Mahuya Bandyopadhyay

The synthesis of efficient electrocatalysts for the oxygen evolution reaction (OER) in water splitting remains challenging due to slow reaction kinetics. In the present investigations, a novel octanuclear nickel(II) double cubane molecular cluster, [Ni ^II ₄ (LH ₃ ) ₃ ( µ ₃ ‐OH)( η ¹ ‐H ₂ O) ₂ ] ₂ ·2NO ₃ ·2H ₂ O·CH ₃ OH ( 3 ), has been synthesized using a Schiff‐base ligand LH ₄ (2‐[2‐hydroxy‐3‐(hydroxymethyl)‐5‐methylbenzylideneamino]‐2‐methylpropane1,3‐diol). Complex 3 was immobilized on activated carbon cloth (CC), referred to as CC‐3 , and investigated as an electrocatalyst for the OER in an alkaline medium. Single‐crystal X‐ray diffraction revealed that complex 3 comprised two distorted cubane‐like [Ni ₄ ( µ ₃ ‐OR) ₃ ( µ ₃ ‐OH)] ⁺ cores interconnected by flexible pendant ─CH ₂ OH groups from the ligand. Electrochemical analysis showed that CC‐3 exhibited excellent OER activity in 1.0 m KOH, which was reflected in a low overpotential of 290 mV at 10 mA cm ^{− 2} with a Tafel slope of 48 mV dec ⁻¹ . The catalyst showed remarkable stability, undergoing negligible degradation after 2000 CV cycles and 20 h of chronoamperometric measurement. Mechanistic studies suggest the formation of catalytically active high‐valent Ni ³⁺ ─OH intermediates during the OER. Fe ³ ⁺ addition to the electrolyte enhanced OER activity, attributed to high‐valent reactive species stabilization. This work demonstrates polynuclear nickel complexes as effective molecular electrocatalysts for OER, providing insights into their catalytic mechanisms.

This research entailed the synthesis and functionalization of mesoporous materials with sulfonic acid groups, subsequently embedding a binuclear Zn complex into the porous matrices. The modified was comprehensively analyzed utilizing several techniques like XRD, NMR, BET, UV, TEM, XPS, etc. The outcomes validate the successful integration of the essential functional groups and Zn complex, as well as the preservation of phase purity, crystalline structure, and morphology. The material showed remarkable photodegradation efficiency when exposed to visible light. Methylene blue, crystal violet, and malachite green exhibited 99% degradation within 15, 10, and 5 min, respectively, illustrating their potential to address environmental challenges associated with organic dye pollution. Moreover, a substantial 91% degradation of rhodamine B transpires within a 30‐min period. This modified material performs exceptionally well in challenging settings, including elevated pH and salinity, showcasing their versatility and resilience across diverse environmental contexts. Additionally, a machine learning pipeline was developed to predict the dye deterioration rate under varying input conditions. Through feature engineering, data preprocessing, and hyperparameter tuning, optimized boosting regressors were utilized for prediction. Performance metrics and feature importance scores revealed that adsorption dosage exerts the greatest influence on the predicted dye deterioration rate. The novelty lies in developing a modified material demonstrating ultrarapid photodegradation of diverse organic dyes under visible light, coupled with exceptional resilience in harsh environmental conditions.

Silicoaluminophosphates (SAPOs) are structurally diverse materials widely used in separation, catalysis, and environmental applications. In this study, a simple post‐synthetic method is used to create a hybrid porous material by immobilizing a copper(II) complex onto base‐functionalized SAPO molecular sieves. The copper complex, synthesized using 2,9‐dimethyl‐1,10‐phenanthroline and copper nitrate, is structurally confirmed through single‐crystal X‐ray diffraction. The effective activity in ring‐opening reaction of epoxide is achieved when this complex is anchored on amine‐functionalized SAPO materials. Characterization techniques such as powder X‐ray diffraction, N₂ adsorption‐desorption, Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscope, and thermogravimetric analysis confirm the structural integrity, surface properties, and thermal stability of the materials. High conversion efficiencies of 90% and 88% are achieved using copper‐complex‐immobilized SAPO‐34 and SAPO‐5, respectively. To enhance industrial applicability, machine learning techniques are applied to predict product conversion and selectivity. Methods such as linear regression, support vector machine (SVM), and k‐nearest neighbors (kNN) are evaluated, with SVM and kNN showing strong predictive performance. Error metrics like mean‐squared error, mean absolute percentage error, and R score validate the model accuracy. This work highlights the effective integration of functionalized SAPOs with ML tools for catalytic optimization and industrial‐scale applications.

The oxygen evolution reaction (OER) is integral to electrochemical energy systems; however, its intrinsic sluggish kinetics necessitate the design of high‐performance electrocatalysts to minimize overpotential, enhance the durability, and optimize the efficiency. Significant efforts have been dedicated to developing OER catalysts based on earth‐abundant transition‐metal complexes. Here, the efficacy of a tetranuclear cubane‐cored Ni(II) complex, [Ni₄(LH)₄(MeOH)]·CHCl₃ (1), in OER is demonstrated. The complex is synthesized using a tetradentate Schiff‐base ligand, [2‐{(E)‐(2‐hydroxyphenylimino)methyl)‐6‐(hydroxymethyl)‐4‐methylphenol}], and characterized by single‐crystal X‐ray diffraction. The redox properties of complex 1 are evaluated by cyclic voltammetry in the solid state, which emphasize the quasireversible oxidation state of the Ni(II) metal center. The complex 1 is immobilized on activated carbon cloth (CC), referred as CC‐1, which demonstrates efficient OER catalysis, subsequently activating to form the Ni(O)OH catalyst. The postreaction analysis including UV–vis, FTIR, scanning electron microscopy–energy‐dispersive X‐ray spectroscopy, and X‐ray photoelectron spectroscopy confirm the stability of molecular complex 1. The results demonstrate efficient OER catalysis with a low overpotential of 330 mV versus reversible hydrogen electrode and a Tafel slope of 64 mV dec⁻¹, confirming an effective OER catalyst in alkaline medium with a deep understanding of the core reaction mechanisms.

In this study, mesoporous materials (MCM-41 and MCM-48) were synthesized and functionalized with an acid group through a post-synthetic modification method. A mononuclear Zn complex [Zn(dmp)Cl₂] (dmp = neocuprine) was also prepared and incorporated into a functionalized mesoporous material. Extensive characterization of the material married was carried out using techniques such as X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), and Fourier-transform infrared spectroscopy (FT-IR) to evaluate the characteristics of modified materials. The characterization results revealed that the post-synthetic modification did not alter the phase purity, crystallinity, or morphology of the mesoporous materials while confirming the successful grafting of the desired sulphonic acid functionality and Zn complex. The Zn complex-grafted-functionalized mesoporous materials were then assessed for their photo-degradation using methylene blue (MB) and rhodamine B (RB). The results demonstrated exceptional photo-degradation efficiency of the modified materials under sunlight. Within 15 min, 10 mg/ml of dye concentration, and adsorbent dosage 0.15 mg/ml and 0.1 mg/ml, degradation efficiencies of 99% and 92%, were achieved for MB using M-48-S-Zn₁ and M-41-S-Zn₁, respectively. Similarly, 91% and 78% degradation rates were achieved within 30 min for RB using the same materials. The modified mesoporous materials exhibited a remarkable degradation performance even in challenging environments, including highly acidic, basic, and salt-concentrated conditions. This highlights the versatility and robustness of the modified materials in different environmental scenarios.

Economic synthesis of amine-modified solid adsorbents is pivotal for the global-scale direct air capture (DAC) technologies required to realize net-zero emissions. To address the problems of the traditional reflux method using excessively costly amino silane, we propose introducing silane by impregnation into mesoporous silica with interconnected three-dimensional pores. X-ray diffraction, Fourier transform infrared spectroscopy, N₂ adsorption-desorption, transmission electron and scanning electron microscopies, magic-angle spinning nuclear magnetic resonance, and elemental analysis identified the spatial distribution of amino silane in the materials with different loading levels. The results of structure characterization and a comparison with a reference experiment (using a porous support with one-dimensional pores and/or the conventional reflux method) revealed that the proposed strategy provided a uniform amine distribution, together with a high utilization efficiency of the amino silane. We also demonstrate that the obtained material has a high adsorption capacity and good recycling stability comparable to those of the previously reported amino silane modified adsorbents under simulated DAC conditions.