01259nas a2200169 4500008004100000022002200041245003700063210003700100250000600137260001400143300001200157520079700169100001800966700001900984700001801003856006801021 2017 eng d a978-3-319-68052-100aModel nanoparticles in catalysis0 aModel nanoparticles in catalysis a1 b Springer a165-1993 a

The importance of surface structure in catalysis is well documented by a large volume of surface science studies carried out on single crystal surfaces. Recent years has seen rapid strides in the synthesis of structured nanomaterials with varying morphologies and architecture. There is a growing interest in utilizing model nanoparticles like morphology-controlled nanostructures and core–shell-like bimetallic nanoparticles in catalysis. Apart from showing unprecedented reactivity, they serve as a model surfaces to answer many fundamental question in catalysis and also to arrive at structure vs activity correlations in heterogeneous catalysis. This chapter gives an introduction to such nanomaterials and recent advances in utilizing these materials for catalytic applications.

1 aVinod, C., P.1 aVysakh, A., B.1 aSreedhala, S. uhttp://library.ncl.res.in/content/model-nanoparticles-catalysis02472nas a2200265 4500008004100000022001400041245008800055210006900143260000800212300001600220490000600236520163300242653001701875653001801892653003101910653002501941100001801966700001901984700001802003700002002021700002402041700001602065700001802081856010702099 2019 eng d a2168-048500aMechanistic insights into the pathways of phenol hydrogenation on Pd nanostructures0 aMechanistic insights into the pathways of phenol hydrogenation o cOCT a17126-171360 v73 a

Product selectivity in aqueous phase phenol hydrogenation on well-defined supported Pd nanostructures (spheres, cubes, and octahedra) was studied using defined experiments and density functional theory (DFT) simulations. On Pd spheres and octahedra, the reaction initially showed high selectivity (in the first 3 h, at 363 K and 5 bar H-2 pressure) toward the partially hydrogenated product cyclohexanone. On prolonged operation (>20 h of reaction time), a shift in the product selectivity (up to 100%) toward the completely hydrogenated product cyclohexanol was observed on Pd spheres and octahedra. In contrast, the reaction on Pd cubes, which only had {100} facets, showed a high selectivity (similar to 90%) toward the product cyclohexanone even after 40 h, at the same reaction conditions. Since the {111} facets are expected to be the majority sites on a spherical particle, we attribute the selectivity trend observed on spherical Pd particles to be primarily controlled by the selectivity trend on the Pd{111} facets. This observation was further confirmed on performing the hydrogenation reaction on a mixture of Pd cube and Pd octahedron particles in a ratio of 25:75 (representing the site ratio of a spherical particle). DFT simulations provided a mechanistic insight into the reactivity of the two different facets ({100} and {111}) toward phenol hydrogenation. The calculations revealed that the selectivity significantly depended on the activation barriers involved in cyclohexanone hydrogenation on the Pd{111} facets (77 and 57 kJ/mol) as compared to those on the Pd{100} facets (97 and 101 kJ/mol).

10aCyclohexanol10acyclohexanone10afacet-dependent reactivity10aphenol hydrogenation1 aPorwa, Govind1 aGupta, Shelaka1 aSreedhala, S.1 aElizabeth, Joes1 aIthan, Tuhin, Suvra1 aHaider, Ali1 aVinod, C., P. uhttp://library.ncl.res.in/content/mechanistic-insights-pathways-phenol-hydrogenation-pd-nanostructures02514nas a2200301 4500008004100000022001400041245012200055210006900177260000800246300001200254490000700266520151500273653002101788653002401809653001901833653002301852100001801875700001901893700002201912700001601934700001501950700002701965700003301992700001802025700002302043700002502066856012102091 2022 eng d a0935-964800aMorphology-tuned Pt3Ge accelerates water dissociation to industrial-standard hydrogen production over a wide pH range0 aMorphologytuned Pt3Ge accelerates water dissociation to industri cJUL a22022940 v343 a

The discovery of novel materials for industrial-standard hydrogen production is the present need considering the global energy infrastructure. A novel electrocatalyst, Pt3Ge, which is engineered with a desired crystallographic facet (202), accelerates hydrogen production by water electrolysis, and records industrially desired operational stability compared to the commercial catalyst platinum is introduced. Pt3Ge-(202) exhibits low overpotential of 21.7 mV (24.6 mV for Pt/C) and 92 mV for 10 and 200 mA cm(-2) current density, respectively in 0.5 m H2SO4. It also exhibits remarkable stability of 15 000 accelerated degradation tests cycles (5000 for Pt/C) and exceptional durability of 500 h (@10 mA cm(-2)) in acidic media. Pt3Ge-(202) also displays low overpotential of 96 mV for 10 mA cm(-2) current density in the alkaline medium, rationalizing its hydrogen production ability over a wide pH range required commercial operations. Long-term durability (>75 h in alkaline media) with the industrial level current density (>500 mA cm(-2)) has been demonstrated by utilizing the electrochemical flow reactor. The driving force behind this stupendous performance of Pt3Ge-(202) has been envisaged by mapping the reaction mechanism, active sites, and charge-transfer kinetics via controlled electrochemical experiments, ex situ X-ray photoelectron spectroscopy, in situ infrared spectroscopy, and in situ X-ray absorption spectroscopy further corroborated by first principles calculations.

10aElectrochemistry10ahydrogen production10aintermetallics10awater electrolysis1 aMondal, Soumi1 aSarkar, Shreya1 aBagchi, Debabrata1 aDas, Tisita1 aDas, Risov1 aSingh, Ashutosh, Kumar1 aPrasanna, Ponnappa, Kechanda1 aVinod, C., P.1 aChakraborty, Sudip1 aPeter, Sebastian, C. uhttp://library.ncl.res.in/content/morphology-tuned-pt3ge-accelerates-water-dissociation-industrial-standard-hydrogen01803nas a2200205 4500008004100000022001400041245009700055210006900152260000800221300001400229490000700243520108500250100002701335700002501362700002201387700002101409700001801430700002501448856012401473 2023 eng d a0897-475600aMetal deficiency tailored by the 18-electron rule stabilizes metal-based inorganic compounds0 aMetal deficiency tailored by the 18electron rule stabilizes meta cJUL a6050-60580 v353 a

The 18-electron (18-e(-)) rule is typicallyrestrictedto predicting the stability of transition-metal-based complexes. Herein,we report the use of the 18-e(-) to predict the stabilityin a family of intermetallics MNiSn (M = V, Cr, Fe, and Co) crystallizingin the Co1.75Ge structure type. Site deficiencies at theM site obtained from single-crystal X-ray diffraction are understoodas attaining a stable noble gas electronic configuration. The densityfunctional theory -based structure calculation confirms that the deficientstructure is more stable than the ideal occupation available at thecrystal lattice. MnNiSn, which crystallizes in the half-Heusler crystalstructure, depicts the role of covalent radii of the constituent elementsin determining the crystal structure. Using X-ray absorption spectroscopyand X-ray photoelectron spectroscopy, the local structure of the above-mentionedcompounds was also elucidated, supporting the role of deficiency tunedvalence fluctuation to attain a 18-e(-) configurationthat eventually leads to the formation of stable compounds.

1 aSingh, Ashutosh, Kumar1 aMumbaraddi, Dundappa1 aMishra, Vidyanshu1 aRoy, Soumyabrata1 aVinod, C., P.1 aPeter, Sebastian, C. uhttp://library.ncl.res.in/content/metal-deficiency-tailored-18-electron-rule-stabilizes-metal-based-inorganic-compounds01888nas a2200181 4500008004100000022001400041245011200055210006900167260000800236300001600244490000800260520123600268100001801504700001701522700002301539700001801562856012601580 2023 eng d a1932-744700aMorphology-dependent catalysis by Co3O4 nanostructures in atmospheric pressure carbon dioxide hydrogenation0 aMorphologydependent catalysis by Co3O4 nanostructures in atmosph cJUL a13055-130640 v1273 a

In this work, three Co3O4 nanostructureswith different morphologies (cubes, rods, and sheets) were synthesizedusing a hydrothermal method and tested for the CO2 hydrogenationreaction. The physicochemical properties of the structured Co3O4 were well characterized by X-ray diffraction(XRD), Raman spectroscopy, field-emission scanning electron microscopy(FESEM), transmission electron microscopy (TEM), high-resolution transmissionelectron microscopy (HRTEM), hydrogen temperature-programmed reduction(H-2-TPR), and X-ray photoelectron spectroscopy (XPS) techniques.Based on the characterization, cube, rod, and sheet Co3O4 nanostructures were found to expose the (100), (110),and (112) planes, respectively. The effect of cobalt oxide morphologieswith different exposed surfaces on the activity and selectivity towardCO(2) hydrogenation reaction in a plug-flow reactor operatedbetween 200 and 400 & DEG;C under atmospheric pressure conditionswas explored. The results establish a correlation of the catalyticactivity with morphological structures in the order rods > sheets> cubes. H-2-TPR and XPS studies demonstrated that thehighreducibility of Co3O4 rod makes it an excellentcatalyst for CO2 hydrogenation.

1 aGupta, Sharad1 aJain, Preeti1 aJagadeesan, Dinesh1 aVinod, C., P. uhttp://library.ncl.res.in/content/morphology-dependent-catalysis-co3o4-nanostructures-atmospheric-pressure-carbon-dioxide