Photoelectrocatalytic activities of porous TiO_2 film electrode coated on foam nickel substrates prepared by a hard-template method

The porous TiO2 film electrode coated foam nickel (PTFN) is prepared by a hard-template method by using activated carbon as the pore-forming agent and foam nickel as the substrate. The PTFN was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), etc., and its photoelectrocatalytic activity was evaluated by degradation of methylene blue (MB) solution. Meanwhile, the effects of anode bias voltage, ventilation rate, initial concentration of MB and amount of carbon-pore-forming agent on photoelectrocatalytic performance were investigated. The results show that PTFN has higher photoelectrocatalytic activity for the MB degradation than the non-porous TiO2 film coated foam nickel substrate, as electrode with high surface area is capable in providing high MB concentration to be degraded and therefore a faster reaction rate. Under 3 V of bias voltage, 40 L · h-1 of ventilation rate and 1 mg · L-1 of MB initial concentration with a mole ratio of activated carbon to Ti element in precursor of 10%, the photoelectrocatalytic degradation efficiency of methylene blue is the highest. Meanwhile, it is also found that MB molecules are oxidized by free radicals in the process of photoelectrocatalytic degradation and demethylated in the CN bond rupture, and finally degraded into H2O, CO2 and ions such as SO42-,NO3- and Cl-.