Nanoporous TiO2 electrode grown by laser ablation of titanium in air at atmospheric pressure and room temperature

• TiO2 films via laser ablation of Ti in air under standard temperature and pressure conditions
• Nanoporous crystalline structure from one-step process
• Anatase content > 70% in the mixed phase film

Recently, fabrication of the nanoporous TiO2 photoelectrode on metal foils by means of sputtering of the Ti film on preheated metal substrate followed by the TiO2 deposition (doctor blade technique) and sintering represents the frequently applied technique. This is despite the relatively complicated procedure and number of parameters to be controlled in order to fabricate films of required properties. In this work an approach is applied and discussed in which the nanoporous TiO2 electrode is fabricated under conditions similar to pulsed laser deposition but with the deposit formed directly on the ablated target at atmospheric pressure and room temperature. The titanium dioxide thin film is grown by ablation of the Ti foil with the nanosecond UV laser (266 nm) at fluence up to 1.5 J/cm2. The rutile–anatase phase transformation takes place during this one-step process and no thermal pre-and post-treatment of the deposit is needed. In samples produced in air, the presence of mixed phases of the non-stoichiometric anatase (> 70%), rutile and negligible amount of TiN is consistently confirmed by the X-ray diffraction, energy-dispersive X-ray and Raman spectra. For applications of the reported films as electrode material in the third generation photovoltaic cells, the use of industrial lasers could significantly improve the process efficiency.