Titanium Anode Conductivity And Catalytic Mechanism Introduction
The concentration of the coating solution is proportional to the amount of coating, and the enhanced life will increase as the concentration of the coating solution increases and the amount of coating increases. But the strengthening life of the coating per unit mass is not proportional to the amount of coating. When the coating solution concentration is 0.79mo1/L, the strengthening life of the coating per unit mass is the longest. From the study of the coating structure, it is known that the addition of the intermediate layer Ir02 helps to increase the enhanced life of the electrode. The catalytic performance of the electrode is mainly affected by the surface layer of the coating, and the surface structure of the coating is greatly affected by the internal structure. The titanium substrate is treated by a combination of tortoise chemical pore making and acid etching to prepare porous electrodes. The results show that: making holes increases the real surface of the titanium substrate, increases the amount of coating per unit area, increases the electrode life, and decreases the chlorine evolution potential.
Product Introduction
Conductive Mechanism of Metal Oxide Electrodes
Electrical conductivity is one of the most fundamental properties required for an electrode.
According to the electronic structure theory described by John B. Goodenough, in TiO₂ the Ti⁴⁺ and O²⁻ orbitals hybridize to form δ and π bonds. The valence electrons completely fill the low-energy δ and π bands, while the higher-energy conduction band remains empty. From a band theory perspective, such a structure corresponds to an insulator, with a wide band gap (~3.05 eV), making pure TiO₂ poorly conductive.
To improve conductivity, TiO₂ must be doped with elements that introduce additional valence electrons. These extra electrons can:
Occupy donor energy levels near the conduction band, or
Act as charge carriers under excitation
RuO₂ Doping Mechanism
RuO₂ is a transition metal oxide with a rutile crystal structure. The outer electron configuration of Ru is 4d⁷5s¹. When Ru forms RuO₂, four electrons are transferred to oxygen atoms, completing their octet configuration, while the remaining electrons contribute to metallic conductivity.
In the RuO₂–TiO₂ solid solution:
An additional electron-containing energy band (e⁴δ) forms.
The activation energy required to excite electrons into the conduction band decreases to approximately 0.2 eV.
The effective band gap narrows dramatically from ~3.05 eV to ~0.2 eV.
This transforms TiO₂ from an insulator into an n-type semiconductor with excellent electrical conductivity.
Additional factors enhancing conductivity:
RuO₂ is typically oxygen-deficient, increasing free electron concentration.
During coating processes, partial substitution of oxygen by chlorine further increases unpaired electrons.
Thus, embedding RuO₂ into TiO₂ (or vice versa) creates a highly conductive mixed oxide electrode system.
Comparison with Ta and Nb Doping
Doping TiO₂ with 1 mol%:
Ta increases conductivity by ~4160 times
Nb increases conductivity by ~5500 times
Since Ru provides four free electrons per atom-more than Ta or Nb-the RuO₂–TiO₂ solid solution exhibits superior conductivity.
Technical Summary
Metal oxide electrodes achieve:
High conductivity through donor doping and band-gap narrowing
High catalytic activity via reversible valence state transitions
Efficient chlorine evolution due to oxygen-deficient defect structures
Excellent stability in chlor-alkali and electrochemical environments
This combination makes titanium-based noble metal oxide electrodes ideal for:
Chlor-alkali industry
Electrolytic sodium hypochlorite generation
Wastewater electro-oxidation
Seawater electrolysis
Electrochemical synthesis systems
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