TiO2@G photoelectrodes sensitized with natural pigments for reduction of ammonia in aquaculture tanks with visible light

Abstract

The degradation of waste nitrogen compounds produced in aquaculture tank is commonly done through the usa of biofilters (among other methods) to avoid ecosystem poisoning. An alternative method is TiO2-based photocatalyst to degrade NH3 into N2. On the other hand, graphene is a material with a high charge transport efficiency which is proposed to enhance the photocatalyst system efficiency. In this work TiO2 and TiO2@G films were made by Pechini method onto Fluorine-doped Tin Oxide (FTO), Aluminium-doped Zinc Oxide (AZO), Stainless Steel (SS) and Soda Lime Glass (SLG) substrates. The molar ratios in the Pechini solution were 20:5:1 of titanium isopropoxide, citric acid and ethylene glycol respectively. A mixture of Pechini-TiO2pm25 nanopowder was made and ultrasonically dispersed until a paste is formed and therefore the paste was deposited on FTO and SS substrates (≈1cm2 ) by doctor blade technique and lately calcined up to 450 °C. Some of the electrodes were impregnated with the ethanolic extract of Laburnum anagyroides Medic. known as golden rain tree to sensitize it to visible light. Films were characterized by Reflectance Spectroscopy (RS), X Ray Diffraction (XRD), and current-voltage (I-V) and photodegradation activity with methylene blue. The results are discussed in terms of substrate type, graphene presence and sensitization. Financed by SIP 20151074 and CONACYT 169108