Zinc cobalt spinel

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The zinc-cobalt spinel , also Zinkkobaltspinell, Zinkkobaltit or Zinkcobaltit, Zinkdicobalttetroxid or zinc cobalt (III) oxide called, is a compound of divalent zinc and trivalent cobalt with the empirical formula ZnCo 2 O 4 . This mixed oxide is very closely related to the cobalt (II, III) oxide Co 3 O 4 : like this, it has the cubic spinel structure with the space group Fd 3 m (space group no. 227) and forms a mixed crystal row with it . Template: room group / 227

presentation

ZnCo 2 O 4 is produced in the annealing of zinc and cobalt salts ( carbonates , nitrates , oxides or hydroxides ) in a stoichiometric ratio (2 Co: 1 Zn).

Formation of zinc cobalt spinel during the annealing of zinc nitrate and cobalt (II) nitrate . Co (II) is oxidized to Co (III) by the nitrate.

Since Co 2+ can be oxidized to Co 3+ when heated in air , it is irrelevant for production in air whether divalent or trivalent cobalt salts are used:

Formation of zinc cobalt spinel when zinc carbonate and cobalt (II) carbonate are annealed in air

For synthesis can, for. For example, the mixed salt Zn y Co 2 − y (OH) 3 NO 3 can be precipitated from aqueous solution , which is then converted into spinel at 350–450 ° C in air, or a mixture of 1 mol Zn (NO 3 ) 2 · 6 H 2 O and 2 moles of Co (NO 3 ) 2 · 6 H 2 O heated to 800-850 ° C. If the amount of cobalt is too small, the ZnO · CoO mixed oxide Rinman's green is formed instead of the spinel , while larger amounts of cobalt produce mixed oxides of Co 3 O 4 and ZnCo 2 O 4 , Zn x Co 3 − x O 4 .

properties

The spinel ZnCo 2 O 4 is dark green to black. It can be p- or n-semiconducting depending on the manufacturing conditions (especially depending on the oxygen partial pressure). Like Co 3 O 4 , ZnCo 2 O 4 is  unstable above 900 ° C, releases oxygen and breaks down into ZnO, CoO or mixed oxides thereof. Zinc cobalt spinel is insoluble in sodium hydroxide solution and in warm concentrated hydrochloric acid. The powder is not noticeably attracted to a magnet.

As of the beginning of 2016, zinc cobaltite has no major applications, but possible uses in dark green pigments, as anode material in lithium-ion batteries , as a catalyst or cocatalyst or as an electrode material, e.g. B. in photoelectrochemical cells.

Historical

The later Nobel Prize winner Giulio Natta discovered zinc cobalt spinel together with M. Strada and determined its structure. They received the spinel as a “hard, deep green, almost black mass” and recognized that it is isomorphic with Co 3 O 4 . Later, while searching for an improved preparation of methanol from CO and H 2 , Natta carried out many experiments with mixed oxides of the zinc oxide ZnO as a catalyst, including zinc cobalt spinel. In the work "Cobaltite Modification of Rinman Green" published in 1932, it is said that there are "two different types of Rinman green", the common one with divalent cobalt and the "modification", the spinel with trivalent cobalt. This misleading description of two different substances as “Rinman green” later led to the incorrect statement that Rinman's green was generally the spinel ZnCo 2 O 4 .

Individual evidence

  1. ^ Crystal Structure of Co 3 O 4 . In: crystallography-online.com. Retrieved January 30, 2016.
  2. ↑ Crystal Structure of ZnCo 2 O 4 . In: crystallography-online.com. Retrieved January 30, 2016.
  3. ↑ a b c K. Krezhov, P. Konstantinov: On the cationic distribution in zinc-cobalt oxide spinels . In: Journal of Physics: Condensed Matter . tape 5 , no. 50 , 1993, pp. 9287 , doi : 10.1088 / 0953-8984 / 5/50/010 .
  4. ↑ a b c d Sven Holgersson, Aldo Karlsson: About some new cobaltites of the spinel type . In: Journal of Inorganic and General Chemistry . tape 183 , no. 1 , 1929, p. 384–394 , doi : 10.1002 / zaac.19291830128 ( online [PDF; accessed January 30, 2016]).
  5. ↑ Hyun Jung Kim et al .: Growth and characterization of spinel-type magnetic semiconductor ZnCo 2 O 4 by reactive magnetron sputtering . In: physica status solidi (b) . tape 241 , no. 7 , 2004, p. 1553-1556 , doi : 10.1002 / pssb.200304656 .
  6. ↑ Cuikun Lin, Yinyan Li, Min Yu, Piaoping Yang, Jun Lin: A Facile Synthesis and Characterization of Monodisperse Spherical Pigment Particles with a Core / Shell Structure . In: Advanced Functional Materials . tape 17 , no. 9 , 2007, p. 1459-1465 , doi : 10.1002 / adfm.200600775 .
  7. ↑ Bin Liu et al. a .: Hierarchical Three-Dimensional ZnCo 2 O 4 Nanowire Arrays / Carbon Cloth Anodes for a Novel Class of High-Performance Flexible Lithium-Ion Batteries . In: Nano Letters . tape 12 , no. 6 , 2012, p. 3005–3011 , doi : 10.1021 / nl300794f ( PDF [accessed January 30, 2016]).
  8. ↑ Sibo Wang Yidong Hou, XinChen Wang: Development of a Stable MnCo 2 O 4 Cocatalyst for Photocatalytic CO 2 Reduction with Visible Light . In: ACS Applied Materials & Interfaces . tape 7 , no. 7 , 2015, p. 4327-4335 , doi : 10.1021 / am508766s .
  9. ↑ Shannon M. McCullough, Cory J. Flynn, Candy C. Mercado, Arthur J. Nozik, James F. Cahoon: Compositionally-tunable mechanochemical synthesis of Zn x Co 3-x O 4 nanoparticles for mesoporous p-type photocathodes . In: Journal of Materials Chemistry A . tape 3 , no. 44 , 2015, p. 21990-21994 , doi : 10.1039 / C5TA07491F .
  10. ^ A b Giulio Natta , M. Strada: Spinelli del cobalto trivalente: cobaltito cobaltoso e cobaltito di zinco . In: Rendiconti della Reale Accademia Nazionale dei Lincei Series 6 . tape 7 . Rome June 1928, p. 1024-1030 ( pdf online [accessed January 30, 2016]).
  11. ^ Giulio Natta: Synthesis of Methanol . In: PH Emmett (Ed.): Catalysis . Reinhold Corp., New York 1955, pp. 349–411 ( PDF [accessed January 30, 2016]).
  12. ↑ J. Arvid Hedvall, days Nilsson: The way in which the cobaltite modification of Rinman green forms . In: Journal of Inorganic and General Chemistry . tape 205 , no. 4 , 1932, pp. 425-428 , doi : 10.1002 / zaac.19322050410 .