Improved Photocatalytic H 2 Evolution from Inorganic/Organic Sacrificial Solution over Ni-Doped (CuIn) 0.2 Zn 1.6 S 2 Ph
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Improved Photocatalytic H2 Evolution from Inorganic/Organic Sacrificial Solution over Ni-Doped (CuIn)0.2Zn1.6S2 Photocatalysts Xianghui Zhang, Dengwei Jing, Liejin Guo State Key Lab of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, PR China ABSTRACT The Ni-doped (CuIn)0.2Zn1.6S2 photocatalysts were prepared via a two-step ultrasonichydrothermal method under an environmental-friendly condition. XRD pattern profiles suggested that Ni2+ successfully doped into (CuIn)0.2Zn1.6S2 lattice. UV-Vis spectra indicated that the optical properties of the photocatalysts greatly depended on the amount of Ni doped. SEM images show that the samples were microspheres. The microsphere structures were gradually damaged with the increment of Ni doping amount. The photoactivity of (CuIn)0.2Zn1.6S2 was enhanced when Ni2+ was doped into the crystal structure. The H2 evolution performance over the prepared samples from inorganic/organic sacrificial solution was systematic investigated. INTRODUCTION Photocatalytic water splitting to produce H2 using solar energy over semiconductors has become one of the most promising methods to solve the problems of environmental pollutions and energy crisis of our society [1,2]. Great progress has been made in the research and application of the photocatalytic H2 productions since Fujishima and Honda first reported the photoelectronchemical water splitting in 1972 [3]. To date, many effective photocatalysts have been developed [4,5]. However, these photocatalysts only work in UV region. Thus, to develop visible-light-driven photocatalyst has become an imperative topic. In recent years, many efforts have been made to broaden the responding region of photocatalyst to visible light region. A few of visible-light-driven photocatalysts have been developed [6,7]. One effective approach to develop visible-light-driven photocatalyst is introducing an impurity state into the forbidden band or narrowing the band gap by doping a foreign element into active photocatalysts with wide band gap. Sulfides are attractive materials as candidates of visible-light-driven photocatalysts due to their narrow bang gaps and suitable conduction band level [8]. Recently, some multicomponent metal sulfides have been reported to be more stable and show higher photocatalytic activity under visible light [9,10]. The authors also synthesized (CuIn)xZn2(1-x)S2 solid solution firstly via hydrothermal method and used it as efficient photocatalysts to produce H2 under visible light [11]. Moreover, the CdxZn1-xS solid solution doped with Cu and Ni showed greatly improved photoactivity even without Pt as a cocatalyst [12,13]. This indicated that a tune band structure of photocatalyst by both solid solution and metal ion doping is an effective way to develop photocatalysts with high valence band level and narrow band gap. On the other hand, photoinduced electrons are also very easy to recombine with holes in semiconductor. This recombination will lead to the lower quantum efficiency of photocatalysis. Adding sacri
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