Study On Properties Of Titanium-based Metal Oxide Anodes Modified With Graphene

Titanium-based metal oxide anodes are prepared by coating precious metal oxide on titanium substrate, for short DSA. The Ti/IrO2Ta2O5 electrode has found good electrocatalytic activity and high stability under oxygen evolving conditions. The Ti/RuO2-IrO2-SnO2 has been used widely in seawater electrolysis. With the continuous expansion of the application fields, the anodes’ excellent electrocatalytic activity and longer life are needed. Graphene is a new nano carbon material with two-dimensional single flake structure. Graphene has a great specific surface area (2630 m2·g-1) and very high conductivity at room temperature. With its excellent properties, the application of graphene for improving titanium-based metal oxide anodes has been investigated.IrO2-Ta2O5 and RuO2-IrO2-SnO2 coated titanium anodes with different graphene contents were prepared using conventional thermal decomposition method. The improved electrochemical performance and stability were discussed. The microstructure was analyzed using FESEM, EDS and XRD, and the electrochemical properties were investigated by electrochemical testing including oxygen evolving potential(OEP), chlorine evolving potential(CEP), cyclic voltammetry(CV), anode polarization curves, electrochemical impedance spectroscopy(EIS) and accelerated life test(ALT).The influence with different graphene contents on electrochemical properties of IrO2-Ta2O5 coated titanium anodes was studied, the results indicated that the Ti/TrO2-Ta2O5-G anodes provide more active center for oxygen evolution reaction and increase electrochemically active surface area. The electrochemical properties of Ti/IrO2-Ta2O5-G anodes are improved to a different degree and the anode with 0.4 g·L-1 graphene contents presents the best electrochemical performance.The Ti/IrO2-Ta2O5-G anodes with graphene were made at 400℃-550℃. It is showed that, the coating surfaces of the anode have obvious uneven morphologies and stronger X ray diffraction peak intensity when heat treatment temperatures exceed 450℃. The average grain sizes D increase with increased temperatures. The anode sintered at 400℃ presents the best oxygen evolution electrochemical performance and then gradually decreases as temperature rises. Accelerated life are improved dramatically with the increase of temperature and decreased with the further increase, the anode sintered at 500℃ has the longest accelerated life.The electrochemical properties and accelerated electrolysis life of Ti/RuO2-IrO2-SnO2-G anode with graphene was studied. As compared with the traditional Ti/RuO2-IrO2-SnO2 anode, the Ti/RuO2-IrO2-SnO2-G anode has larger electrochemically active surface area, higher electrocatalytic activity and accelerated life. The active components on coating surface of traditional anode for electrocatalytic activity suffer heavy losses and the exposure of titanium substrate is markedly increased after 80 h accelerated life test, instead, the new-style anode does not decrease apparently and thus has a certain electrocatalytic activity still. The dissolution and falling off of active components on coating surface and the increase of nonconducting TiO2 are material cause for the deactivation of the two kinds of anode.