▎ 摘　　要

NOVELTY - The preparation method of composite membrane electrode involves dispersing 500-1000 mg nano-bismuth oxide in 200-500 ml ethanol for 1 hour, adding 1-2 ml ammonium sulfate to the mixture and then centrifuging to obtain ammonium sulfate-modified nano-bismuth oxide, weighing graphene oxide and then stirring to obtain graphene oxide aqueous suspension, adding 10 ml graphene oxide aqueous suspension to 100 ml ammonium sulfate-modified nano-bismuth oxide and then centrifuging, ultrasonically dispersing in 10% or 500 mu l Nafion (RTM: Sulfonated tetrafluoroethylene-based fluoropolymer-copolymer) and then processing using ethanol, nitric acid, deionized water and alpha -aluminum oxide powder, washing using deionized water and drying. USE - The method is useful for preparation of composite membrane electrode, which is useful for detecting lead ions and cadmium ions. ADVANTAGE - The method enables preparation of composite membrane electrode with high sensitivity.