactant-assisted in-situ decoration of few-layered 2D-MoS2 with Ag/AgBr nanoparticles (NPs) under sunlight irradiation in the presence of a large excess of Br‾ pre-adsorbed onto 2D-MoS2. The morphology of the nanocomposites (NCs) is controlled by a biosurfactant, choline deoxycholate ([Cho][Doc]), which also acts as a reducing agent, facilitating the in-situ photoreduction of excess Ag+ ions to Ag0 nano-grains originating from second to fifth unit cells of AgBr lattice. Br‾ ions pre-adsorbed onto MoS2 surface, trap the holes generated on the AgBr surface, and thus prevent charge recombination. This in conjunction with the formed heterojunctions between Ag0, AgBr, and MoS2-Br‾ phases, results in an exceptional performance for sunlight-driven degradation of Rhodamine B achieving nearly 100% of degradation within 5 min of irradiation and a rate constant of ~ 1.12 min-1. The observed rate constant is reportedly 21 times and 4 times higher than that reported for Ag@MoS2 and Ag/AgBr@MoS2 NCs, respectively. NCs also demonstrated excellent Electrochemical water splitting activity, delivering a low hydrogen evolution reaction potential of 65 mV and an oxygen evolution reaction overpotential of 340 mV at 10 mAcm-2. The NCs are quite stable for at least 15 hours for both HER and OER in 1M KOH. The present research is anticipated to emphasize the role of inorganic ions in the catalytic efficiency of nanomaterials, which would prompt exploration of new ways for designing valuable energy-harvesting nano-catalytic systems in a sustainable manner.

Micelles solvated in aqueous-DES milieu synergistically worked as sustainable electrolytes to foster enhanced charge storage kinetics via diffusive and electrical double-layer (capacitive) mechanisms, resulting in high-energy supercapacitors.

The need to develop novel and sustainable media without using conventional surfactants has driven the development of surfactant-free microemulsions (SFMEs). Deep eutectic solvents (DESs) and ionic liquids (ILs) are great alternatives to conventional organic solvents, using which SFMEs can be prepared. Herein, an SFME has been prepared using a DES based on the natural components L-arginine and lactic acid as the polar phase; 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonylimide), a hydrophobic ionic liquid (HIL), as the nonpolar phase; and ethanol as an amphiphile. The SFME has been duly characterized to establish its structural organization at the molecular level by employing various techniques such as conductivity measurements, dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), Fourier-transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. Investigations on the internal structure of the SFME reveal that ethanol does not form an effective barrier layer, instead, it forms hydrogen-bonded (H-bonded) solvent domains interacting mainly with DES nanoclusters, followed by the imidazolium cation at the HIL polar–nonpolar interface. The presence of such nanoinhomogeneity at the solvent interfaces imparts an associative nature to microemulsion droplets, which has never been reported before. The prepared SFME has been employed as a nanoreactor to explore the catalytic activity of cytochrome-c (Cyt-c). Variation in the phase composition of the SFME markedly affects the enzyme activity, wherein the DES-in-HIL phase of the SFME offers an optimal environment for ∼6.5 folds enhancement in enzyme activity as compared to that observed in buffer. The favorable cation-π and H-bonding interactions of arginine and lactic acid at the DES–ethanol interface, along with ethanol clusters, stabilize the structure of Cyt-c. This study provides new insights into the structural and functional aspects of SFMEs, which will encourage the development of new SFME systems for a broad spectrum of biocatalytic applications, along with the utilization of nanoinhomogeneity for constructing hierarchically self-assembled materials.

Introducing precise shape control in nanomaterial design while maintaining the catalytic applicability of the material and keeping the whole process a sustainable one is one of the many great challenges faced by material chemists. Herein, we report one-pot synthesis of highly efficient ternary mixed halide-based silver–silver chlorobromide (Ag@AgClxBr1–x) photocatalysts, prepared via anion exchange by a slow diffusion method in aqueous medium, followed by white light-induced symmetry breaking and in situ growth of the Ag phase onto the AgClxBr1–x lattice. The precise control on the morphology is driven by the templating effect of the mixed surfactant vesicles of two cationic surface-active agents, governed by metal–surfactant interactions at the interface of vesicular domains. The ternary mixed halide structure and controlled impregnation of plasmonic Ag nanoparticles render the material highly photocatalytically efficient in broad-spectrum sunlight-driven photo-oxidation of harmful organic dyes, Rhodamine B and Methyl Orange. The photocatalyst has shown complete degradation of the dye molecules within just 15 min of sunlight irradiation, exhibiting significantly higher catalytic rates (k = 0.64 min–1) than reported for the conventional Ag@AgX nanocomposites. The reduced number of reagents in an aqueous medium, along with the usage of more economical sources of light energy for the preparation and catalytic application of the anisotropic Ag@AgClxBr1–x nanoparticles in water remediation, makes the process sustainable. The present study is expected to pave the way for the development of more strategies to design anisotropic and shape-controlled ternary mixed silver halide-based nanomaterials for their unique physicochemical properties and high potency in photosensitive applications.

A new sustainable method for in‐situ preparation of graphene quantum dots (GQDs) from waste wheat straw at an optimal temperature (∼60°C) using a deep eutectic solvent (DES) composed of ZnCl ₂ and lactic acid is established. The Lewis acidic nature of ZnCl ₂ , along with Cl ⁻ ions, facilitated the breakdown and dissolution of wheat straw in DES. Various techniques confirm the formation of GQDs appended with different functional groups. The resulting GQDs showed excellent adsorption performance toward U(VI) ions, removing over 95% of U(VI) from groundwater samples (50–360 µg L ⁻¹ ) collected from the northwestern Punjab region, India, using batch and column methods. Adsorption studies indicated that the process is endothermic and spontaneous, and follows the Langmuir isotherm with a maximum adsorption capacity of 301 mg g ⁻¹ under optimum adsorption parameters: pH = 6, contact time = 30 min, and adsorbent dose = 0.4 g L ⁻¹ . The DES has been restored for reuse. This is the foremost report on dissolution and processing of wheat straw in a deep eutectic solvent (DES) under mild, low‐temperature conditions, enabling in‐situ formation of graphene quantum dots (GQDs) in a single step. This work is expected to enhance renewable biomass into sustainable materials using DESs.

Metal salt-based DES dissolves polyurethane with a remarkable 70% yield and promotes depolymerization under mild, sustainable conditions. The Lewis-acidic nature of ZnCl ₂ plays a key role in cleaving otherwise hard-to-break polyurethane bonds.

Ionic liquids (ILs) have proven to be a potential medium for the extraction and separation of essential oils (EOs) from the most varied sources. This review presents a summary of the primary outcomes obtained through the application of ionic liquid-based processes for the extraction and separation of different constituents of EOs (such as terpenes, ketones, phenols, oxides, esters, aldehydes, and alcohols). ILs have been examined as solvents, co-solvents, adjuvants, electrolytes, and cosurfactants, and they have been utilized in the synthesis of IL-supported materials for separation. In addition, the application of hybrid solvents, including deep eutectic solvents (DESs), further broadens the applicability of ILs to particular EO components. A key feature of ILs is their adaptable selectivity at the molecular level. Interactions such as hydrogen bonding, e.g., imidazolium-based ILs with hydroxyl groups of phenolic compounds, π–π stacking between aromatic cations and terpene backbones, and electrostatic or hydrophobic effects that control the solubilization and dissociation of esters and aldehydes enable ILs to achieve better resolution than conventional solvents. These interactions provide a higher extraction efficiency and better purity of the target compounds. Herein, IL-based solid–liquid green extraction techniques are reviewed and compared in terms of their extraction and separation capabilities. Modern trends, including computational methods, machine learning (ML) optimization, and advanced algorithms for process optimization techniques, are used to improve results, which are often used for single-parameter modifications, such as optimizing solvent ratios or extraction conditions. These examples show that ML can help improve IL-based extraction in practice, but complete end-to-end design systems are still in the future. Combining ML with multi-scale modeling and robotic testing for automated, iterative optimization is probably necessary to realize such dramatic potential. The environmental impact of ILs is also reviewed in terms of toxicity and biodegradability, along with reuse, recovery, and purification processes. The major achievements and future challenges in this discipline are addressed, with a specific focus on the primary loopholes encountered within the IL community devoted to the separation processes, and some measures are proposed to overcome the existing limitations.