@article { ISI:000354255400032, title = {SBA-15-oxynitrides as a solid-base catalyst: effect of nitridation temperature on catalytic activity}, journal = {Angewandte Chemie-International Edition}, volume = {54}, number = {20}, year = {2015}, month = {MAY}, pages = {5985-5989}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

Solid bases, such as SBA-15-oxynitrides, have attracted considerable interest for potential applications as catalysts in important industrial processes. Reported herein is that by simply tuning the temperature of nitridation (ammonolysis), the catalytic activity of these solid bases can be enhanced. Solid-state NMR spectroscopy and XPS studies provided the reasoning behind this change in activity.

}, keywords = {heterogeneous catalysis, Nanostructures, NMR spectroscopy, photoelectron spectroscopy, solid-state structures}, issn = {1433-7851}, doi = {10.1002/anie.201501015}, author = {Singh, Baljeet and Mote, Kaustubh R. and Gopinath, Chinnakonda S. and Madhu, Perunthiruthy K. and Polshettiwar, Vivek} } @article {43825, title = {Amphi-functional mesoporous silica nanoparticles for dye separation}, journal = {Journal of Materials Chemistry A}, volume = {5}, year = {2017}, month = {JUL}, pages = {14914-14921}, type = {Article}, abstract = {Synthesis of amphi-functional mesoporous silica nanoparticles (similar to 80 nm) by stepwise chemical modifications of outer and inner pore surfaces is reported. These materials display a clear "Janus" like character and are able to selectively and completely separate hydrophobic dyes form a mixture of dyes. Our results clearly suggest a clear partition of more hydrophobic dyes into the pores from a mixture of two dyes. In addition this material displays a remarkable recycling ability for 10 cycles with up to similar to 99\% dye removal from water.}, doi = {10.1039/c7ta03904b}, author = {Shinde, Pravin and Sen Gupta, Sayam and Singh, Baljeet and Polshettiwar, Vivek and Prasad, Bhagavatula L. V.} } @article {47319, title = {Boron nitride and oxide supported on dendritic fibrous nanosilica for catalytic oxidative dehydrogenation of propane}, journal = {ACS Sustainable Chemistry \& Engineering}, volume = {8}, year = {2020}, month = {NOV }, pages = {16124-16135}, type = {Article}, abstract = {

In this work, we were able to significantly increase the activity of boron nitride (BN) catalysts used for the oxidative dehydrogenation (ODH) of propane by designing and synthesizing BN supported on dendritic fibrous nanosilica (DFNS). DFNS/BN showed a markedly increased catalytic efficiency, accompanied by exceptional stability and selectivity. Textural characterization, together with solid-state nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopic analyses, indicates the presence of a combination of unique fibrous morphology of DFNS and various boron sites connected to silica to be the reason for this increase in the catalytic performance. Notably, DFNS/B2O3 also showed catalytic activity, although with more moderate selectivity compared to that of DFNS/BN. Solid-state NMR spectra indicate that the higher selectivity of DFNS/BN might stem from a larger amount of hydrogen-bonded hydroxyl groups attached to B atoms. This study indicates that both boron nitride and oxide are active catalysts and by using high surface area support (DFNS), conversion from propane to propene as well as productivity of olefins was significantly increased.

}, keywords = {Electron microscopy, heterogeneous catalysis, Nanostructures, NMR spectroscopy, propane dehydrogenation, X-ray diffraction, X-ray photoelectron spectroscopy}, issn = {2168-0485}, doi = {10.1021/acssuschemeng.0c04148}, author = {Belgamwar, Rajesh and Rankin, Andrew G. M. and Maity, Ayan and Mishra, Amit Kumar and Gomez, Jennifer S. and Trebosc, Julien and Vinod, Chathakudath P. and Lafon, Olivier and Polshettiwar, Vivek} } @article {46702, title = {Photocatalytic hydrogen generation and CO2 conversion using g-C3N4 decorated dendritic fibrous nanosilica: role of interfaces between silica and g-C3N4}, journal = {ACS Applied Energy Materials}, volume = {3}, year = {2020}, month = {SEP }, pages = {8150-8158}, type = {Article}, abstract = {

We have synthesized g-C3N4 decorated over dendritic fibrous nanosilica (DFNS). The generation of C-N-Si interfaces by coating each fiber of DFNS with g-C3N4 not only provided high surface area but also affected the optical and electronic properties of the composite. The catalyst synthesis reproducibility issue of g-C3N4 was resolved using a vacuum-sealed quartz tube. The extended light absorption in the visible region, enhanced lifetime of photogenerated charge carriers due to the formation of interfaces between silica and g-C3N4 (confirmed by solid-state NMR), and increased surface area result in the improved photocatalytic activity of DFNS/g-C(3)N(4)for hydrogen generation and CO2 conversion.

}, keywords = {CO2 conversion, DFNS, g-C3N4, Hydrogen generation, nanocatalysts, photocatalysts, Solid-state NMR}, issn = {2574-0962}, doi = {10.1021/acsaem.0c01265}, author = {Rawool, Sushma A. and Samanta, Anupam and Ajithkumar, T. G. and Kar, Yusuf and Polshettiwar, Vivek} } @article {47406, title = {Lithium silicate nanosheets with excellent capture capacity and kinetics with unprecedented stability for high-temperature CO2 capture}, journal = {Chemical Science}, volume = {12}, year = {2021}, month = {APR }, pages = {4825-4835}, type = {Article}, abstract = {

An excessive amount of CO2 is the leading cause of climate change, and hence, its reduction in the Earth{\textquoteright}s atmosphere is critical to stop further degradation of the environment. Although a large body of work has been carried out for post-combustion low-temperature CO2 capture, there are very few high temperature pre-combustion CO2 capture processes. Lithium silicate (Li4SiO4), one of the best known high-temperature CO2 capture sorbents, has two main challenges, moderate capture kinetics and poor sorbent stability. In this work, we have designed and synthesized lithium silicate nanosheets (LSNs), which showed high CO2 capture capacity (35.3 wt\% CO2 capture using 60\% CO2 feed gas, close to the theoretical value) with ultra-fast kinetics and enhanced stability at 650 degrees C. Due to the nanosheet morphology of the LSNs, they provided a good external surface for CO2 adsorption at every Li-site, yielding excellent CO2 capture capacity. The nanosheet morphology of the LSNs allowed efficient CO2 diffusion to ensure reaction with the entire sheet as well as providing extremely fast CO2 capture kinetics (0.22 g g(-1) min(-1)). Conventional lithium silicates are known to rapidly lose their capture capacity and kinetics within the first few cycles due to thick carbonate shell formation and also due to the sintering of sorbent particles; however, the LSNs were stable for at least 200 cycles without any loss in their capture capacity or kinetics. The LSNs neither formed a carbonate shell nor underwent sintering, allowing efficient adsorption-desorption cycling. We also proposed a new mechanism, a mixed-phase model, to explain the unique CO2 capture behavior of the LSNs, using detailed (i) kinetics experiments for both adsorption and desorption steps, (ii) in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy measurements, (iii) depth-profiling X-ray photoelectron spectroscopy (XPS) of the sorbent after CO2 capture and (iv) theoretical investigation through systematic electronic structure calculations within the framework of density functional theory (DFT) formalism.

}, issn = {2041-6520}, doi = {10.1039/d0sc06843h}, author = {Belgamwar, Rajesh and Maity, Ayan and Das, Tisita and Chakraborty, Sudip and Vinod, Chathakudath P. and Polshettiwar, Vivek} }