Preparation And Application Of Oxide Anodes With Iridium-Titanium Oxide Interlayer

Ti-substrate Ti/TiO₂-IrO_x/IrO₂ and Ti/TiO₂-IrO_x/IrO₂-SnO₂ electrodes with iridium-titanium oxide interlayer were first prepared by the impregnation-thermal decomposition method. The TiO₂-IrO_x interlayer was obtained from a mixture of TiN nano-particle and H2IrCl6 solutions. Electrochemical tests and material analyses had been used to investigate their morphological structure, electrocatalytic activity. The electrocatalytic activity and service life of Ti/TiO₂-IrO_x/IrO₂ electrode was compared with the traditional Ti/IrO₂ electrode. The electrocatalytical activity of the Ti/TiO₂-IrO_x/IrO₂-SnO₂ electrode with iridium-titanium oxide interlayer had been studied primarily for sea water flue gas desulfurization technology.In case of Ti/TiO₂-IrO_x/IrO₂ coating anode:(1) The XRD results showed that TiN had been mainly converted to TiO₂ rutile-type phase at 500℃. TiO₂ and IrO₂ formed a binary solid solution in a rutile phase, moreover, a coherent interface was formed between the interlayers and the titanium substrate.(2) The SEM results indicate that the IrO₂ layers exhibited a typical cracked and smooth layer of IrO₂, and small particles with a higher Ir content were dispersed on the mudcrack-free surface. Crack decreased with increasing the preparation temperature, which contributes to improve the service life of electrode. Crack increased and particles decreased with increasing the TiO₂ content in the interlayer, the electrocatalytical activity for oxygen evolution increased.(3) The electrocatalytical activity for oxygen evolution increased with decreasing the preparation temperature and increasing the TiO₂ content in the interlayer attained by anodic polarization curves. The Ti/TiO₂-IrO_x/IrO₂ coating anodes with n(Ir)/n(Ti) = 1.5 in TiO₂-IrO_x interlayer calcined at 450℃have similar high electrochemical activities with the traditional Ti/IrO₂ anodes, in agreement with the anodic voltammetric charge. (4) Compared with the traditional Ti/IrO₂ anodes, it may not only increase the electrocatalytic activity for oxygen evolution of the Ti/TiO₂-IrO_x/IrO₂ anode after 20 applications, but also may greatly improve the service life of the electrode.(5) Life time of the Ti/TiO₂-IrO_x/IrO₂ coating anodes with iridium-titanium oxide interlayer was superior to that of the traditional Ti/IrO₂ anodes, which increases sextuple. It is feasible using TiO₂-IrO_x as interlayer for coating anode.In case of Ti/TiO₂-IrO_x/IrO₂-SnO₂ coating anode:(1) Anodic polarization curves showed that Ti/TiO₂-IrO_x/IrO₂-SnO₂ coating has the lower electrode potential for evolution of chlorine, the higher electrode potential for evolution of oxygen, more selective in electrocatalysis. The Ir and Sn content has little effect on the electrocatalysis of the anode coating.(2) Ti/TiO₂-IrO_x/IrO₂-SnO₂ coating anode has the longer service life. The results showed that the coating with n(Ir)/n(Sn)=1:6 in active mass exhibited the highest accelerated life in 2 mol/L H₂SO₄ solution under 3A/cm², about 411h.(3) Ti/TiO₂-IrO_x/IrO₂-SnO₂ coating anode applied on sea water flue gas desulfurization exhibited high activity. With current density of 200mA/cm², pH of 3.5, the removal rate of Na₂SO₃ solution(440mg/L) was 90.9% when the electrolysis's time was 15min, and the removal rate of COD was 82.6%.The above-mentioned results reveal this kind of oxide anodes with iridium-titanium oxide interlayer is so promising that deserved further research.