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Title: Design of Atomic Ordering in Mo 2 Nb 2 C 3 T x MXenes for Hydrogen Evolution Electrocatalysis
Award ID(s):
2124478 2124241
PAR ID:
10436773
Author(s) / Creator(s):
; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Nano Letters
Volume:
23
Issue:
3
ISSN:
1530-6984
Page Range / eLocation ID:
931 to 938
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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  1. Abstract

    Synthesizing solids in molten fluxes enables the rapid diffusion of soluble species at temperatures lower than in solid‐state reactions, leading to crystal formation of kinetically stable compounds. In this study, we demonstrate the effectiveness of mixed hydroxide and halide fluxes in synthesizing complex Sr/Ag/Se in mixed LiOH/LiCl. We have accessed a series of two‐dimensional Sr(Ag1−xLix)2Se2layered phases. With increased LiOH/LiCl ratio or reaction temperature, Li partially substituted Ag to form solid solutions of Sr(Ag1−xLix)2Se2withxup to 0.45. In addition, a new type of intergrowth compound [Sr3Se2][(Ag1−xLix)2Se2] was synthesized upon further reaction of Sr(Ag1−xLix)2Se2with SrSe. Both Sr(Ag1−xLix)2Se2and [Sr3Se2][(Ag1−xLix)2Se2] exhibit a direct band gap, which increases with increasing Li substitution (x). Therefore, the band gap of Sr(Ag1−xLix)2Se2can be precisely tuned via fine‐tuningxthat is controlled by only the flux ratio and temperature.

     
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  2. Abstract

    Synthesizing solids in molten fluxes enables the rapid diffusion of soluble species at temperatures lower than in solid‐state reactions, leading to crystal formation of kinetically stable compounds. In this study, we demonstrate the effectiveness of mixed hydroxide and halide fluxes in synthesizing complex Sr/Ag/Se in mixed LiOH/LiCl. We have accessed a series of two‐dimensional Sr(Ag1−xLix)2Se2layered phases. With increased LiOH/LiCl ratio or reaction temperature, Li partially substituted Ag to form solid solutions of Sr(Ag1−xLix)2Se2withxup to 0.45. In addition, a new type of intergrowth compound [Sr3Se2][(Ag1−xLix)2Se2] was synthesized upon further reaction of Sr(Ag1−xLix)2Se2with SrSe. Both Sr(Ag1−xLix)2Se2and [Sr3Se2][(Ag1−xLix)2Se2] exhibit a direct band gap, which increases with increasing Li substitution (x). Therefore, the band gap of Sr(Ag1−xLix)2Se2can be precisely tuned via fine‐tuningxthat is controlled by only the flux ratio and temperature.

     
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  3. null (Ed.)
    Studies of the coordination chemistry between the diphenylamide ligand, NPh 2 , and the smaller rare-earth Ln III ions, Ln = Y, Dy, and Er, led to the structural characterization by single-crystal X-ray diffraction crystallography of both solvated and unsolvated complexes, namely, tris(diphenylamido-κ N )bis(tetrahydrofuran-κ O )yttrium(III), Y(NPh 2 ) 3 (THF) 2 or [Y(C 12 H 10 N) 3 (C 4 H 8 O) 2 ], 1-Y , and the erbium(III) (Er), 1-Er , analogue, and bis[μ-1κ N :2(η 6 )-diphenylamido]bis[bis(diphenylamido-κ N )yttrium(III)], [(Ph 2 N) 2 Y(μ-NPh 2 )] 2 or [Y 2 (C 12 H 10 N) 6 ], 2-Y , and the dysprosium(III) (Dy), 2-Dy , analogue. The THF ligands of 1-Er are modeled with disorder across two positions with occupancies of 0.627 (12):0.323 (12) and 0.633 (7):0.367 (7). Also structurally characterized was the tetrametallic Er III bridging oxide hydrolysis product, bis(μ-diphenylamido-κ 2 N : N )bis[μ-1κ N :2(η 6 )-diphenylamido]tetrakis(diphenylamido-κ N )di-μ 3 -oxido-tetraerbium(III) benzene disolvate, {[(Ph 2 N)Er(μ-NPh 2 )] 4 (μ-O) 2 }·(C 6 H 6 ) 2 or [Er 4 (C 12 H 10 N) 8 O 2 ]·2C 6 H 6 , 3-Er . The 3-Er structure was refined as a three-component twin with occupancies 0.7375:0.2010:0.0615. 
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