Using first-principles calculations,hydrogen evolution reaction(HER)activity on two-dimensional(2D)gallium chalcogenides monolayers GaX(X=O,S,Se,and Te)as well as the derived Janus monolayers Ga2XY(X≠Y,X/Y=O,S,Se,and Te)were systematically examined.It was found that Ga2OSe Janus monolayer with a 0.3％strain has the lowest AGH*of 0.19 eV(modified to-0.01 eV including the solvation effect)because(ⅰ)O is the most electronegative among X/Y atoms,(ⅱ)the Ga2OSe monolayer has a larger lattice parameter with respect to GaO monolayer,and(ⅲ)the built-in electric field is enhanced after H adsorption.The enhanced H adsorption with the lattice stretching is a result of the weaker Ga-O bond strength before H adsorption and the reduced electron fillings of anti-bonding molecular orbital formed by H 1s and O 2pz orbitals after H adsorption.The O-pz band center can be served as a descriptor to describe the HER activity trend for these p-block materials.Moreover,Ga2OSe monolayer has appropriate band alignment,distinguished optical absorption coefficient(105 cm-1),low exciton binding energy(0.71 eV),and the spontaneous HER process,indicating that it is a highly potential candidate for near-infrared photocatalyst for hydrogen production.Our research provides a novel paradigm that forming Janus structure can effectively tune the HER activity,which would guide the searching for excellent HER photocatalysts for clean hydrogen production.

Yu Cui;Mengyuan Li;Xiaoli Zhang;Sufan Wang;Yucheng Huang

College of Chemistry and Material Science,Key Laboratory of Electrochemical Clean Energy of Anhui Higher Education Institutes,The Key Laboratory of Functional Molecular Solids,Ministry of Education,Anhui Laboratory of Molecule-Based Materials,Anhui Normal University,Wuhu,241000,China

绿色能源与环境（英文）

[1]Yu Cui;Mengyuan Li;Xiaoli Zhang;Sufan Wang;Yucheng Huang-.Ga2OSe monolayer:A promising hydrogen evolution photocatalyst screened from two-dimensional gallium chalcogenides and the derived janus)[J].绿色能源与环境（英文）,2022(05):1045-1052

Ga2OSe,GaX,Ga2XY,GaO,2pz

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