The Effect of Ni and Sb Oxide Precursors, and of Ni Composition, Synthesis Conditions and Operating Parameters on the Activity, Selectivity and Durability of Sb-Doped SnO₂Anodes Modified with Ni

Abstract

http://eprint.ncl.ac.uk The effect of Ni and Sb oxide precursors, and of Ni composition, synthesis conditions and operating parameters on the activity, selectivity and durability of Sb-doped SnO 2 anodes modified with Ni

Deposition efficiency in the preparation of ozone-producing nickel and antimony doped tin oxide anodes

“…This most probably leads to difficulties in controlling the resulting composition in the oxide coating which will have a negative effect on the reproducibility of the samples. The properties of antimony doped tin oxide anodes prepared in this fashion have indeed been shown to be very sensitive to the choice of temperature and duration during both drying and calcination [14,21,22]. As mentioned earlier, the optimized compositions (and maximum current efficiencies) determined for the NATO electrode coatings varies among studies.…”

“…An intriguing aspect of the material was that a very small concentration of nickel added to the mixed oxide yielded an electrode that made it possible to produce ozone at low anode potentials (2.2 V vs. Ag/AgCl) at room temperature and at relatively high current efficiencies (∼30 %) while the current efficiency was almost 0 % in the absence of nickel. Since then, several groups have studied the material and current efficiencies of up to 54 % at potentials below 3 V vs. Ag/AgCl have been reported [7,[10][11][12][13][14][15][16]. The minimum energy demand found so far is 18 kWh/kg O3 [7] which, to our knowledge, is the lowest value reported for the electrochemical formation of ozone and is moreover low enough to compete with the CCD process.…”

“…Some studies have however reported measured compositions of their oxide coatings: Cheng et al [8] determined the Sn:Sb ratio of their coating to 7:1 using ICP-MS (inductively coupled plasma -mass spectrometry), far from the composition in the prepared precursor solution of 65:1. This was later discussed to be a consequence of surface enrichment of Sb [9,14]. Other studies have also reported an enrichment of either Sb or Ni, or both [24][25][26].…”

“…The variation in current efficiencies in the above-mentioned studies can depend on a number of parameters such as number of applied layers [11,14], electrolyte type [9,11,17] and concentration [9,11], current densities and potentials [9,14], cell design [12], or calcination temperatures [14,18]. In the present study, we have focused on the importance of the Sn, Sb, and Ni precursor salts.…”

“…The actual composition of these doped tin oxide coatings has proven difficult to determine [9,13,14,18,23] using XPS (X-ray photoelectron spectroscopy) or EDX (Energy-dispersive X-ray analysis), probably due to low nickel concentrations and the overlap of the tin and antimony spectral lines. Some studies have however reported measured compositions of their oxide coatings: Cheng et al [8] determined the Sn:Sb ratio of their coating to 7:1 using ICP-MS (inductively coupled plasma -mass spectrometry), far from the composition in the prepared precursor solution of 65:1.…”