@article {48070, title = {Covalent organic framework with electrodeposited copper nanoparticles - a desirable catalyst for the Ullmann coupling reaction}, journal = {Journal of Materials Chemistry A}, volume = {10}, year = {2022}, month = {JUL}, pages = {15647-15656}, type = {Article}, abstract = {

A covalent organic framework is a porous covalently-linked polymeric assembly built from molecular lego blocks, the monomers. A COF{\textquoteright}s high surface area, ordered pores, and intrinsic low density makes it a perfect heterogeneous catalyst component. Dispersing catalytic metal nanoparticles into the porous COF matrix in a {\textquoteleft}capping-agent-free{\textquoteright} manner can aid the maximal utilization of the active sites. To generate single-site catalysts, metals have been anchored to dense supports, or metal ions have been coordinated to the porous organic framework. The latter has superior atom efficiency and a substrate diffusion advantage. Stably nestling neutral metallic clusters into open-framework supports with no specifically strong binding groups requires a different approach. If infused from extremely dilute electrolytes, metal clusters can be nanoconfined into electrically activated COFs. At low-loadings, it can resemble a single-site catalyst with high atom efficiency. Herein, we report the larger scale synthesis of IISERP-COF15 and electrochemical loading of copper nanoparticles into its pores at loadings as low as 3.34 wt\%. We employed classical Ullmann reactions to adjudge its activity. Typical turnover numbers for the catalysts reported in the literature are approximately 50-100. A Cu@COF shows high activity with a very low catalyst loading of 0.25 mol\% (TON around similar to 300-350 vs. 4 for neat CuCl2 center dot 2H(2)O (homogeneous catalyst) and turnover frequency (similar to 15-17 h(-1))). We recycled it for up to 3 cycles. Furthermore, we report a multi-fold Ullmann reaction producing an unreported hexaaldehyde to demonstrate the latitude of the catalyst. Our work points to the potential of a dilutely loaded metal@COF as a mimic of the single-site catalyst for synthesizing valuable C-O linked molecules. Our findings from computational modeling shed light on the role of the COF as an active nanoporous support for Ullmann C-O coupling.

}, issn = {2050-7488}, doi = {10.1039/d2ta01326f}, author = {Chandran, Chandana and Singh, Himan Dev and Leo, Liya S. and Shekhar, Pragalbh and Rase, Deepak and Chakraborty, Debanjan and Vinod, Chathakudath P. and Vaidhyanathan, Ramanathan} } @article {48132, title = {Incorporating conducting polypyrrole into a polyimide COF for carbon-free ultra-high energy supercapacitor}, journal = {Advanced Energy Materials}, volume = {12}, year = {2022}, month = {SEP}, pages = {2200754}, type = {Article}, abstract = {

Redox-active covalent organic frameworks (COFs) store charges but possess inadequate electronic conductivity. Their capacitive action works by storing H+ ions in an acidic electrolyte and is typically confined to a small voltage window (0-1 V). Increasing this window means higher energy and power density, but this risks COF stability. Advantageously, COF{\textquoteright}s large pores allow the storage of polarizable bulky ions under a wider voltage thus reaching higher energy density. Here, a COF-electrode-electrolyte system operating at a high voltage regime without any conducting carbon or redox active oxides is presented. Conducting polypyrrole (Ppy) chains are synthesized within a polyimide COF to gain electronic conductivity (approximate to 10 000-fold). A carbon-free quasi-solid-state capacitor assembled using this composite showcases high pseudo-capacitance (358 mF cm(-2)@1 mA cm(-2)) in an aqueous gel electrolyte. The synergy among the redox-active polyimide COF, polypyrrole and organic electrolytes allows a wide-voltage window (0-2.5 V) leading to high energy (145 mu Wh cm(-2)) and power densities (4509 mu W cm(-2)). Amalgamating the polyimide-COF and the polypyrrole as one material minimizes the charge and mass transport resistances. Computation and experiments reveal that even a partial translation of the modules/monomers intrinsic electronics to the COF imparts excellent electrochemical activity. The findings unveil COF-confined polymers as carbon-free energy storage materials.

}, keywords = {carbon free capacitors, cation-anion co-storage, conductivity, high energy capacitors, polypyrrole doped COFs}, issn = {1614-6832}, doi = {10.1002/aenm.202200754}, author = {Haldar, Sattwick and Rase, Deepak and Shekhar, Pragalbh and Jain, Chitvan and Vinod, Chathakudath Prabhakaran and Zhang, En and Shupletsov, Leonid and Kaskel, Stefan and Vaidhyanathan, Ramanathan} } @article {48448, title = {Hydroxide ion-conducting viologen-bakelite organic frameworks for flexible solid-state zinc-air battery applications}, journal = {Nanoscale Horizons}, volume = {8}, year = {2023}, month = {JAN }, pages = {224-234}, type = {Article}, abstract = {

Adaptable polymer-based solid-state electrolytes can be a game-changer toward safe, lightweight flexible batteries. We present a robust Bakelite-type organic polymer covalently decked with viologen, triazine, and phenolic moieties. Its flexible structure with cationic viologen centers incorporates counter-balancing free hydroxide ions into the polymeric framework. By design, the aromatic groups and heteroatoms in the framework can be activated under an applied potential to prompt a push-pull drive, setting off the towing of hydroxide ions via weak electrostatic, van der Waals, and hydrogen-bond interactions. The frontier orbitals from a DFT-modeled structure certify this. The hydroxyl-polymer requires minimal KOH wetting to maintain a humid environment for Grotthuss-type transport. The hydroxide ion conductivity reaches a value of 1.4 x 10(-2) S cm(-1) at 80 degrees C and 95\% RH, which is retained for over 15 h. We enhanced its practical utility by coating it as a thin solid-state separator-cum-electrolyte on readily available filter paper. The composite exhibits a conductivity of 4.5 x 10(-3) S cm(-1) at 80 degrees C and 95\% RH. A zinc-air battery (ZAB) constructed using this polymer-coated paper as electrolyte yields a maximum power density of 115 mW cm(-2) and high specific capacitance of 435 mA h g(-1). The power density recorded for our ZAB is among the best reported for polymer electrolyte-based batteries. Subsequently, the flexible battery fabricated with IISERP-POF11_OH@FilterPaper exhibits an OCV of 1.44 V, and three batteries in series power a demo traffic signal. To underscore the efficiency of hydroxide ion transport through the complex multifunctional backbone of the polymer, we calculated the diffusion coefficient for OH- (Exp: 2.9 x 10(-5) cm(2) s(-1); Comp. 5.2 x 10(-6) cm(2) s(-1)) using electrochemical methods and MD simulations. Climbing-edge NEB calculations reveal a large energy barrier of 2.11 eV for Zn2+ to penetrate the polymer and identify hydroxide ions within the polymer, suggesting no undesirable Zn2+ crossover. Our findings assert the readily accessible C-C-linked cationic polymer{\textquoteright}s capacity as a solid-state electrolyte for ZABs and any anion-conducting membrane.

}, issn = {2055-6756}, doi = {10.1039/d2nh00455k}, author = {Rase, Deepak and Illathvalappil, Rajith and Singh, Himan Dev and Shekhar, Pragalbh and Leo, Liya S. and Chakraborty, Debanjan and Haldar, Sattwick and Shelke, Ankita and Ajithkumar, Thalasseril G. and Vaidhyanathan, Ramanathan} } @article {48735, title = {Made to measure squaramide COF cathode for zinc dual-ion battery with enriched storage via redox electrolyte}, journal = {Advanced Energy Materials}, volume = {13}, year = {2023}, month = {SEP}, type = {Article}, abstract = {

Aqueous rechargeable batteries are promising grid-scale energy storage devices because of their affordability, operational safety, and environmental benignity. Among these, Zn-ion batteries (ZIBs) have unfolded new horizons. Designing superior cathodes for ZIBs is crucial. Covalent organic frameworks (COFs) can be made redox active with a high storage surface. Here, for the first time, a chelating COF with redox-active ZnI2 in a ZnSO4(aq) electrolyte is combined. Including iodide harvests an approximately threefold enhancement in capacity from 208 to 690 mAh g(-1) at 1.5 A g(-1), the highest among all the COF-derived ZIBs. Remarkably, a charge-discharge curve at 1.3 V exhibits very limited dropout voltage and super-flat platform, with a remarkable capacity of 600 mAh g(-1) at 5 A g(-1) stable up to 6000 cycles, confirming that the polyiodide generation and storage are sustainable. The COF{\textquoteright}s dual-ion storage (Zn2+ and polyidode) delivers a ZIB with the highest energy density. Spectro-electrochemical measurements coupled with X-ray photoelectron spectroscopy unambiguously unveil the existence of multiple polyiodide species, with I-3(-) and IO3- ions as the prominent species. The latter gets reduced at the COF electrode under an applied potential, leaving I-3(-) as the major species stored on the COF. The prospect of COF-polyiodide((aq)) is a windfall for metal-ion batteries.

}, keywords = {covalent organic frameworks, flexible batteries, polyiodide, redox electrolytes, Zn ion batteries}, issn = {1614-6832}, doi = {10.1002/aenm.202301049}, author = {Kushwaha, Rinku and Jain, Chitvan and Shekhar, Pragalbh and Rase, Deepak and Illathvalappil, Rajith and Mekan, Deep and Camellus, Augastus and Vinod, Chathakudath Prabhakaran and Vaidhyanathan, Ramanathan} }