Hydrogen evolution under visible light over the heterojunction p‐CuO/n‐ZnO prepared by impregnation method. (3rd September 2015)

• Record Type: Journal Article
• Authors: Belhadi, Akila; Nadjem, Imen; Zaidat, Sabrina; Boudjemaa, A.; Trari, Mohamed
• Is Part Of: International journal of energy research. Volume 39:Number 14(2015:Nov.)
• Page Start: 1909
• Page End: 1916
• Publication Date: 2015-09-03
• Subjects: Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Power resources -- Research -- Periodicals; 621.042
• DOI: 10.1002/er.3386
• Languages: English
• ISSNs: 0363-907X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The semiconducting properties of the heterojunction CuO/ZnO, synthesized by impregnation method from nitrates, are studied for the first time to assess its feasibility for the hydrogen production under visible light, an issue of energy concern. CuO exhibits a direct optical transition at 1.33 eV, due to Cu²⁺: 3<italic>d</italic> orbital splitting in octahedral site, and possesses a chemical stability in the pH range (4–14). The Mott–Schottky plot in (Na₂SO₄, 0.1 M) medium indicates <italic>p</italic>‐type conduction with a flat band potential of 0.70 V_SCE and a holes density of 1.35 × 10¹⁷ cm⁻³. As application, hydrogen evolution upon visible light is demonstrated on the heterojunction ×%CuO/ZnO (<italic>x</italic> = 5, 10 and 20 wt.%). The best performance occurs at pH ~12 with an evolution rate of 4.8 cm³ min⁻¹ (g catalyst)⁻¹ and a quantum yield of 0.12%. The improved activity is attributed to the potential of the conduction band of CuO (−1.34 V_SCE), more negative than that of ZnO, the latter acts as electrons bridge to water molecules. The presence of SO₃²⁻ reduces the recombination process, thus resulting in more H₂ evolution. Copyright © 2015 John Wiley &amp; Sons, Ltd.</p> </abstract>