@article { ISI:000328099400036, title = {Chemically stable multilayered covalent organic nanosheets from covalent organic frameworks via mechanical delamination}, journal = {Journal of the American Chemical Society}, volume = {135}, number = {47}, year = {2013}, month = {NOV}, pages = {17853-17861}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A series of five thermally and chemically stable functionalized covalent organic frameworks (COFs), namely, TpPa-NO2, TpPa-F-4, TpBD-(NO2)(2), TpBD-Me-2, and TpBD-(OMe)(2) were synthesized by employing the solvothermal aldehyde-amine Schiff base condensation reaction. In order to complete the series, previously reported TpPa-1, TpPa-2, and TpBD have also been synthesized, and altogether, eight COFs were fully characterized through powder X-ray diffraction (PXRD), Fourier transform IR (FT-IR) spectroscopy, C-13 solid-state NMR spectroscopy, and thermogravimetric analysis. These COFs are crystalline, permanently porous, and stable in boiling water, acid (9 N HCl), and base (3 N NaOH). The. synthesized COFs (all eight) were successfully delaminated using a simple, safe, and environmentally friendly mechanical grinding route to transform into covalent organic nanosheets (CONs) and were well characterized via transmission electron microscopy and atomic force microscopy. Further PXRD and FT-IR analyses confirm that these CONs retain their structural integrity throughout the delamination process and also remain stable in aqueous, acidic, and basic media like the parent COFs. These exfoliated CONs have graphene-like layered morphology (delaminated layers), unlike the COFs from which they were synthesized.

}, issn = {0002-7863}, doi = {10.1021/ja408121p}, author = {Chandra, Suman and Kandambeth, Sharath and Biswal, Bishnu P. and Lukose, Binit and Kunjir, Shrikant M. and Chaudhary, Minakshi V. and BabaRao, Ravichandar and Heine, Thomas and Banerjee, Rahul} } @article { ISI:000335720200011, title = {Phosphoric acid loaded azo (-N=N-) based covalent organic framework for proton conduction}, journal = {Journal of the American Chemical Society}, volume = {136}, number = {18}, year = {2014}, month = {MAY}, pages = {6570-6573}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Two new chemically stable functional crystalline covalent organic frameworkds (COFs) (Tp-Azo and Tp-Stb) were synthesized using the Schiff base reaction between triformylphloroglucinol (Tp) and 4,4{\textquoteright}-azodianiline (Azo) or 4,4{\textquoteright}-diaminostilbene (Stb), respectively. Both COFs show the expected keto-enamine form, and high stability toward boiling water, strong acidic, and basic media. H3PO4 doping in Tp-Azo leads to immobilization of the acid within the porous framework, which facilitates proton conduction in both the hydrous (sigma = 9.9 X 10(-4) S cm(-1)) and anhydrous state (sigma = 6.7 X 10(-5) S cm-1). This report constitutes the first emergence of COFs as proton conducting materials.

}, issn = {0002-7863}, doi = {10.1021/ja502212v}, author = {Chandra, Suman and Kundu, Tanay and Kandambeth, Sharath and BabaRao, Ravichandar and Marathe, Yogesh N. and Kunjir, Shrikant M. and Banerjee, Rahul} } @article {48193, title = {Doped 2D VX2 (X = S, Se, Te) monolayers as electrocatalysts for ammonia production: a DFT based study}, journal = {Applied Surface Science}, volume = {602}, year = {2022}, month = {NOV}, pages = {154401}, type = {Article}, abstract = {

Electrocatalytic nitrogen fixation under ambient conditions on vanadium dichalcogenides (VX2) with non-metal dopants has been explored herein. Understanding the interface chemistry, inherent electronic and acute synergistic nature of non-metal dopants on two unique phases of VX2 has been meticulously explored through a scrutiny of several non-metal atoms as catalytic centers. The efficacity of N-2 chemisorption and N-N bond activation has been implemented as crucial parameters to realize boron and carbon doped VX2 monolayers to be electrocatalytically active for nitrogen reduction reaction (NRR). Detailed investigation on the NRR mechanism brings out the pivotal role of thermodynamic favourability for product formation obtained from Gibbs free energy differences. The charge transfer on N and pi-pi* orbital hybridization and electron {\textquoteleft}{\textquoteleft}donor-acceptor {\textquoteleft}{\textquoteleft} mechanism between the non-metal and N-2 has been found to modulate the electrocatalytic barrier for NRR on VX2 monolayers. This study proposes boron doped VS2 as an efficient chemically feasible, earth abundant sustainable electrocatalyst for NRR with an overpotential as low as 0.06 eV.

}, keywords = {1T and 2H phases, DFT, electrocatalysts, Nitrogen Reduction Reaction, Non metal dopants, Vanadium dichalcogenides}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2022.154401}, author = {Maibam, Ashakiran and BabaRao, Ravichandar and Krishnamurty, Sailaj A.} } @article {48198, title = {High-alkaline water-splitting activity of mesoporous 3D heterostructures: an amorphous-shell@crystalline-core nano-assembly of Co-Ni-phosphate ultrathin-nanosheets and V- doped cobalt-nitride nanowires}, journal = {Advanced Science}, volume = {9}, year = {2022}, month = {AUG}, pages = {2201311}, type = {Article}, abstract = {

Introducing amorphous and ultrathin nanosheets of transition bimetal phosphate arrays that are highly active in the oxygen evolution reaction (OER) as shells over an electronically modulated crystalline core with low hydrogen absorption energy for an excellent hydrogen evolution reaction (HER) can boost the sluggish kinetics of the OER and HER in alkaline electrolytes. Therefore, in this study, ultrathin and amorphous cobalt-nickel-phosphate (CoNiPOx) nanosheet arrays are deposited over vanadium (V)-doped cobalt-nitride (V-3\%-Co4N) crystalline core nanowires to obtain amorphous-shell@crystalline-core mesoporous 3D-heterostructures (CoNiPOx@V-Co4N/NF) as bifunctional electrocatalysts. The optimized electrocatalyst shows extremely low HER and OER overpotentials of 53 and 270 mV at 10 mA cm(-2), respectively. The CoNiPOx@V-3\%-Co4N/NF (+/-) electrolyzer utilizing the electrocatalyst as both anode and cathode demonstrates remarkable overall water-splitting activity, requiring a cell potential of only 1.52 V at 10 mA cm(-2), 30 mV lower than that of the RuO2/NF (+)/20\%-Pt/C/NF (-) electrolyzer. Such impressive bifunctional activities can be attributed to abundant active sites, adjusted electronic structure, lower charge-transfer resistance, enhanced electrochemically active surface area (ECSA), and surface- and volume-confined electrocatalysis resulting from the synergistic effects of the crystalline V-3\%-Co4N core and amorphous CoNiPOx shells boosting water splitting in alkaline media.

}, keywords = {core-shell, hydrogen productions, metal nitrides, metal phosphates, synergistic effect, water-splitting}, doi = {10.1002/advs.202201311}, author = {Singh, Thangjam Ibomcha and Maibam, Ashakiran and Cha, Dun Chan and Yoo, Sunghoon and BabaRao, Ravichandar and Lee, Sang Uck and Lee, Seunghyun} } @article {48327, title = {Electrocatalytic nitrogen reduction on defective graphene modulated from single atom catalyst to aluminium clusters}, journal = {Applied Surface Science}, volume = {623}, year = {2023}, month = {JUN }, pages = {157024}, type = {Article}, abstract = {

Density Functional Theory (DFT) investigation on the most earth-abundant Al-based catalysts, has been conducted detailing its electronic properties and catalytic efficacy for nitrogen reduction at ambient condition. The Al-based catalysts have been modulated to perform as par a highly performing, but rare, Ru-single atom catalytic center by varying number of Al atoms, shape, and size. The coalesce of band-center, work function and electronic properties in metal atom catalysts along with N-N bond activation has been demonstrated to be responsible for an efficient nitrogen reduction reaction (NRR) with Delta Gmax of 0.78 eV in Al5 supported on N-doped double vacancy graphene (Al5@N4-DVG) catalyst. Electron localization function analysis has shown a weak physisorption of N2 in the Al-based catalysts. Projected Density of States (PDOS) illustrates the enhancement of aluminium electron density in Al5@N4-DVG led to enhanced orbital densities overlap of Alp and Np electrons. The Bader charge analysis and electronic analysis of the intermediates show efficient electron gain on the N atoms, leading to formation of NH3 from the NxHy intermediates in Al5@N4-DVG catalyst.

}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2023.157024}, author = {Maibam, Ashakiran and Krishnamurty, Sailaja and BabaRao, Ravichandar} }