Kwon, Ik Seon Kwak, In Hye Debela, Tekalign Terfa Abbas, Hafiz Ghulam Park, Yun Chang Ahn, Jae-pyoung Park, Jeunghee Kang, Hong Seok 2024-01-19T17:33:00Z 2024-01-19T17:33:00Z 2022-01-25 2020-05 1936-0851 https://pubs.kist.re.kr/handle/201004/118645 Two-dimensional MoSe2 has emerged as a promising electrocatalyst for the hydrogen evolution reaction (HER), although its catalytic activity needs to be further improved. Herein, we report Serich MoSe2 nanosheets synthesized using a hydrothermal reaction, displaying much enhanced HER performance at the Se/Mo ratio of 2.3. The transition from the 2H to the 1T' phase occurred as Se/Mo exceeded 2. Structural analysis revealed the presence of Se adatoms as well as the formation of Se-Se bonding. Based on first-principles calculations, we propose two equally stable Se-rich structures. In the first one, excess Se atoms bridge two MoSe2 layers via the interlayer Se-Se bonds. In the second one, the Se atoms substitute for the Mo atoms, and extra Se atoms are added closest to the Mo-substituted Se. Calculation of Gibbs free energy along the reaction path indicates that the Se adatoms of the second model are the most active sites for HER. English AMER CHEMICAL SOC Se-Rich MoSe2 Nanosheets and Their Superior Electrocatalytic Performance for Hydrogen Evolution Reaction Article 10.1021/acsnano.0c02593 1 ACS NANO, v.14, no.5, pp.6295 - 6304 ACS NANO 14 5 6295 6304 N scie scopus 000537682300112 2-s2.0-85085536731 Chemistry, Multidisciplinary Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Chemistry Science & Technology - Other Topics Materials Science Article TOTAL-ENERGY CALCULATIONS ACTIVE EDGE SITES CATALYTIC-ACTIVITY 1T PHASE EFFICIENT TRANSITION IDENTIFICATION MODULATION MONOLAYERS DEFECTS MoSe2 phase transition enriched Se first-principles calculation hydrogen evolution