01769nas a2200205 4500008004100000022001400041245011600055210006900171260006500240300000800305490000700313520097500320653002301295653002001318653000901338653001501347100003701362700003601399856012801435 2016 eng d a1420-304900aGold incorporated mesoporous silica thin film model surface as a robust SERS and catalytically active substrate0 aGold incorporated mesoporous silica thin film model surface as a aST ALBAN-ANLAGE 66, CH-4052 BASEL, SWITZERLANDbMDPI AGcMAY a6670 v213 a

Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement. The applicability of these thin films as catalysts as well as a robust SERS active substrate for model catalysis study is tested. Compared to bare silica film our gold incorporated silica, GSM-23F gave an enhancement factor of 10(3) for RhB with a laser source 633 nm. The reduction reaction of p-nitrophenol with sodium borohydride from our thin films shows a decrease in peak intensity corresponding to -NO2 group as time proceeds, confirming the catalytic activity. Such model surfaces can potentially bridge the material gap between a real catalytic system and surface science studies.

10agold nanoparticles10amodel catalysis10aSERS10aThin films1 aSekhar, Anandakumari, Chandrasek1 aVinod, Chathakudath, Prabhakara uhttp://library.ncl.res.in/content/gold-incorporated-mesoporous-silica-thin-film-model-surface-robust-sers-and-catalytically02283nas a2200265 4500008004100000022001400041245012300055210006900178260000900247300001400256490000700270520141500277653000901692653001801701653001001719653001901729653001601748653001301764100002001777700001801797700003601815700001901851700002501870856012201895 2019 eng d a1944-824400aDirect Z-scheme g-C3N4/FeWO4 nanocomposite for enhanced and selective photocatalytic CO2 reduction under visible light0 aDirect Zscheme gC3N4FeWO4 nanocomposite for enhanced and selecti cFEB  a6174-61830 v113 a

Photocatalytic reduction of CO2 to renewable solar fuels is considered to be a promising strategy to simultaneously solve both global warming and energy crises. However, development of a superior photocatalytic system with high product selectivity for CO2 reduction under solar light is the prime requisite. Herein, a series of nature-inspired Z-scheme g C3N4/FeWO4 composites are prepared for higher performance and selective CO2 reduction to CO as solar fuel under solar light. The novel direct Z-scheme coupling of the visible light-active FeWO4 nanoparticles with C3N4 nanosheets is seen to exhibit excellent performance for CO production with a rate of 6 mu mol/g/h at an ambient temperature, almost 6 times higher compared to pristine C3N4 and 15 times higher than pristine FeWO4. More importantly, selectivity for CO is 100% over other carbon products from CO, reduction and more than 90% over. H-2 products from water splitting. Our results clearly demonstrate that the staggered band structure between FeWO4 and C3N4 reflecting the nature-inspired Z-scheme system not only favors superior spatial separation of the electron hole pair in g-C3N4/FeWO4 but also shows good reusability. The present work provides unprecedented insights for constructing the direct Z-scheme by mimicking the nature for high performance and selective photocatalytic CO2 reduction into solar fuels under solar light.

10aC3N410aCO2 reduction10aFeWO410aPhotocatalysis10asolar fuels10aZ-scheme1 aBhosale, Reshma1 aJain, Srashti1 aVinod, Chathakudath, Prabhakara1 aKumar, Santosh1 aOgale, Satishchandra uhttp://library.ncl.res.in/content/direct-z-scheme-g-c3n4fewo4-nanocomposite-enhanced-and-selective-photocatalytic-co201939nas a2200229 4500008004100000022001400041245005900055210005900114260000800173300001400181490000700195520116800202100003001370700001901400700004801419700002501467700002501492700003201517700003601549700003101585856009301616 2020 eng d a0003-270000aGeometrical isomerism directed electrochemical sensing0 aGeometrical isomerism directed electrochemical sensing cMAR a4541-45470 v923 a

We report the independent role of isomerism of secondary sphere substituents over their nature, a factor often overlooked in molecular electrocatalysis pertaining to electrochemical sensing, by establishing that isomerism redefines the electronic structure at the catalytic reaction center via geometrical factors. UV-vis spectroscopy and X-ray photoelectron spectroscopy suggest that a substituent's isomerism in molecular catalysts conjoins molecular planarity and catalytic activation through competing field effects and resonance effects. As a classical example, we demonstrate the influence of isomerism of the -NO2 substituents for the electrocatalytic multi electron oxidation of As(III), a potentially important electrochemical pathway for water remediation and arsenic detection. The isomerism dependent oxidative activation of catalytic center leads to a nonprecious molecular catalyst capable for direct As(III) oxidation with an experimental detection limit close to WHO guidelines. This work opens up an unusual approach in analytical chemistry for developing various sensing platforms for challenging chemical and electrochemical reactions.

1 aKottaichamy, Alagar, Raja1 aBegum, Shabbah1 aDevendrachari, Mruthyunjayachar, Chattanaha1 aBhat, Zahid, Manzoor1 aThimmappa, Ravikumar1 aKotresh, Harish, Makri Nimb1 aVinod, Chathakudath, Prabhakara1 aThotiyl, Musthafa, Ottakam uhttp://library.ncl.res.in/content/geometrical-isomerism-directed-electrochemical-sensing01616nas a2200265 4500008004100000022001400041245010300055210006900158260000800227300001400235490000600249520073700255653001800992653002001010653001501030653000901045653003001054653000901084100002301093700002101116700002201137700003601159700002501195856013001220 2020 eng d a2574-096200aTweaking palladium electronic structure to attain oxygen reduction activity superior to platinum/C0 aTweaking palladium electronic structure to attain oxygen reducti cJUL a6127-61320 v33 a

Enhancing oxygen reduction (ORR) activity through alloying is crucial to improve the performance of a fuel-cell catalysts. In this work, we have studied the alloying effects of 4f rare-earth (RE) metals with palladium. The modified catalyst exhibits better activity (E-onset = 1 V and E-1/2 = 0.88 V) and higher selectivity toward H2O (similar to 97%) compared to the state-of-the-art catalysts due to complete dissociation of O-2. Hirshfeld charge analysis and 2D-electron localization function reveal improved adsorbate-adsorbent interaction on the catalyst surface. This work paves a strategy to design highly selective non-Pt-based catalysts for the ORR by controlling electronic structures and surface oxide formation.

10ad-band center10aDFT calculation10adurability10aEuPd10aoxygen reduction reaction10aYbPd1 aSarma, Saurav, Ch.1 aKaja, Sai, Manoj1 aMishra, Vidyanshu1 aVinod, Chathakudath, Prabhakara1 aPeter, Sebastian, C. uhttp://library.ncl.res.in/content/tweaking-palladium-electronic-structure-attain-oxygen-reduction-activity-superior-platinumc02182nas a2200253 4500008004100000022001400041245007600055210006900131260000900200300001200209490000700221520128000228100003001508700001901538700003401557700003201591700004901623700002501672700002501697700003201722700003601754700003101790856010701821 2020 eng d a1948-718500aUnprecedented isomerism-activity relation in molecular electrocatalysis0 aUnprecedented isomerismactivity relation in molecular electrocat cJAN  a263-2710 v113 a

The role of electrocatalysts in energy storage/conversion, biomedical and environmental sectors, green chemistry, and much more has generated enormous interest in comprehending their structure-activity relations. While targeting the surface-to-volume ratio, exposing reactive crystal planes and interfacial modifications are time-tested considerations for activating metallic catalysts; it is primarily by substitution in molecular electrocatalysts. This account draws the distinction between a substituent's chemical identity and isomerism, when regioisomerism of the -NO2 substituent is conferred at the ``alpha'' and ``beta'' positions on the macrocycle of cobalt phthalocyanines. Spectroscopic analysis and theoretical calculations establish that the beta isomer accumulates catalytically active intermediates via a cumulative influence of inductive and resonance effects. However, the field effect in the alpha isomer restricts this activation due to a vanishing resonance effect. The demonstration of the distinct role of isomerism in substituted molecular electrocatalysts for reactions ranging from energy conversion to biosensing highlights that isomerism of the substituents makes an independent contribution to electrocatalysis over its chemical identity.

1 aKottaichamy, Alagar, Raja1 aBegum, Shabbah1 aNazrulla, Mohammed, Azeezulla1 aDargily, Neethu, Christudas1 aDevendrachari, Mruthyunjayachari, Chattanaha1 aBhat, Zahid, Manzoor1 aThimmappa, Ravikumar1 aKotresh, Harish, Makri Nimb1 aVinod, Chathakudath, Prabhakara1 aThotiyl, Musthafa, Ottakam uhttp://library.ncl.res.in/content/unprecedented-isomerism-activity-relation-molecular-electrocatalysis02574nas a2200313 4500008004100000022001400041245013000055210006900185260000800254300001200262490000700274520150800281653003201789653001501821653002301836653001701859653002101876653002001897100002001917700002101937700002201958700002201980700001802002700001702020700003602037700003002073700003002103856012702133 2021 eng d a1614-683200aExceptional capacitance enhancement of a non-conducting COF through potential-driven chemical modulation by redox electrolyte0 aExceptional capacitance enhancement of a nonconducting COF throu cAPR a20036260 v113 a

Capacitors are the most practical high-storage and rapid charge-release devices. The number of ions stored per unit area and their interaction strength with the electrode dictates capacitor-performance. Microporous materials provide a high storage surface and optimal interactions. Adsorbing electron-rich and easily polarizable molecules into microporous electrodes is expected to boost Faradaic pseudo-activity. If such electrode-electrolyte interactions can be made as a potential-driven reversible process, the resulting capacitors would be adaptable and device-friendly. A composite covalent organic framework (COF)-carbon electrode with redox-active KI is combined in an H2SO4 electrolyte for the first time. This composite electrode benefits from the redox-functionality of COF and electronic conductivity of carbon, leading to superior capacitative activity. Operando spectro-electrochemical measurements reveal the existence of multiple polyiodide species, although the I-3(-) is the predominantly electroactive species adsorbing on the microporous triazine-phenol COF electrode. A systematic fabrication of the flexible solid-state devices using the COF-redox-electrolyte reveals a high areal capacitance of 270 +/- 11 mF cm(-2) and gravimetric capacitance of 57 +/- 8 F g(-1). The inclusion of KI in H2SO4 (electrolyte) yields an approximately eight-fold enhancement in solid-state gravimetric specific capacitance. The imine-COF retains 89% of its capacity even after 10 000 cycles.

10acovalent organic frameworks10apolyiodide10aredox electrolytes10asolid&\#820810astate capacitors10aSupercapacitors1 aKushwaha, Rinku1 aHaldar, Sattwick1 aShekhar, Pragalbh1 aKrishnan, Akshara1 aSaha, Jayeeta1 aHui, Pramiti1 aVinod, Chathakudath, Prabhakara1 aSubramaniam, Chandramouli1 aVaidhyanathan, Ramanathan uhttp://library.ncl.res.in/content/exceptional-capacitance-enhancement-non-conducting-cof-through-potential-driven-chemical02524nas a2200301 4500008004100000022001400041245011100055210006900166260000800235300001200243490000700255520151500262653002701777653002801804653001701832653002701849653002701876100002101903700001701924700002201941700001801963700003601981700001402017700002302031700001902054700003002073856011902103 2022 eng d a1614-683200aIncorporating conducting polypyrrole into a polyimide COF for carbon-free ultra-high energy supercapacitor0 aIncorporating conducting polypyrrole into a polyimide COF for ca cSEP a22007540 v123 a

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'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.

10acarbon free capacitors10acation-anion co-storage10aconductivity10ahigh energy capacitors10apolypyrrole doped COFs1 aHaldar, Sattwick1 aRase, Deepak1 aShekhar, Pragalbh1 aJain, Chitvan1 aVinod, Chathakudath, Prabhakara1 aZhang, En1 aShupletsov, Leonid1 aKaskel, Stefan1 aVaidhyanathan, Ramanathan uhttp://library.ncl.res.in/content/incorporating-conducting-polypyrrole-polyimide-cof-carbon-free-ultra-high-energy01843nas a2200193 4500008004100000245008400041210006900125260000900194300001100203490000700214520111300221100002901334700004901363700002401412700003601436700003201472700003101504856011401535 2022 eng d00aRegio-isomerism directed electrocatalysis for energy efficient zinc-air battery0 aRegioisomerism directed electrocatalysis for energy efficient zi cOCT  a1051790 v253 a

We have investigated the role of ligand isomerism in modulating the mechanisms and kinetics associated with charge/ discharge chemistry of an aqueous metal-air battery. The dominant electron-withdrawing inductive effect (-I effect) and the diminished electron-withdrawing resonance effect (-R effect) in the alpha-NO2 isomer noticeably diminishes the rate of oxygen reduction (ORR) and oxygen evolution reactions (OER) on the catalytic Co-center. In their beta-counterpart, the cumulative -I and -R effects noticeably enhance the OER and ORR kinetics on the same catalytic Co-center. Therefore, the regioisomerism of the -NO2 functionality amplifies the kinetics of ORR/OER without influencing their mechanistic pathways. When isomeric electrocatalysts are integrated to aid the charge chemistry of a Zn-air battery, the overpotential could be decreased by similar to 250mV with beta-NO2 isomer leading to a round-trip efficiency as high as 60%. This work contributes to the design of novel molecular platforms to target the overall round-trip efficiency of energy storage and conversion devices.

1 aMukhopadhyay, Sanchayita1 aDevendrachari, Mruthyunjayachari, Chattanaha1 aKanade, Sandeep, C.1 aVinod, Chathakudath, Prabhakara1 aKotresh, Harish, Makri Nimb1 aThotiyl, Musthafa, Ottakam uhttp://library.ncl.res.in/content/regio-isomerism-directed-electrocatalysis-energy-efficient-zinc-air-battery02843nas a2200301 4500008004100000245017400041210006900215260000900284300001400293490000600307520174100313653001202054653001402066653003102080653002802111653001802139653002402157100003702181700002002218700001802238700002202256700002202278700002602300700003602326700003002362700001802392856013102410 2022 eng d00aSynergistic electronic effects in AuCo nanoparticles stabilized in a triazine-based covalent organic framework: a catalyst for methyl orange and methylene blue reduction0 aSynergistic electronic effects in AuCo nanoparticles stabilized  cAPR  a4744-47530 v53 a

Developing stable active catalysts for reducing water-soluble pollutants is a desirable target. In this pursuit, we have functionalized covalent organic frameworks (COFs) with gold (Au) and cobalt (Co) nanoparticles via a one-step aqueous synthesis process, and their catalytic activity in reducing methyl orange and methylene blue is examined. Operando absorbance measurements of methyl orange (anionic dye) reduction revealed AuCoCOF (1.3 Au/1.0 Co) to have superior kinetics over many other catalysts, which typically require additional external stimuli (e.g., photons) and higher catalyst loadings. After confirming the homogeneous dispersion of the nanoparticles on the COF support using three-dimensional (3D) tomography and material stability through powder X-ray diffraction (PXRD), infrared (IR), and thermal studies, we investigated their redox activity. Cyclic voltammetry (CV) confirmed the involvement of both metals in the redox process, while spectroelectrochemical measurements show that their activity and kinetics remain unaltered by an applied potential. Solid-state UV measurements reveal that the neat COF is a semiconductor with a large band gap (2.8 eV), which is substantially lowered when loaded with cobalt nanoparticles (2.2 eV for CoCOF). The electronic synergy between Au and Co nanoparticles further reduces the band gap of AuCoCOF (1.9 eV). Thus, there is a definite advantage in doping non-noble metal nanoparticles into a noble metal lattice and nanoconfining them into a porous COF support. Our study highlights the significance of bimetallic COF-supported nanocatalysts, wherein one can engage each component toward targeted applications that demand redox activity with favorable kinetics.

10aAuCoCOF10aband gaps10aCovalent organic framework10amethyl orange reduction10aNanoparticles10aUV-vis spectroscopy1 aDevulapalli, Venkata, Swaroopa D1 aKushwaha, Rinku1 aOvalle, Edwin1 aSingh, Himan, Dev1 aShekhar, Pragalbh1 aChakraborty, Debanjan1 aVinod, Chathakudath, Prabhakara1 aVaidhyanathan, Ramanathan1 aBorguet, Eric uhttp://library.ncl.res.in/content/synergistic-electronic-effects-auco-nanoparticles-stabilized-triazine-based-covalent-organic02408nas a2200289 4500008004100000022001400041245011300055210006900168260000800237490000700245520141200252653003201664653002301696653001501719653002301734653002101757100002001778700001801798700002201816700001701838700002701855700001601882700002301898700003601921700003001957856013101987 2023 eng d a1614-683200aMade to measure squaramide COF cathode for zinc dual-ion battery with enriched storage via redox electrolyte0 aMade to measure squaramide COF cathode for zinc dualion battery  cSEP0 v133 a

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'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.

10acovalent organic frameworks10aflexible batteries10apolyiodide10aredox electrolytes10aZn ion batteries1 aKushwaha, Rinku1 aJain, Chitvan1 aShekhar, Pragalbh1 aRase, Deepak1 aIllathvalappil, Rajith1 aMekan, Deep1 aCamellus, Augastus1 aVinod, Chathakudath, Prabhakara1 aVaidhyanathan, Ramanathan uhttp://library.ncl.res.in/content/made-measure-squaramide-cof-cathode-zinc-dual-ion-battery-enriched-storage-redox-electrolyte02035nas a2200265 4500008004100000022001400041245008900055210006900144260000800213300001400221490000700235520109600242100003001338700002601368700001401394700003401408700001601442700002501458700004901483700003601532700003201568700002201600700003101622856011601653 2023 eng d a2041-652000aUnprecedented energy storage in metal-organic complexes via constitutional isomerism0 aUnprecedented energy storage in metalorganic complexes via const cJUN a6383-63920 v143 a

The essence of any electrochemical system is engraved in its electrical double layer (EDL), and we report its unprecedented reorganization by the structural isomerism of molecules, with a direct consequence on their energy storage capability. Electrochemical and spectroscopic analyses in combination with computational and modelling studies demonstrate that an attractive field-effect due to the molecule's structural-isomerism, in contrast to a repulsive field-effect, spatially screens the ion-ion coulombic repulsions in the EDL and reconfigures the local density of anions. In a laboratory-level prototype supercapacitor, those with beta-structural isomerism exhibit nearly 6-times elevated energy storage compared to the state-of-the-art electrodes, by delivering similar to 535 F g(-1) at 1 A g(-1) while maintaining high performance metrics even at a rate as high as 50 A g(-1). The elucidation of the decisive role of structural isomerism in reconfiguring the electrified interface represents a major step forward in understanding the electrodics of molecular platforms.

1 aKottaichamy, Alagar, Raja1 aDeebansok, Siraprapha1 aDeng, Jie1 aNazrulla, Mohammed, Azeezulla1 aZhu, Yachao1 aBhat, Zahid, Manzoor1 aDevendrachari, Mruthyunjayachari, Chattanaha1 aVinod, Chathakudath, Prabhakara1 aKotresh, Harish, Makri Nimb1 aFontaine, Olivier1 aThotiyl, Musthafa, Ottakam uhttp://library.ncl.res.in/content/unprecedented-energy-storage-metal-organic-complexes-constitutional-isomerism