122nd General Meeting of the KCS

Type Poster Presentation
Area Material Chemistry
Room No. Grand Ballroom
Time 10월 18일 (목요일) 11:00~12:30
Code MAT.P-335
Subject Orthorhombic NiSe2 Nanocrystals on Si Nanowires for Efficient Photoelectrochemical Water Splitting
Authors SuYoung Lee, Jeunghee Park1,*, Eunhee Cha2, SooA Lim3
Deapartment Green Energy Engineering, Hoseo University, Korea
1Department of Materials Chemistry, Korea University, Korea
2Department of Pharmaceutics, Hoseo University, Korea
3Hoseo University, Korea
Abstract Photocatalytic water splitting is a vital technology for clean renewable energy. Despite enormous progress, the search for earth-abundant photocatalysts with long-term stability and high catalytic activity is still an important issue. We report three possible polymorphs of nickel selenide (orthorhombic phase NiSe2, cubic phase NiSe2, and hexagonal phase NiSe) as bifunctional catalysts for water-splitting photoelectrochemical (PEC) cells. Photocathodes or photoanodes were fabricated by depositing the nickel selenide nanocrystals onto p- or n-type Si nanowire arrays. Detailed structure analysis reveals that compared to the other two types, the orthorhombic NiSe2 nanocrystals are more metallic and form less surface oxides. As a result, the orthorhombic NiSe2 nanocrystals significantly enhanced the performance of water-splitting PEC cells by increasing the photocurrents and shifting the onset potentials. The high photocurrent is ascribed to the excellent catalytic activity toward water splitting, resulting in a low charge transfer resistance. The onset potential shift can be determined by the shift of the flat-band potential. A large band bending occurs at the electrolyte interface, so that photoelectrons or photoholes are efficiently generated to accelerate the photocatalytic reaction at the active sites of orthorhombic NiSe2. The remarkable bifunctional photocatalytic activity of orthorhombic NiSe2 promises efficient PEC water-splitting.
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