01844nas a2200193 4500008004100000245008400041210006900125260000900194300001100203490000700214520111300221100002901334700004901363700002401412700003601436700003201472700003101504856011501535 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 uhttps://library.ncl.res.in/content/regio-isomerism-directed-electrocatalysis-energy-efficient-zinc-air-battery01948nas a2200229 4500008004100000022001400041245009900055210006900154260000900223300001400232490000700246520110500253100002901358700003001387700003001417700002101447700003601468700003201504700002401536700003101560856012701591 2023 eng d a1948-718500aUnusual ligand assistance in molecular electrocatalysis via interfacial proton charge assembly0 aUnusual ligand assistance in molecular electrocatalysis via inte cJUN  a5377-53850 v143 a

We show that the ability of the ligand to reorganizethe electricdouble layer (EDL) often dominates the electrocatalysis contrary totheir inductive effect in the spectrochemical series, leading to counterintuitiveelectrocatalysis. With water oxidation and chlorine evolution as theprobe reactions, the same catalytic entity with carboxy functionalizedligand exhibited surprisingly higher electrochemical activity in comparisonto the aggressively electron-withdrawing nitro functionalized ligands,which is contrary to their actual location in the spectrochemicalseries. Spectroscopic and electrochemical analyses suggest the enrichmentof catalytically active species in the carboxy substituted ligandvia proton charge assembly in the EDL that in turn enhances the kineticsof the overall electrochemical process. This demonstration of lessobvious ligands becoming indispensable in electrocatalysis suggestsa blind designing of ligands solely based on their inductive effectshould be reconsidered as it will prevent the utilization of the maximumpotential of the molecule in electrocatalysis.

1 aMukhopadhyay, Sanchayita1 aKottaichamy, Alagar, Raja1 aChame, Pallavi, Vyankuram1 aGhosh, Prasenjit1 aVinod, Chathakudath, Prabhakara1 aKotresh, Harish, Makri Nimb1 aKanade, Sandeep, C.1 aThotiyl, Musthafa, Ottakam uhttps://library.ncl.res.in/content/unusual-ligand-assistance-molecular-electrocatalysis-interfacial-proton-charge-assembly01780nas a2200217 4500008004100000022001400041245011300055210006900168260000900237300001400246490000700260520093400267100002901201700003001230700004901260700002701309700003201336700003601368700003101404856012701435 2024 eng d a2041-652000aElectrochemical energy storage in an organic supercapacitor via a non-electrochemical proton charge assembly0 aElectrochemical energy storage in an organic supercapacitor via  cJAN  a1726-17350 v153 a

Contrary to conventional beliefs, we show how a functional ligand that does not exhibit any redox activity elevates the charge storage capability of an electric double layer via a proton charge assembly. Compared to an unsubstituted ligand, a non-redox active carboxy ligand demonstrated nearly a 4-fold increase in charge storage, impressive capacitive retention even at a rate of 900C, and approximately a 2-fold decrease in leakage currents with an enhancement in energy density up to approximately 70% via a non-electrochemical route of proton charge assembly. Generalizability of these findings is presented with various non-redox active functional units that can undergo proton charge assembly in the ligand. This demonstration of non-redox active functional units enriching supercapacitive charge storage via proton charge assembly contributes to the rational design of ligands for energy storage applications.

1 aMukhopadhyay, Sanchayita1 aKottaichamy, Alagar, Raja1 aDevendrachari, Mruthyunjayachari, Chattanaha1 aMendhe, Rahul, Mahadeo1 aKotresh, Harish, Makri Nimb1 aVinod, Chathakudath, Prabhakara1 aThotiyl, Musthafa, Ottakam uhttps://library.ncl.res.in/content/electrochemical-energy-storage-organic-supercapacitor-non-electrochemical-proton-charge00889nas a2200277 4500008004100000022001400041245004200055210004200097260000900139300001600148490000700164653001800171653002600189653002000215653002100235100001800256700003000274700003200304700002900336700002100365700004900386700003600435700003200471700003100503856007700534 2024 eng d a2041-652000aSwitchable molecular electrocatalysis0 aSwitchable molecular electrocatalysis cAUG  a13262-132700 v1510aCO2 reduction10aCOBALT PHTHALOCYANINE10aNANOPOROUS GOLD10aoxygen reduction1 aDutt, Shifali1 aKottaichamy, Alagar, Raja1 aDargily, Neethu, Christudas1 aMukhopadhyay, Sanchayita1 aNayak, Bhojkumar1 aDevendrachari, Mruthyunjayachari, Chattanhal1 aVinod, Chatakudhath, Prabakaran1 aKotresh, Harish, Makri Nimb1 aThotiyl, Musthafa, Ottakam uhttps://library.ncl.res.in/content/switchable-molecular-electrocatalysis02439nas a2200229 4500008004100000022001400041245014500055210006900200260000900269300001600278490000700294520156000301100001901861700002901880700001901909700002101928700003201949700003201981700003602013700003102049856012902080 2024 eng d a1477-922600aSynergistic effects of the substrate-ligand interaction in metal-organic complexes on the de-electronation kinetics of a vitamin C fuel cell0 aSynergistic effects of the substrateligand interaction in metalo cAUG  a13384-133930 v533 a

The rising demand for portable energy conversion devices has spurred the advancement of direct liquid fuel cells (DLFCs) employing fuels such as alcohol, ammonia, hydrazine, and vitamin C. In these devices, various precious metal platforms have been explored to increase the de-electronation kinetics and reduce catalyst poisoning, but with substantial cost implications. We demonstrate the crucial role of ligands in non-precious organometallic complexes in influencing the de-electronation kinetics of fuel molecules through a unique substrate-ligand synergistic interaction. This unique chemistry imparts electron deficiency at the catalytic metal center while simultaneously populating the ligand with an extensive proton charge assembly. This distinct substrate-ligand interaction enhances the DLFC performance by coulombically dragging the substrate with a distinct amplification in its de-electronation kinetics. By integrating this approach with a ferricyanide/ferrocyanide half-cell reaction, a precious metal-free vitamin C fuel cell is developed, which is capable of generating an open circuit voltage of similar to 950 mV, a peak power density of similar to 97 mW cm-2 at a peak current density of similar to 215 mA cm-2 with the performance metrics nearly 1.7 times higher than a precious metal based DLFC. This highlights the potential of the substrate-ligand synergy in the design of efficient molecular catalysts for energy conversion applications. A precious metal-free biomass fuel cell through substrate-ligand interactions.

1 aParmar, Muskan1 aMukhopadhyay, Sanchayita1 aMondal, Ritwik1 aNayak, Bhojkumar1 aDargily, Neethu, Christudas1 aKotresh, Harish, Makri Nimb1 aVinod, Chathakudath, Prabhakara1 aThotiyl, Musthafa, Ottakam uhttps://library.ncl.res.in/content/synergistic-effects-substrate-ligand-interaction-metal-organic-complexes-de-electronation