In recent years, many efforts have been devoted to the fabrication of photoelectrochemical sensors based on the catalytic activity of TiO Great attention has also been paid to the development of novel materials with electrocatalytic properties for COD sensors with amperometric detection,which unlike TiO, do not require any UV light source to activate them and thus act as electrocatalysts. Although a boron-doped diamond electrode has been reported for COD detection at +2.8 V (vs Ag/AgCl),2.18 the use of materials with catalytic properties can be more advantageous.