Hydrogen evolution using CdWO4 modified by BiFeO3 in the presence of potassium iodide; a combination of photocatalytic and non-photocatalytic water splitting |
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| Affiliation: | 1. State Key Lab of Crystal Materials, Shandong University, Shandong, 250100, PR China;2. School of Physics, Shandong University, Shandong, 250100, PR China;1. Department of Chemistry, Fujian Normal University, Fuzhou 350007, PR China;2. Research Center of Analysis and Measurement, Zhejiang University of Technology, Hangzhou 310014, PR China;3. Hangzhou Area Military Representative Office, Hangzhou, 310011, PR China;4. Institute of Environmental Science and Engineering, Hangzhou Dianzi University, Hangzhou 310018, PR China;1. Department of Applied Physics, Chongqing University, Chongqing 400044, PR China;2. Department of Mathematics and Physics, Officer College of the Chinese People''s Armed Police Forces, Chengdu 610213, PR China;1. Shanghai Key Lab of Chemical Assessment and Sustainability, Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai, 200092, China;2. Shenyang National laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, 72 Wenhua Road, Shenyang 110016, China |
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| Abstract: | Novel heterogeneous structure of BiFeO3–CdWO4 with different molar ratios was applied for the photocatalytic hydrogen evolution in a self-designed externally UV/visible irradiated photoreactor in the presence of potassium iodide. The photocatalysts were synthesized by simple hydrothermal method and characterized by XRD, FE-SEM-mapping, TEM, UV–Vis DRS, PL, EIS, transient photocurrent and Mott-schottky techniques to identify the structural, optical and photoelectrochemical properties. The slope of Mott-schottky plots confirmed the p-type and n-type conductivity of the synthesized BiFeO3 and CdWO4, respectively. The p-n heterojunctions exhibited more efficiently light absorption, charge separation and electron mobility relative to the pure photocatalysts. We observed that coupling 40 mol% BiFeO3 with CdWO4 provided the best photocatalytic performance of hydrogen evolution, 268.90 μmol h?1.gcat?1 from distilled water and 379.43 μmol h?1.gcat?1 from 0.05 M KI aqueous solution. Iodine species increased H2 evolution efficiency because of taking part in the charge transfer processes, either by scavenging excited holes or by direct reduction of H+ to H? under UV irradiation. Fermi level equilibrium in the p-n heterojunction suggests the best interparticle charge transfer mechanism explaining how photoinduced electrons with superior energy states and desirable lifetime can be supplied to reduce H+ to H?. |
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| Keywords: | Photocatalytic hydrogen evolution Iodide ions |
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