I used sol-gel method of TiO2 P25 for removal of VOCs, SOx, and NOx. The treatment efficiency is >90% after 30-60 min. For electrochemical method, you can check the paper below:
Article Photoelectrochemical properties of TiO2 photocatalyst and it...
No doubt, Sol-gel can be the best option here. It is simple, cost-effective and easy to carry out even by a new researcher. For more understanding about your quires please read the following articles:
"Synthesis and Photocatalytic Activity for TiO2 Nanoparticles as Air Purification"
"Preparation of a TiO2-coated photocatalytic air filter for use with an electrostatic air filter pack for xylene removal"