02139nas a2200253   4500008004100000022001400041245016900055210006900224260000800293300001400301490000600315520119100321653001901512653003001531653002001561653003201581653002801613100002801641700002501669700001801694700002101712700002401733856012801757       2017                        eng d  a2196-021600aNitrogen-doped graphene with a three-dimensional architecture assisted by carbon nitride tetrapods as an efficient metal-free electrocatalyst for hydrogen evolution0 aNitrogendoped graphene with a threedimensional architecture assi  cOCT  a2643-26520 v43 aCurrent polymer membrane-based electrolyzers use Pt as a cathode catalyst for efficient reduction of water. The high cost of Pt-based catalysts forces researchers to develop alternative electrocatalysts. Here, a simple strategy has been proposed to synthesize a metal-free electrocatalyst for the hydrogen evolution reaction (HER) by high-temperature annealing of graphene oxide-coated melamine foam. The prepared catalyst possesses both structural and functional advantages with its three-dimensional (3D) interconnected arms of carbon nitride (CNx) backbone wrapped with nitrogen-doped graphene (N-RGO) sheets (CNx@N-RGO). CNx@N-RGO faces only a 193 mV overpotential to achieve a current density of 10mAcm(-2), which is far superior to the previously reported Pt-free systems. Along with the high exchange current density 34.7 x 10(-6)A cm(-2) and low Tafel slope of 54 mV dec(-1), CNx@N-RGO follows a Volmer-Heyrovsky mechanism for the HER. DFT calculations show that the synergy between CNx and N-RGO facilitates good electrical coupling between the two moieties and provides optimal binding to H+ ions on the catalyst that, in turn, results in efficient reduction of hydrogen ions.10acarbon nitride10aDensity functional theory10aelectrocatalyst10ahydrogen evolution reaction10anitrogen doped graphene1 aGangadharan, Pranav, K.1 aUnni, SreeKuttan, M.1 aKumar, Nandha1 aGhosh, Prasenjit1 aKurungot, Sreekumar  uhttps://library.ncl.res.in/content/nitrogen-doped-graphene-three-dimensional-architecture-assisted-carbon-nitride-tetrapods02099nas a2200205   4500008004100000245011800041210006900159260000900228300001400237490000700251520137300258100001801631700001801649700002001667700001801687700001501705700002401720700001901744856013001763       2021                        eng d00aImproving the optical and thermoelectric properties of Cs2InAgCl6 with heavy substitutional doping: a DFT insight0 aImproving the optical and thermoelectric properties of Cs2InAgCl  cFEB   a5521-55280 v113 a<p>The next-generation indium-based lead-free halide material Cs2InAgCl6 is promising for photovoltaic applications due to its good air stability and non-toxic behavior. However, its wide bandgap (&gt;3 eV) is not suitable for the solar spectrum and hence reduces its photoelectronic efficiency for device applications. Here we report a significant bandgap reduction from 2.85 eV to 0.65 eV via substitutional doping and its effects on the optoelectronic and opto-thermoelectric properties from a first-principles study. The results predict that Sn/Pb and Ga and Cu co-doping will enhance the density of states significantly near the valence band maximum (VBM) and thus reduce the bandgap via shifting the VBM upward, while alkali metals (K/Rb) slightly increase the bandgap. A strong absorption peak near the Shockley-Queisser limit is observed in the co-doped case, while in the Sn/Pb-doped case, we notice a peak in the middle of the visible region of the solar spectrum. The nature of the bandgap is indirect with Cu-Ga/Pb/Sn doping, and a significant reduction in the bandgap, from 2.85 eV to 0.65 eV, is observed in the case of Ga-Cu co-doping. We observe a significant increase in the power factor (PF) (2.03 mW m(-1) K-2) for the n-type carrier after Pb-doping, which is similar to 3.5 times higher than in the pristine case (0.6 mW m (-1) K-2) at 500 K.</p>
1 aBhamu, K., C.1 aHaque, Enamul1 aPraveen, C., S.1 aKumar, Nandha1 aYumnam, G.1 aHossain, Md., Anwar1 aSharma, Gautam  uhttps://library.ncl.res.in/content/improving-optical-and-thermoelectric-properties-cs2inagcl6-heavy-substitutional-doping-dft