%0 Journal Article
%T High-Efficiency Photochemical Water Splitting of CdZnS/CdZnSe Nanostructures
%A Chen-I Wang
%A Zusing Yang
%A Arun Prakash Periasamy
%A Huan-Tsung Chang
%J Journal of Materials
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/703985
%X We have prepared and employed TiO2/CdZnS/CdZnSe electrodes for photochemical water splitting. The TiO2/CdZnS/CdZnSe electrodes consisting of sheet-like CdZnS/CdZnSe nanostructures (8每10ˋ m in length and 5每8ˋnm in width) were prepared through chemical bath deposition on TiO2 substrates. The TiO2/CdZnS/CdZnSe electrodes have light absorption over the wavelength 400每700ˋnm and a band gap of 1.87ˋeV. Upon one sun illumination of 100ˋmWˋcmˋ2, the TiO2/CdZnS/CdZnSe electrodes provide a significant photocurrent density of 9.7ˋmAˋcmˋ2 at ˋ0.9ˋV versus a saturated calomel electrode (SCE). Incident photon-to-current conversion efficiency (IPCE) spectrum of the electrodes displays a maximum IPCE value of 80% at 500ˋnm. Moreover, the TiO2/CdZnS/CdZnSe electrodes prepared from three different batches provide a remarkable photon-to-hydrogen efficiency of 7.3ˋ㊣ˋ0.1% (the rate of the photocatalytically produced H2 by water splitting is about 172.8ˋmmol﹞hˋ1﹞gˋ1), which is the most efficient quantum-dots-based photocatalysts used in solar water splitting. 1. Introduction Developing environmentally clean energy resources from abundant solar energy has attracted considerable attention these years [1]. Hydrogen production by photochemical water splitting is a promising route because hydrogen has the highest energy density values per mass (140ˋMJˋkgˋ1) and its oxidation product (H2O) is more eco-friendly [2每4]. Hitherto, many semiconductors with band-gap energy exceeding the oxidation potential of water (1.23ˋV versus normal hydrogen electrode (NHE)) at pH 1.0 have been employed for water splitting [5]. Albeit metal oxides including TiO2, ZnO, and their derivatives are the most common photocatalysts used in water splitting, yet they provide low overall photon-to-hydrogen efficiency ( ) attributed to their wide band gaps [6, 7]. To overcome these limitations, doping other metal or inorganic ions to TiO2 and ZnO materials has been demonstrated [8]. However, this strategy is not quite successful, mainly because their band gaps are greater than 2.0ˋeV (620ˋnm) [9], whereas photocatalysts having band gaps less than 2.0ˋeV can absorb solar light in the visible to near-infrared region more efficiently. Quantum dots (QDs) such as CdTe [10], CdS [11每13], and CdSe [14每18] have been anchored to TiO2 and ZnO electrodes to harvest visible light for more efficient water splitting. Photoelectrochemical cells (PECs) incorporating QDs-sensitized TiO2 electrodes provide several advantages: (i) ease of fabrication, (ii) generation of multiple electron/hole [19], (iii) high visible light
%U http://www.hindawi.com/journals/jma/2013/703985/