ZnGa(2-x)In(x)S4 (0 ≤ x ≤ 0.4) and Zn(1-2y)(CuGa)(y)Ga(1.7)In(0.3)S4 (0.1 ≤ y ≤ 0.2): optimize visible light photocatalytic H2 evolution by fine modulation of band structures.
Inorg Chem
; 54(5): 2467-73, 2015 Mar 02.
Article
em En
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| ID: mdl-25695506
ABSTRACT
Band structure engineering is an efficient technique to develop desired semiconductor photocatalysts, which was usually carried out through isovalent or aliovalent ionic substitutions. Starting from a UV-activated catalyst ZnGa2S4, we successfully exploited good visible light photocatalysts for H2 evolution by In(3+)-to-Ga(3+) and (Cu(+)/Ga(3+))-to-Zn(2+) substitutions. First, the bandgap of ZnGa2-xInxS4 (0 ≤ x ≤ 0.4) decreased from 3.36 to 3.04 eV by lowering the conduction band position. Second, Zn1-2y(CuGa)yGa1.7In0.3S4 (y = 0.1, 0.15, 0.2) provided a further and significant red-shift of the photon absorption to â¼500 nm by raising the valence band maximum and barely losing the overpotential to water reduction. Zn0.7Cu0.15Ga1.85In0.3S4 possessed the highest H2 evolution rate under pure visible light irradiation using S(2-) and SO3(2-) as sacrificial reagents (386 µmol/h/g for the noble-metal-free sample and 629 µmol/h/g for the one loaded with 0.5 wt % Ru), while the binary hosts ZnGa2S4 and ZnIn2S4 (synthesized using the same procedure) show 0 and 27.9 µmol/h/g, respectively. The optimal apparent quantum yield reached to 7.9% at 500 nm by tuning the composition to Zn0.6Cu0.2Ga1.9In0.3S4 (loaded with 0.5 wt % Ru).
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MEDLINE
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En
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Inorg Chem
Ano de publicação:
2015
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Article