Biswajit Mondal

Two‐dimensional metal–organic framework (2D MOF) catalysts based on Co, Ni, Cu, and Zn were synthesized and evaluated for the oxygen evolution reaction (OER) and methanol oxidation reaction (MOR) in alkaline media. Linear sweep voltammetry (LSV) revealed contrasting catalytic trends: Co 2D exhibited the highest OER activity, whereas Ni 2D demonstrated superior MOR performance. At a current density of 10 mA cm ⁻² , Co 2D required an overpotential of 380 mV for OER compared to 410 mV for Ni 2D. In contrast, Ni 2D showed significantly enhanced activity toward MOR with favorable kinetics, as indicated by a low Tafel slope of 35 mV dec ⁻¹ . Electrochemical impedance spectroscopy revealed the lowest charge‐transfer resistance ( R _ct ) for Co 2D during OER and for Ni 2D during MOR, confirming the reaction‐specific catalytic behavior of these materials. Open‐circuit potential (OCP) measurements further indicated stronger methanol adsorption on Ni 2D within the inner Helmholtz layer. Chronopotentiometry coupled with ¹ H‐NMR product analysis demonstrated selective formate production with a Faradaic efficiency of 98.4% for Ni 2D, whereas Co 2D showed significantly lower efficiency. These findings highlight the intrinsic electronic differences between Ni and Co active sites that govern substrate oxidation and oxygen evolution, providing insights into the design of selective electrocatalysts for biomass‐derived alcohol oxidation and energy conversion reactions.

Ammonia (NH ₃ ) has emerged as a promising carbon‐free fuel and hydrogen carrier, offering a potential solution to meet growing global energy demands. In this study, we investigate the role of ligand electronic effects in a series of Mn–salen electrocatalysts for the ammonia oxidation reaction (AOR) in nonaqueous media. Our results reveal that electron‐withdrawing substituents promote an earlier onset potential and enhanced catalytic activity. A high‐valent nitrido‐manganese (V) salen species is identified as a key reaction intermediate through mass spectrometry during electrolysis, which undergoes nucleophilic attack by NH ₃ under oxidative conditions to produce nitrogen (N ₂ ). We also examined how solvent and electron‐transfer redox mediators affect the reaction. While the solvent shows no significant impact on catalytic performance, the use of a mediator markedly enhances reaction kinetics. Furthermore, the salen catalyst was evaluated for AOR in aqueous conditions, demonstrating an onset potential of 1.65 V versus RHE along with appreciable Faradaic efficiencies for N ₂ and H ₂ production of 93.6% ± 4.5% and 98.9% ± 1.7%, respectively, making it one of the few examples of selective AOR in aqueous medium.

The selective reduction of oxygen to water demands investigating interactions that govern both the rate and selectivity of the reaction. In this study, we examined the role of exogenous Lewis acid in the electrochemical oxygen reduction reaction (ORR) using Co‐Salophen and its derivatives as electrocatalysts. Acetic acid, (AA) served as an external Brønsted acid proton source, while calcium triflate, Ca(OTf) ₂ , functioned as the Lewis acid. Cyclic voltammetry (CV) and RRDE measurements revealed a positive shift in the onset potential and an increase in water selectivity upon addition of Ca(OTf) ₂ . This behavior could not be attributed to the electrostatic interactions between Ca ²⁺ and the catalyst solely, and the hydrolysis of Ca(OTf) ₂ to triflic acid. The observed increase in selectivity toward water and the earlier onset potential instead arises from enhanced acidity of AA in the presence of Ca(OTf) ₂ , supported by ¹ H‐NMR and a positive OCP shift from ‐0.95 to ‐0.82 V versus Fc ^+/0 . This increase in Brønsted acidity stems from a synergistic interaction between AA and a Lewis acid, resulting in better H ₂ O selectivity during ORR with Co‐Salophen catalysts.

Immobilization of transition metal in ionic framework structures for efficient oxygen evolution reaction.

Oxazolidine-based dinuclear Cu(II) complexes, [CuII2(μ2-Cl)2(Cl)2(L1R2S/1S2R)2] (1 and 2), were synthesized using a chiral N,N-donor ligand (L1R2S/1S2R) and CuCl2·2H2O. Single-crystal X-ray diffraction (SCXRD) confirmed the formation of a μ2-Cl-bridged copper complex. Structural features of the dinuclear complexes have been examined in detail, which provides information on C–H···π and π···π supramolecular interactions. The catalytic performance was evaluated in three complementary transformations: the oxygen evolution reaction (OER), catecholase activity, and phenoxazinone synthase (PHS) activity. Electrochemical investigations provide insights into water oxidation catalysis, while spectrophotometric studies were conducted to evaluate catecholase activity toward 3,5-di-tert-butylcatechol (DTBC), and for PHS, o-aminophenol (OAPH) was used. Faradaic efficiencies (FEs) were calculated as 86 ± 6% for O2 and 76 ± 3% for H2 in the case of OER activity, and catalytic efficiencies (kcat) were 1.9 ± 0.4 × 103 and 5.5 ± 0.6 × 103 h–1 for catecholase- and PHS-like activities, respectively. Electrochemical, kinetic, and mechanistic studies (in the case of biomimicking activities) reveal that the ligand environment facilitates the redox cycle of Cu(I)/Cu(II) and supports the substrate oxidation pathway. Dinuclear copper complexes resemble the active sites of copper oxidase enzymes, and the development of such systems is important for understanding biological activity and designing oxidation catalysts. These findings provide new insights into the design of multifunctional, earth-abundant catalysts capable of energy conversion and oxidation chemistry at the same time.

Mechanistic study of alcohol oxidation over a Co-doped Ni-based catalyst (aCo BDC/NF) revealed an HAT pathway for C–H bond breaking as the rate-limiting step. The catalyst is used for electrochemical PET upcycling.

Electro-activated Ni BDC/NF as a dual-purpose electrocatalyst for the valorization of lignocellulose-based small molecules and the upgradation of mixed plastic wastes into commercial chemicals along with concurrent H ₂ generation.

A covalently attached BQ/H ₂ Q mediator retards the ORR activity of Fe(Sal-H ₂ Q) as compared to its mediator-unattached analogue Fe(Sal).

This work explores the potential of an electrochemical mediator, Fcpy, for ammonia oxidation reaction to yield nitrogen (N₂) and hydrogen (H₂) with remarkable faradaic efficiencies in an undivided cell, validated through computational results.

The electrochemical conversion of carbon dioxide (CO₂) into valuable chemicals presents a promising avenue for achieving carbon neutrality. Nonetheless, this process faces significant challenges stemming from the slow kinetics of the anodic oxygen evolution reaction and the formation of low‐value O₂ as a byproduct. This study introduces a dual‐alkali electrolyzer that combines carbon dioxide reduction (CO₂RR) at the cathode with alkaline methanol oxidation (MOR) at the anode. Utilizing bismuth and nickel‐based metal–organic frameworks as catalysts for the cathode and anode, respectively, this dual‐electrosynthesis system achieves improved electron efficiency for formate production, demonstrating over 180% selectivity for both electrocatalytic CO₂ reduction reaction and MOR. Additionally, the hybrid MOR–CO₂RR system demonstrates impressive long‐term durability, maintaining operation for over 24 h. It provides a formate partial current density of 65 mA cm⁻² at a mere 2.4 V, significantly lowering energy consumption in comparison to traditional CO₂ electrolysis systems. This research emphasizes innovative strategies for enhancing electron utilization and minimizing energy consumption in CO₂ electrolysis while fostering the advancement of highly effective electrocatalysts.