01957nas a2200229   4500008004100000022001400041245010000055210006900155260000800224300001200232490000800244520121400252653001201466653000801478653001801486653001601504653002401520100002001544700001901564700001801583856012601601       2019                        eng d  a0039-602800aNature of electrophilic oxygen: insights from periodic density functional theory investigations0 aNature of electrophilic oxygen insights from periodic density fu  cJAN  a188-1950 v6793 a<p>Increasing demand of ethylene oxide and the cost of versatile chemical ethene has been a driving force for understanding mechanism of epoxidation to develop highly selective catalytic process. Direct epoxidation is a proposed mechanism which in theory provides 100% selectivity. A key aspect of this mechanism is an electrophilic oxygen (O-ele) species forming on the Ag surface. In the past two and half decades, large number of theoretical and experimental investigations have tried to elucidate formation of O-ele, on Ag surface with little success. Equipped with this rich literature on Ag-O interactions, we investigate the same using periodic DFT calculations to further understand how silver surface and oxygen interact with each other from a chemical standpoint. Based on energetics, Lowdin charges, topologies and pdos data described in this study, we scrutinize the established notions of O-ele. Our study provides no evidence in support of O-ele, being an atomic species nor a diatomic molecular species. In fact, a triatomic molecular species described in this work bears multiple signatures which are very convincing evidence for considering it as the most sought for electrophilic entity.</p>10aAg(100)10aDFT10aElectrophilic10aepoxidation10aNucleophilic oxygen1 aKenge, Nivedita1 aPitale, Sameer1 aJoshi, Kavita  uhttps://library.ncl.res.in/content/nature-electrophilic-oxygen-insights-periodic-density-functional-theory-investigations02043nas a2200265   4500008004100000022001400041245007100055210006900126260000800195300001100203490000800214520127000222653000801492653000901500653002901509653001201538100001801550700002001568700002001588700002501608700001701633700001301650700001801663856009601681       2020                        eng d  a0169-433200aMixed metal oxide: a new class of catalyst for methanol activation0 aMixed metal oxide a new class of catalyst for methanol activatio  cDEC  a1474490 v5343 a<p>In this work, we propose a mixed metal oxide as a catalyst and demonstrate it's ability to not only activate the MeOH molecule upon adsorption but also dissociate O-H and one of it's C-H bonds. MeOH activation is compared on two prominent facets of ZnAl(2)O(4 )viz. (2 2 0) and (31 1). While spontaneous O-H bond dissociation is observed on both facets, C-H bond dissociates only on the (3 1 1) surface. Multiple factors like atomic arrangement and steps on the surface, coordination of surface atoms, and their effective charges have a combined effect on MeOH activation. The (3 1 1) surface offers higher catalytic activity in comparison with (2 2 0) surface. Having a stepped surface, availability of multiple sites, and variation in the charge distribution are some of the reasons for better catalytic performance of (3 1 1) facet. Effect of orientation of MeOH with respect to the surface adds both, information and complexity to the problem. Observations pertinent to understanding this effect are also reported. A detailed analysis of atomic arrangement on the two surfaces provides a rationale as to why MeOH gets dissociated spontaneously on the mixed metal oxide. The promising results reported here opens up a new class of catalyst for research.</p>
10aDFT10aMeOH10aSpontaneous dissociation10aZnAl2O41 aMehta, Shweta1 aAgarwal, Sheena1 aKenge, Nivedita1 aMekala, Siva, Prasad1 aPatil, Vipul1 aRaja, T.1 aJoshi, Kavita  uhttps://library.ncl.res.in/content/mixed-metal-oxide-new-class-catalyst-methanol-activation02064nas a2200205   4500008004100000022001400041245010300055210006900158260000800227300001100235490000800246520139700254653000801651653000901659653002501668653000801693100001801701700001801719856012101737       2022                        eng d  a0169-433200aFrom molecular adsorption to decomposition of methanol on various ZnO facets: a periodic DFT study0 aFrom molecular adsorption to decomposition of methanol on variou  cNOV  a1541500 v6023 a<p>
	Methanol is an interesting and important molecule to study because of its potential to replace existing fuels. It is also a prominent hydrogen source which can be used to generate hydrogen in-situ. ZnO is widely used as catalyst in synthesis of methanol from CO2 at industrial scale. In this work, we demonstrate that the same catalyst could be used for MeOH decomposition. We have investigated interaction of methanol with various flat and stepped facets of ZnO by employing Density Functional Theory (DFT). Two flat [(10(1)overbar 0) and (11(2)overbar 0)] and two stepped [(10(1)overbar 3) and (11(2)overbar 2)] facets are studied in detail for methanol adsorption. Chemisorption of MeOH with varying strength is common to all four facets. Most importantly spontaneous dissociation of O-H bond of methanol is observed on all facets except (11(2)overbar 0). Our DFT calculations reveal that molecular adsorption is favored on flat facets, while dissociation is favored on step facets. Also, (10(1)overbar 0) facet undergoes substantial reconstruction upon MeOH adsorption. Activation of C-H bond along with strengthening of C-O bond on ZnO facets suggest partial oxidation of methanol. With our DFT investigations, we dig deeper into the underlying electronic structure of various facets of ZnO and provide rationale for the observed facet dependent interaction of ZnO with MeOH.</p>
10aDFT10aMeOH10aSurface interactions10aZnO1 aMehta, Shweta1 aJoshi, Kavita  uhttps://library.ncl.res.in/content/molecular-adsorption-decomposition-methanol-various-zno-facets-periodic-dft-study02048nas a2200217   4500008004100000022001400041245010000055210006900155260000800224300001500232490000600247520131900253653002201572653002601594653001401620653000801634653002101642100002001663700001801683856012901701       2022                        eng d  a2365-654900aLooking beyond adsorption energies to understand interactions at surface using machine learning0 aLooking beyond adsorption energies to understand interactions at  cOCT  ae2022024140 v73 a<p>
	Identifying factors that influence interactions at the surface is still an active area of research. In this work, the importance of analyzing bond length activations (BLact) along with adsorption energies (E-a) while interpreting Density Functional Theory (DFT) results is emphasized. Investigating adsorption of different small molecules, such as O-2, N-2, CO, and CO2, on commonly studied facets ((100), (110), and (111)) of seven fcc transition metal surfaces (M=Ag, Au, Cu, Ir, Rh, Pt, and Pd) demonstrates the missing linear correlation between E-a and BLact. Further, tree based Machine Learning (ML) models reinforce the missing linear correlation between the two parameters and also highlight the importance of analyzing both to develop a better understanding of adsorption at surfaces. The best performing Random Forest models have a mean absolute error (MAE) of 0.19 eV for E-a prediction, and even lower MAE of 0.012 angstrom for BLact prediction. While often d-band center is correlated with E-a, our observations show that infact the d-band center has a better correlation with BLact. These observations emphasizes the role of BLact in gaining a fuller picture for catalysis. The fact that the factors responsible for BLact is a lesser-explored subject adds to the novelty of the findings.</p>
10aAdsorption energy10aBondlength activation10acatalysis10aDFT10amachine learning1 aAgarwal, Sheena1 aJoshi, Kavita  uhttps://library.ncl.res.in/content/looking-beyond-adsorption-energies-understand-interactions-surface-using-machine-learning02009nas a2200241   4500008004100000022001400041245006900055210006900124260000800193300001100201490000800212520131900220653001201539653001201551653000801563653001601571653002501587653000801612100001801620700002001638700001801658856009101676       2022                        eng d  a0039-602800aRole of facet in the competitive pathway of ethylene epoxidation0 aRole of facet in the competitive pathway of ethylene epoxidation  cFEB  a1219540 v7163 aEthylene epoxide (EtO) is used as raw material for a broad range of products from pharmaceuticals and plastics to paints and adhesives. Although the reaction of ethylene interacting with preadsorbed oxygen on Ag surface is known for decades, the underlying mechanism of EtO formation is not completely understood. Successful investigation of oxametallacycle (OMC) intermediate common to selective as well as non-selective pathways has ensured at least 50% selectivity. The current study brings out the electronic signatures of distinct conformers of OMC stabilised on two different facets of Ag viz. (100) and (111). There are subtle differences between OMC conformers observed on these two facets with near-eclipsed on Ag(100) and near-staggered on Ag(111). A detailed analysis of Ag-O, C-O, C-C, and Ag-C interactions along with projected Density of States (pDOS) and projected Crystal Orbital Hamilton Population (pCOHP) imply towards ring closure on Ag(100) and hydrogen transfer on Ag(111). Finally, our understanding based on electronic and structural signatures are backed up by activation barriers computed through NEB calculations. Activation barrier for EtO is lower on (100) as compared to (111) facet. Thus, our study sheds light on how these differences between OMC affect the selectivity towards EtO.10aAg(100)10aAg(111)10aDFT10aepoxidation10aEthylene Oxide (EtO)10aOMC1 aNair, Aathira1 aKenge, Nivedita1 aJoshi, Kavita  uhttps://library.ncl.res.in/content/role-facet-competitive-pathway-ethylene-epoxidation01605nas a2200217   4500008004100000022001400041245009500055210006900150260000800219300001100227490000800238520091100246653000801157653002601165653001301191653002101204653000801225100001801233700001801251856011801269       2023                        eng d  a0039-602800aElectronic fingerprints for diverse interactions of methanol with various Zn-based systems0 aElectronic fingerprints for diverse interactions of methanol wit  cOCT  a1223500 v7363 a<p>
	We have investigated various Zn-based catalysts for their interaction with methanol (MeOH). MeOH is one of the most critical molecules being studied extensively, and Zn-based catalysts are widely used in many industrially relevant reactions involving MeOH. We note that the same element (Zn and O, in the present study) exhibits different catalytic activity in different environments. The changing environment is captured in the underlying electronic structure of the catalysts. In the present work, we compared the electronic structure of Zn-based systems, i.e., ZnAl2O4 and ZnO along with oxygen preadsorbed Zn (O-Zn) and metallic Zn. We demonstrate the one-to-one correlation between the pDOS of the bare facet and the outcome of that facet's interaction (i.e. either adsorption or dissociation of MeOH) with MeOH. These findings would pave the way towards the in-silico design of catalysts.</p>
10aDFT10aElectronic properties10aMethanol10aZn-based systems10aZnO1 aMehta, Shweta1 aJoshi, Kavita  uhttps://library.ncl.res.in/content/electronic-fingerprints-diverse-interactions-methanol-various-zn-based-systems02813nas a2200253   4500008004100000022001400041245008900055210006900144260000800213300001600221490000700237520198700244653000802231653003302239653002302272653001602295653002602311653002802337100002002365700001802385700001802403700001902421856011902440       2023                        eng d  a0360-319900aHydrogen from catalytic non-thermal plasma-assisted steam methane reforming reaction0 aHydrogen from catalytic nonthermal plasmaassisted steam methane   cJUL  a24328-243410 v483 a<p>
	Steam methane reforming reaction was carried out in a dielectric barrier plasma reactor. A systematic study is conducted to understand the influence of input power, flow rate, and water for the conversion, yield, and selectivity of the reaction over strategically designed catalysts. In particular, the production rate and selectivity of the products (H2, CO and C2 hydrocarbons) are monitored. CeO2 was used as packing material, mixed with oxides of manganese or copper and their combination. The optimum Cu/CeO2 catalyst illustrated the production rate of 248.7 mmolg-1h-1 and 11.25 mmolg-1h-1 for H2, and CO, respectively at specific energy input of 19.8 JL-1. DFT calculations exhibit apparent change in electronic structure of the CeO2 after inclusion of oxides of manganese and copper that enhance interaction with methane. Based on these findings, a plausible mechanism is elucidatedSteam methane reforming reaction was carried out in a dielectric barrier plasma reactor. A systematic study is conducted to understand the influence of input power, flow rate, and water for the conversion, yield, and selectivity of the reaction over strategically designed catalysts. In particular, the production rate and selectivity of the products (H2, CO and C2 hydrocarbons) are monitored. CeO2 was used as packing material, mixed with oxides of manganese or copper and their combination. The optimum Cu/CeO2 catalyst illustrated the production rate of 248.7 mmolg-1h-1 and 11.25 mmolg-1h-1 for H2, and CO, respectively at specific energy input of 19.8 JL-1. DFT calculations exhibit apparent change in electronic structure of the CeO2 after inclusion of oxides of manganese and copper that enhance interaction with methane. Based on these findings, a plausible mechanism is elucidated which can help to design catalyst for other applications in non-thermal plasma atmosphere. &amp; COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.</p>
10aDFT10aDielectric barrier discharge10aNon-thermal plasma10aselectivity10aSpecific energy input10aSteam methane reforming1 aBajpai, Abhinav1 aMehta, Shweta1 aJoshi, Kavita1 aKumar, Sushant  uhttps://library.ncl.res.in/content/hydrogen-catalytic-non-thermal-plasma-assisted-steam-methane-reforming-reaction01865nas a2200193   4500008004100000022001400041245010100055210006900156260000900225490000800234520121600242653002201458653000801480653001001488653001001498100002001508700001801528856012501546       2024                        eng d  a2468-823100aExploring the catalytic potential of Mg-Cu alloys for enhanced activity toward CO2 hydrogenation0 aExploring the catalytic potential of MgCu alloys for enhanced ac  cMAR 0 v5563 a<p>
	CO2, a well-known greenhouse gas, is a potential raw material that can produce various chemicals. Dissociation of CO2 to CO or hydrogenation to formate (HCOO*) or carboxyl (COOH*) intermediate is crucial in determining the reaction pathway for CO2 conversion. In this work, we demonstrate that alloys of Mg-Cu exhibit greater activity toward activation and hydrogenation of CO2 than transition metal alloys reported so far. Two different compositions of Mg-Cu, namely Mg2Cu and MgCu2, have been studied using periodic Density Functional Theory (DFT). Our investigations reveal that CO2 chemisorbs on both intermetallic alloys. Coadsorption of CO2 with H2O leads to the spontaneous formation of COOH* over Mg2Cu(224), whereas a negligible barrier (0.04 eV) is observed for MgCu2(311). HCOO* formation has a barrier of 0.34 eV and 0.42 eV on Mg2Cu(224) and MgCu2(311), respectively. Dissociation of CO2 to CO is kinetically unfavourable on both compositions of Mg-Cu. We provide a rationale for the observed activity by analyzing the electronic structure. Notably, the spontaneous hydrogenation of CO2 makes earth -abundant metals suitable candidates for alloying that await experimental verification.</p>
10aCO2 hydrogenation10aDFT10aMg2Cu10aMgCu21 aThakkar, Kavita1 aJoshi, Kavita  uhttps://library.ncl.res.in/content/exploring-catalytic-potential-mg-cu-alloys-enhanced-activity-toward-co2-hydrogenation01960nas a2200229   4500008004100000022001400041245009500055210006900150260000900219300001100228490000800239520124200247653000801489653001701497653000901514653000801523100001801531700002001549700002801569700001801597856011501615       2024                        eng d  a0169-433200aFrom digital blueprint to chemical reality: methanol to formaldehyde at ambient conditions0 aFrom digital blueprint to chemical reality methanol to formaldeh  cOCT   a1605270 v6693 a<p>
	Partial oxidation of methanol to value added product presents an intriguing yet challenging process. Among these products, formaldehyde is the simplest and one of the most vital aliphatic aldehydes, which has extensive application across various domains. Industrially, silver and iron-molybdenum oxides are used as catalysts for the conversion of methanol to formaldehyde at elevated temperatures (600 degrees C and 250-400 degrees C, respectively). However, in this computational and experimental study, we have demonstrated the efficacy of ZnO as a catalyst. Notably, in the presence of ZnO, methanol readily converts to formaldehyde even under ambient conditions. We employed periodic density functional theory (DFT) to explore (10 1 1) facet of ZnO to elucidate its interaction with methanol. Our comprehensive analysis identified the most active facet (10 1 1) involved in the spontaneous conversion of methanol to formaldehyde. Subsequently, experimental validation supported our theoretical findings, demonstrating the conversion of methanol to formaldehyde with 100% selectivity at room temperature and atmospheric pressure in the presence of ZnO. This study exemplifies the pivotal role of theory in catalyst design.</p>
10aDFT10aFormaldehyde10aMeOH10aZnO1 aMehta, Shweta1 aKasabe, Mirabai1 aUmbarkar, Shubhangi, B.1 aJoshi, Kavita  uhttps://library.ncl.res.in/content/digital-blueprint-chemical-reality-methanol-formaldehyde-ambient-conditions02221nas a2200241   4500008004100000022001400041245015300055210006900208260000800277520129500285653004401580653000801624653002401632653002701656653002901683100004001712700001801752700001901770700001801789700001801807700002401825856013001849       2024                        eng d  a1613-681000aInsights on prussian blue analogue cathode material engineered with polypyrrole surface protection layer for aqueous rechargeable zinc metal battery0 aInsights on prussian blue analogue cathode material engineered w  cNOV3 a<p>
	One of the key intricacies against using Prussian blue analogues (PBAs) in aqueous batteries is their gradual dissolution in aqueous electrolytes, resulting in inadequate cycling stability. Besides, the rate capability of PBAs is limited due to their poor electrical conductivity. To overcome these challenges, it is essential to tune the physical and chemical properties of PBAs at the nano regime without affecting the inherent charge storage properties, especially at high-voltage operating conditions. Through this work, a strategy is demonstrated to enhance the electrochemical performance of vanadium-based PBA (V-PBA) by surface engineering using a conducting polymer nano-skin (V-PBA/PPy) for aqueous zinc metal batteries. The polypyrrole (PPy) nano-skin over the V-PBA nanoparticles acts as an electron percolation path to ameliorate the poor electronic conductivity of the otherwise pristine V-PBA. Interestingly, the V-PBA with an optimized polypyrrole coating (V-PBA/PPy-2) exhibits an enhanced specific capacity (173 mAh g-1 at 0.10 A g-1) than the pristine V-PBA counterpart (80 mAh g-1) and 85% capacity retention up to 500 cycles. The DFT calculation confirms the synergistic interaction between PPy and V-PBA and the presence of PPy favors the adsorption of Zn.</p>
10aaqueous rechargeable zinc metal battery10aDFT10apolypyrrole coating10aPrussian blue analogue10asurface protection layer1 aPuthiyaveetil, Priyanka, Pandinhare1 aNair, Aathira1 aDilwale, Swati1 aKurian, Maria1 aJoshi, Kavita1 aKurungot, Sreekumar  uhttps://library.ncl.res.in/content/insights-prussian-blue-analogue-cathode-material-engineered-polypyrrole-surface-protection01655nas a2200193   4500008004100000022001400041245010800055210006900163260000800232490000800240520099200248653000801240653001201248653000801260653002601268100002001294700001801314856012901332       2024                        eng d  a1093-326300aSingle-atom alloys of Cu(211) with earth-abundant metals for enhanced activity towards CO2 dissociation0 aSingleatom alloys of Cu211 with earthabundant metals for enhance  cJAN0 v1263 a<p>CO2, a byproduct from various industrial reactions, must not be released into the atmosphere and should be managed through capture, conversion, and utilization. The first step in converting CO2 into valuable products is to break the C-O bond. This work focuses on designing Single Atom Catalysts (SACs) by doping Cu(211) surface with 13 different s, p, and d block elements with an aim to minimize the activation barrier for C-O bond cleavage. Our work demonstrates that SACs of Mg/Al/Pt@Cu(211) favor CO2 chemisorption compared to Cu(211) where CO2 physisorbs. The barrier for CO2 dissociation is lowest for Mg@Cu(211) and it increases in the order Mg@Cu(211) &lt; Al@Cu(211) &lt; Pt@Cu(211) &lt; Zn@Cu(211) &lt; Ga@Cu(211) &lt; Cu@Cu(211) &lt; Pd@Cu(211). These findings suggest that doping Cu(211) with earth-abundant metal like Mg can potentially be a viable catalyst for CO2 conversion, providing a promising solution to reduce carbon footprint and mitigate climate change.</p>
10aCO210aCu(211)10aDFT10aSingle atom catalysts1 aThakkar, Kavita1 aJoshi, Kavita  uhttps://library.ncl.res.in/content/single-atom-alloys-cu211-earth-abundant-metals-enhanced-activity-towards-co2-dissociation01990nas a2200217   4500008004100000022001400041245013800055210006900193260000800262490000800270520122900278653001201507653000801519653002301527653002501550653002501575653000801600100001801608700001801626856012801644       2024                        eng d  a0927-025600aWhat leads to direct epoxidation? an exhaustive DFT investigation of electrophilic oxygen mediated epoxidation of ethylene on Ag(100)0 aWhat leads to direct epoxidation an exhaustive DFT investigation  cAPR0 v2393 a<p>
	Extensive research has contributed to a better understanding of the commercially important epoxidation reaction. Selectivity, a crucial aspect of this reaction, has received significant attention in both experimental and theoretical investigations. However, a consensus regarding the role of electrophilic oxygen in epoxidation is yet to be reached. The present study is a theoretical examination of the prerequisites necessary for direct epoxidation to occur on the Ag(100) surface, at varied monolayer concentrations. Additionally, the study investigates the characteristics of various oxygen species interacting with ethylene to promote the direct epoxidation pathway. Based on the effective charges and projected density of states (pDOS) analysis, three oxygen variants were identified on the Ag(100) surface: atomic oxygen, dissociatively adsorbed molecular oxygen, and O 3 . The investigation reveals that all oxygen species, despite their physical and electronic differences, are electrophilic and undergo direct epoxidation. This work provides insights into the complex nature of epoxidation reaction and discusses electronic factors influencing the selective oxidation route on different Ag-O complexes.</p>
10aAg(100)10aDFT10aDirect epoxidation10aElectrophilic oxygen10aEthylene Oxide (EtO)10aOMC1 aNair, Aathira1 aJoshi, Kavita  uhttps://library.ncl.res.in/content/what-leads-direct-epoxidation-exhaustive-dft-investigation-electrophilic-oxygen-mediated