@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 {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} } @article {48953, title = {Tailoring COFs: transforming nonconducting 2D layered COF into a conducting quasi-3D architecture via interlayer knitting with polypyrrole}, journal = {Journal of the American Chemical Society}, volume = {146}, year = {2023}, month = {DEC}, pages = {487-499}, type = {Journal Article}, abstract = {

Improving the electronic conductivity and the structural robustness of covalent organic frameworks (COFs) is paramount. Here, we covalently cross-link a 2D COF with polypyrrole (Ppy) chains to form a quasi-3D COF. The 3D COF shows well-defined reflections in the SAED patterns distinctly indexed to its modeled crystal structure. This knitting of 2D COF layers with conjugated polypyrrole units improves electronic conductivity from 10(-9) to 10(-2 )S m(-1). This conductivity boost is affirmed by the presence of density of states near the Fermi level in the 3D COF, and this elevates the COF{\textquoteright}s valence band maximum by 0.52 eV with respect to the parent 2D pyrrole-functionalized COF, which agrees well with the opto-electro band gaps. The extent of HOMO elevation suggests the predominant existence of a polaron state (radical cation), giving rise to a strong EPR signal, most likely sourced from the cross-linking polypyrrole chains. A supercapacitor devised with COF20-Ppy records a high areal capacitance of 377.6 mF cm(-2), higher than that of the COF loaded with noncovalently linked polypyrrole chains. Thus, the polypyrrole acts as a {\textquoteleft}{\textquoteleft}conjugation bridge{\textquoteright}{\textquoteright} across the layers, lowering the band gap and providing polarons and additional conduction pathways. This marks a far-reaching approach to converting many 2D COFs into highly ordered and conducting 3D ones.

}, keywords = {covalent organic frameworks, Electrical conductivity}, issn = {0002-7863}, doi = {10.1021/jacs.3c09937}, author = {Jain, Chitvan and Kushwaha, Rinku and Rase, Deepak and Shekhar, Pragalbh and Shelke, Ankita and Sonwani, Disha and Ajithkumar, Thalasseril G. and Vinod, Chathakudath Prabhakaran and Vaidhyanathan, Ramanathan} } @article {49192, title = {Resorcinol-Azodianiline Covalent Organic Framework Supported FeOOH Quantum Dot-Catalyzed Electrochemical Ammonia Synthesis under Ambient Conditions}, journal = {CHEMISTRY OF MATERIALS}, volume = {36}, year = {2024}, month = {AUG}, pages = {8229-8238}, type = {Journal Article}, keywords = {conversion, nitrogen, Recent Progress, reduction}, issn = {0897-4756}, doi = {10.1021/acs.chemmater.4c00859}, author = {Shekhar, Pragalbh and Kosugi, Kento and Singh, Himan Dev and Kushwaha, Rinku and Rase, Deepak and Matsuzaki, Takumi and Jain, Chitvan and Singh, Piyush and Singh, Yashraj and Vinod, Chathakudath Prabhakaran and Kondo, Mio and Masaoka, Shigeyuki and Vaidhyanathan, Ramanathan} }