thallium is produced in solution using a photoelectrochemical cell which has an externally electrically interconnected semiconductor photoelectrode and counter electrode . a conductive solution containing thallium is placed in the cell and a flow of current generated by exposing the photoelectrode to actinic radiation , thereby oxidizing the thallium . in another embodiment , a thallium solution is produced by mixing a solution containing thallium with a particulate semiconductor , introducing an oxygen - containing gas into the mixture , and exposing the mixture to actinic radiation . the produced thallium can be reacted with organic compounds , for example with compounds containing at least one carbon - carbon double bond to form epoxides , concurrently reducing thallium . continuous production can be obtained by recycling the reduced thallium by photoelectrochemical oxidation to thallium .