Efficient Electrosynthesis of AgIISO4: A Powerful Oxidizer and Narrow Band Gap Semiconductor. Issue 35 (15th November 2016)

• Record Type: Journal Article
• Authors: Połczyński, Piotr; Gilewski, Tomasz E.; Gawraczyński, Jakub; Derzsi, Mariana; Leszczyński, Piotr Jerzy; Gadomski, Wojciech; Mazej, Zoran; Jurczakowski, Rafał; Grochala, Wojciech
• Is Part Of: European journal of inorganic chemistry. Issue 35(2016)
• Page Start: 5401
• Page End: 5404
• Publication Date: 2016-11-15
• Subjects: Silver -- Electrosynthesis -- Semiconductors -- Oxidation -- Density functional calculations; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201601183
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : A novel and efficient method for the synthesis of antiferromagnetic silver(II) sulfate, Ag II SO4, on a 20 g scale on the basis of electrosynthesis at highly anodic potentials of Ag I HSO4 solutions in 96 % sulfuric acid is reported. The product does not form at the electrode surface but rather precipitates from a saturated solution of Ag(HSO4 )2 in H2 SO4, and compact crystallites up to 250 µm in length are formed. The yield of electrolysis reaches 75 %. The remaining H2 SO4 that wets the crystals of AgSO4 is rinsed off by using anhydrous HF to yield a dry product free from crystalline or amorphous impurities, unlike previous synthetic methods. Impedance spectroscopy measurements indicate that AgSO4 is a narrow band gap semiconductor with an activation energy for conductivity of about 1.0 eV at –50 °C, which is comparable to that of elemental silicon. Theoretical hybrid density functional theory calculations corroborate this result, which yield a 0.90–0.97 eV (indirect–direct) band gap at the Fermi level (at 0 K). Abstract : Silver(II) sulfate is synthesized on a 20 g scale by using electrosynthesis and avoiding fluorinated precursors; a product of excellent crystallinity is obtained in up to 75 % yield. As shown by impedance spectroscopy and confirmed by theoretical calculations, bulk Ag II SO4 is a narrow band gap semiconductor with a fundamental band gap comparable to that of silicon (≈1.0 eV at –50 °C).