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Computational Chemical Journey
Use the state of the art electronic structure simulation tools and analysis to understand, design and discover materials for catalysing chemical reactions such as CO oxidation reaction (auto-mobile exhaust catalyst), methane conversion, oxygen reduction and hydrogen evolution reactions (Fuel cell), nitrogen reduction reaction (ammonia synthesis), electrochemical synthesis of hydrogen peroxide and so on, for application in renewable energy technologies aiming green environment.
We use a combination of density functional theory (DFT) calculations and experimental approaches to explore the stability and electrocatalytic activity of a wide range of transition-metal single atoms on a TiC support. Our theoretical prediction that single atoms can be stabilized on the modified TiC surface is confirmed by experimental findings using them on a TiC support. The predicted activities where Pt and Au single atoms would be the best for hydrogen evolution and selective oxygen reduction reactions, respectively, agree well with experimental results. This rational strategy using computational modeling of materials enables effective design of highly active and stable single-atom catalysts.
Using density functional theory (DFT) we have investigated the adsorption of NH3 molecule on the rutile SnO2(110) and mixed Sn0.5Ti0.5O2(110) surfaces. NH3molecule gets absorbed on the 5-coordinated Sn atom (Sn5c)of the surface in tilted mode having an additional hydrogen bond with nearby surface bridged oxygen (Obr) atom. After adsorption, 3a1molecular orbital of ammonia undergo significant dispersal as itdonates its electron to surface atoms. The adsorption energy is found to be 1.4-1.6eV. Inclusion of Ti atoms in the SnO2lattice leads to decrease in the adsorption energy value.
Single atomic Pt catalyst can offer efficient utilization of the expensive platinum and provide unique selectivity because it lacks ensemble sites. However, designing such a catalyst with high Pt loading and good durability is very challenging. Here, single atomic Pt catalyst supported on antimony‐doped tin oxide (Pt1/ATO) is synthesized by conventional incipient wetness impregnation, with up to 8 wt% Pt. The single atomic Pt structure is confirmed by high‐angle annular dark field scanning tunneling electron microscopy images and extended X‐ray absorption fine structure analysis results. Density functional theory calculations show that replacing Sb sites with Pt atoms in the bulk phase or at the surface of SbSn or ATO is energetically favorable. The Pt1/ATO shows superior activity and durability for formic acid oxidation reaction, compared to a commercial Pt/C catalyst. The single atomic Pt structure is retained even after a harsh durability test, which is performed by repeating cyclic voltammetry in the range of 0.05–1.4 V for 1800 cycles. A full cell is fabricated for direct formic acid fuel cell using the Pt1/ATO as an anode catalyst, and an order of magnitude higher cell power is obtained compared to the Pt/C.
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