Preparation, characterisation and sensing application of inkjet-printed nanostructured TiO2 photoanode

Inkjet printing technique is proposed for the fabrication of titanium dioxide (TiO2) photoanodes with a synthetic colloidal TiO2 ink. The resultant electrodes were characterised using materials characterisation methods (such as scanning electron microscope, X-ray diffraction and UV–vis spectrophotometer) as well as photoelectrochemical means. The preliminary results indicate that the nanostructure of the original TiO2 particles is well maintained in the printing process, and the thickness and uniformity of the TiO2 thin film can be well controlled by the simple printing technique. Combined with photoelectrochemical means, the inkjet-printed TiO2 photoanode is capable of oxidising organic compounds in aqueous solution, including weak organic adsorbates (e.g., glucose, phenol) and strong organic adsorbates (e.g., potassium hydrogen phthalate (KHP), glutaric acid, malonic acid) indiscriminately in bulk cell. This characteristic is utilized to determine chemical oxygen demand (COD) in aqueous samples. A linear range of 0–120 mg/L of O2 and a detection limit of 1 mg/L of O2 were achieved. The photoelectrochemical activity of the printed electrodes was found to be highly reproducible. Inkjet-printing technique can be a versatile method for mass production of TiO2 photoanodes as sensors.