02582nas a2200349   4500008004100000022001400041245016100055210006900216260000800285490000700293520135800300653003501658653002201693653003401715653002101749653002201770653001501792653002001807100001801827700002001845700001901865700002001884700002201904700002301926700001901949700004001968700002702008700002802035700001902063700002002082856013002102       2024                        eng d  a0935-964800aMorphology tuning via linker modulation: metal-free covalent organic nanostructures with exceptional chemical stability for electrocatalytic water splitting0 aMorphology tuning via linker modulation metalfree covalent organ  cMAR0 v363 a<p>
	The development of synthetic routes for the formation of robust porous organic polymers (POPs) with well-defined nanoscale morphology is fundamentally significant for their practical applications. The thermodynamic characteristics that arise from reversible covalent bonding impart intrinsic chemical instability in the polymers, thereby impeding their overall potential. Herein, a unique strategy is reported to overcome the stability issue by designing robust imidazole-linked POPs via tandem reversible/irreversible bond formation. Incorporating inherent rigidity into the secondary building units leads to robust microporous polymeric nanostructures with hollow-spherical morphologies. An in-depth analysis by extensive solid-state NMR (1D and 2D) study on H-1, C-13, and N-14 nuclei elucidates the bonding and reveals the high purity of the newly designed imidazole-based POPs. The nitrogen-rich polymeric nanostructures are further used as metal-free electrocatalysts for water splitting. In particular, the rigid POPs show excellent catalytic activity toward the oxygen evolution reaction (OER) with long-term durability. Among them, the most efficient OER electrocatalyst (TAT-TFBE) requires 314 mV of overpotential to drive 10 mA cm(-2) current density, demonstrating its superiority over state-of-the-art catalysts (RuO2 and IrO2).</p>
10abi-functional electrocatalysts10achemically robust10ahollow-spherical morphologies10aimidazole-linked10ainherent rigidity10ametal-free10awater splitting1 aKarak, Shayan1 aKoner, Kalipada1 aKarmakar, Arun1 aMohata, Shibani1 aNishiyama, Yusuke1 aDuong, Nghia, Tuan1 aThomas, Neethu1 aAjithkumar, Thalasseril, Govindanku1 aHossain, Munshi, Sahid1 aBandyopadhyay, Subhajit1 aKundu, Subrata1 aBanerjee, Rahul  uhttps://library.ncl.res.in/content/morphology-tuning-linker-modulation-metal-free-covalent-organic-nanostructures-exceptional02736nas a2200229   4500008004100000022001400041245010700055210006900162260000900231300001400240490000700254520195100261100002702212700001702239700001702256700001402273700002002287700001702307700002402324700002802348856013002376       2024                        eng d  a2050-748800aWater-chain mediated proton conductivity in mechanically flexible redox-active organic single crystals0 aWaterchain mediated proton conductivity in mechanically flexible  cMAR   a5866-58740 v123 a<p>
	Investigating electrochemical features of proton-conducting organic crystalline materials is relevant in developing efficient energy storage and conversion devices. However, the poor structural flexibility of the crystalline materials at the molecular level often impedes hydrogen bond reorganization of the proton carriers during proton migration, ultimately leading to low ionic conductivity. Here, we report crystals of azobenzene, functionalized with dipicolylamine at both ends (Azo-DPA), which contain an extended hydrogen-bonding network with water molecules in its structure. Interestingly, the crystals display remarkable mechanical flexibility explicitly probed by the nanoindentation technique. The mechanically flexible neutral organic crystals devoid of any acidic moieties (-COOH, -PO3H2, etc.) within the system, exhibit promising proton conductivity (1.63 x 10-4 S cm-1 at 30 degrees C under 95% relative humidity) which is almost 100 times better compared to the neutral organic systems reported to date. Mechanically flexible redox-active crystalline organic material (Azo-DPA) capable of impressive proton conduction was employed as an electrode material for the first time in an aqueous battery containing Zn2+ ions. The experimental and theoretical studies on the charge storage mechanism revealed the redox activity of the azo (-N 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 N-) centers involving reversible insertion/extraction of protons and Zn2+ ions. Ultimately, the electrode displayed a specific capacity similar to 49 mA h g-1 with almost 100% retention after 1400 cycles, encouraging the scope of redox-active organic crystalline materials for energy storage applications. Investigating the electrochemical features of proton-conducting flexible organic crystalline materials is crucial for the development of efficient energy storage and conversion devices.</p>
1 aHossain, Munshi, Sahid1 aGhosh, Meena1 aMondal, Amit1 aAjmal, P.1 aSaha, Monochura1 aReddy, Malla1 aKurungot, Sreekumar1 aBandyopadhyay, Subhajit  uhttps://library.ncl.res.in/content/water-chain-mediated-proton-conductivity-mechanically-flexible-redox-active-organic-single