Chapter 6 Photocatalytic Hydrogen Production with Visible Light over Pt-Interlinked Hybrid Composites of Cubic-Phase and Hexagonal-Phase CdS
Chapter 6 Photocatalytic Hydrogen Production with Visible Light over Pt-Interlinked Hybrid Composites of Cubic-Phase and Hexagonal-Phase CdS
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发表时间：
2010
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通讯作者：
L. A. Silva;S. Ryu;J. Choi;W. Choi;M. R. Hoffmann
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作者：
L. A. Silva;S. Ryu;J. Choi;W. Choi;M. R. Hoffmann
以平均粒径为13 nm、带隙能量为2.6 eV的纳米颗粒立方相CdS （c-CdS）与带隙能量为2.3 eV的体相六方CdS （hexx -CdS）为基材，制备了一种混合相硫化镉基质的混合光催化体系。所制备的杂化纳米复合催化剂在可见光照射下从水中产生氢气方面具有光催化效率。采用c-CdS/Pt/ hexx - cds复合光催化剂，在pH为14的硫化钠和亚硫酸钠混合背景电解质体系存在下，H2产率接近1.0 mmol-H2 g h。相反，在水-异丙醇溶剂体系中，相同的复合材料在pH为7时以0.15 mmol g h的速率产生H2。合成的杂化催化剂反应活性的相对顺序为：c-CdS/Pt/ hexx - cds > Pt/c-CdS/ hexx - cds > c-CdS/hexCdS > Pt/ hexx - cds > hexx - cds >量子级c-CdS。电子空穴捕获态寿命的延长取决于水合镉的表面化学性质，包括表面羟基（>CdOH）和巯基（>CdSH）。
A hybrid photocatalytic system, which is based on a mixed-phase cadmium sulfide matrix composed of nano-particulate cubic-phase CdS (c-CdS) with average particle diameters of 13 nm and a bandgap energy of 2.6 eV, is coupled with bulk-phase hexagonal CdS (hex-CdS) that has a bandgap energy of 2.3 eV and is interlinked with elemental platinum deposits. The resulting hybrid nano-composite catalysts are photocatalytically efficient with respect to hydrogen gas production from water with visible light irradiation at > 420 nm. Rates of H2 production approaching 1.0 mmol-H2 g h are obtained with a c-CdS/Pt/hex-CdS composite photocatalyst, in the presence of a mixed sodium sulfide and sodium sulfite background electrolyte system at pH 14. In contrast, the same composite produces H2 at a rate of 0.15 mmol g h at pH 7 in a water-isopropanol solvent system. The relative order of reactivity for the synthesized hybrid catalysts was found to be: c-CdS/Pt/hex-CdS > Pt/c-CdS/hex-CdS > c-CdS/hexCdS > Pt/hex-CdS > hex-CdS > quantum-sized c-CdS. A mechanism involving enhanced lifetimes of electron-hole trapping states that are dependent on the surface chemistry of hydrated CdS involving surface hydroxyl (>CdOH) and sulfhydryl groups (>CdSH) are invoked.