Browsing by Author "Mudit Dixit"

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Nitrogen- and Sulfur-Enriched Conjugated Polymer Network as an Electrocatalyst for the Oxygen Reduction Reaction and as a Cathode Material for Zinc–Air Batteries
(American Chemical Society, 2025) Arpita Maurya; Neelam Gupta; Priti Singh; Nitika Bhutani; Anamika; Rik Rani Koner; Mudit Dixit; Biplab Kumar Kuila
Over the past decade, heteroatom-doped metal-free carbon materials (MFCMs) have been recognized as effective oxygen reduction reaction (ORR) catalysts. However, the active centers for the ORR in MFCMs are difficult to precisely confirm and controllably synthesize using conventional methods such as high-temperature pyrolysis or heteroatom doping. To elucidate the active center precisely and the structure–property relationship, we demonstrated a conjugated polymer network (CPN), TTB, comprising triazine, thiophene, and benzothiadiazole for ORR and as a cathode catalyst for a zinc–air battery. Density functional theory calculations revealed that the benzothiadiazole building block acts as an active center, leading to ORR catalytic activity. TTB was thoroughly characterized through different characterization techniques like FTIR, XPS, XRD, FESEM, HRTEM, and BET surface area and pore size analysis. The onset potential of 0.81 V vs reversible hydrogen electrode (RHE), diffusion-limiting current density of 3.0 mA/cm2, and E1/2of 0.68 V vs RHE with good electrochemical stability are comparable to the benchmark ORR catalyst (10% Pt/C). TTB was further used as the cathode electrocatalyst for a zinc–air battery, resulting in an open-circuit potential of 1.46 V and a specific capacity of 613 mAh g–1. A rechargeable zinc–air battery was also fabricated with TTB and RuO2as the cathode electrocatalysts, showing a voltage gap of 0.9 V and good cyclic stability. These findings show that the rational design and precise synthesis of conjugated polymer networks can facilitate the development of new ORR catalysts useful as cathode materials for zinc–air batteries. © 2025 American Chemical Society
Selective binding of benzoquinone with a PtII-cyclophane constructed on the skeleton of N,N′-bis(salicylidene)-p-phenylenediamine: Synthesis and spectroscopic studies
(Scientific Publishers, 2009) Niraj Kumari; Rishikesh Prajapati; Mudit Dixit; Lallan Mishra
The Schiff base N,N′-bis(salicylidene)-p-phenylenediamine has been complexed with Pt(en)Cl2 and the resulting PtII- cyclophane, [Pt(en)L]2·4PF6, reacted with phenol, resorcinol, hydroquinone or benzoquinone in DMSO solution. Their binding has been monitored by the variation in the corresponding UV-visible and emission spectral patterns. The binding properties are compared with the earlier reported ZnII-cyclophane [Zn(bpy)L]2 (bpy = 2,2'-bipyridine). A few solid adducts of phenol and benzoquinone with the PtII-cyclophane complex and hydroquinone as well as that of resorcinol with the Zn-cyclophane have also been synthesized and characterized.
Side-Chain Modification in Conjugated Polymer Frameworks for the Electrocatalytic Oxygen Evolution Reaction
(American Chemical Society, 2023) Neelam Gupta; Sayan Halder; Ravi Prakash Behere; Priti Singh; Sayan Kanungo; Mudit Dixit; Chanchal Chakraborty; Biplab Kumar Kuila
Conjugated polymer frameworks (CPFs) have recently sparked tremendous research interest due to their broad potentials in various frontline application areas such as photocatalysis, sensing, gas storage, energy storage, etc. These framework materials, without sidechains or functional groups on their backbone, are generally insoluble in common organic solvents and less solution processable for further device applications. There are few reports on metal-free electrocatalysis, especially oxygen evolution reaction (OER) using CPF. Herein, we have developed two triazine-based donor-acceptor conjugated polymer frameworks by coupling a 3-substituted thiophene (donor) unit with a triazine ring (acceptor) through a phenyl ring spacer. Two different sidechains, alkyl and oligoethylene glycol, were rationally introduced into the 3-position of thiophene in the polymer framework to investigate the effect of side-chain functionality on the electrocatalytic property. Both the CPFs demonstrated superior electrocatalytic OER activity and long-term durability. The electrocatalytic performance of CPF2, which achieved a current density of 10 mA/cm2 at an overpotential (η) of 328 mV, is much superior to CPF1, which reached the same current density at an overpotential of 488 mV. The porous and interconnected nanostructure of the conjugated organic building blocks, which allowed for fast charge and mass transport processes, could be attributed to the higher electrocatalytic activity of both CPFs. However, the superior activity of CPF2 compared to CPF1 may be due to the presence of a more polar oxygen-containing ethylene glycol side chain, which enhances the surface hydrophilicity, promotes better ion/charge and mass transfer, and increases the accessibility of the active sites toward adsorption through lower π-π stacking compared to hexyl side chain present in CPF1. The DFT study also supports the plausible better performance toward OER for CPF2. This study confirms the promising potentiality of metal-free CPF electrocatalysts for OER and further sidechain modification to improve their electrocatalytic property. © 2023 American Chemical Society.