▎ 摘　　要

NOVELTY - Electrochemical detection of cadmium and lead based on sulfur-doped graphene comprises adding sodium nitrate and high purity flake graphite into concentrated sulfuric acid, stirring, slowly adding potassium permanganate, placing in the oil bath, cooling, filtering, freezing, drying to obtain graphite oxide powder, taking graphite oxide obtained, dissolving in deionized water to obtain suspension, adding sodium sulfide into deionized water to form sodium sulfide aqueous solution, adding sulfur powder, refluxing, taking obtained solution, washing and preparing of sulfur-doped graphene electrode. USE - The method is useful for electrochemical detection of cadmium and lead based on sulfur-doped graphene (claimed). DETAILED DESCRIPTION - Electrochemical detection of cadmium and lead based on sulfur-doped graphene comprises polysulfide/graphene-nafion modified working electrode, polysulfide/grapheme-nafion modified working electrode, Ag/AgCl reference electrode, Pt wire counter electrode, electrolytic cell and an electrochemical working station, (a) adding 1 g sodium nitrate and 2 g high purity flake graphite into the 46 ml concentrated sulfuric acid, under the condition of ice bath and stirring, slowly adding 6 g potassium permanganate under ice-water bath at 0 degrees C, placing in the oil bath, stirring at 35 degrees C for 30 minutes, slowly adding 88 ml de-ionized water, controlling the solution temperature at 98 degrees C, stirring for 15 minutes in an oil bath, under the stirring state, adding 10 ml hydrogen peroxide solution 30% and cooling to the room temperature, filtering the mixture, washing, freezing and drying to obtain graphite oxide powder, (b) taking 80 mg graphite oxide obtained, dissolving in 40 ml deionized water to obtain 2 mg/ml suspension, ultrasonic stirring for dispersing for 50 minutes, adjusting the pH value to 7-8 by using 1 mol/l potassium hydroxide solution, (c) adding 0.385 g sodium sulfide into 7 ml deionized water to form sodium sulfide aqueous solution, adding 0.1536 g sulfur powder, ultrasonic stirring until the solution becomes clear and transparent, under the protection of nitrogen, adding the obtained transparent solution, ultrasonic dispersing oxidized graphene suspension, refluxing for 24 hours at 80 degrees C, taking the obtained solution through filtering, washing, carrying out ultrasonic dispersion in 80 ml water, under the protection of nitrogen, adding 0.7 ml hydrazine hydrate, refluxing at 80 degrees C for 24 hours, washing the obtained product, drying at 110 degrees C for 12 hours to obtain sulfur-doped graphene composite material, (d) preparing of sulfur-doped graphene electrode by bare electrode by bare electrodes were polished with 1.0, 0.3 and 0.05 mu m aluminum oxide powders, ultrasonic cleaning using ethanol and de-ionized water for 3 minutes, using nitrogen gas for drying the electrode surface of water, taking the 1.5 mg obtained sulfur-doped graphene composite material dispersing in isopropanol and water in a volume ratio of 4:1, ultrasonically processing for time 30 minutes to obtain 1.5 mg/ml suspension, adding 4 mu l suspension drop on pyrolytic graphite electrode surface, after the lower room temperature naturally drying to obtain sulfur doped graphene electrode, (f) sulfur-doped graphene electrode measuring cadmium sulfur doped graphene electrode, silver/silver chloride reference electrode, platinum wires are respectively connected on the electrochemical working station to one end of the electrode of the sulfur doped graphene electrode, silver/silver chloride reference electrode, a platinum wire are placed in the electrolytic cell to the other end of the electrode, adding 0.1M 4 in the electrolytic cell (10 ml), HAc-NaAc solution pH value is 4.5, adding 50 mu l cadmium ion and Pb2 + solution, using the timing current method, parameter setting, an accumulation potential -1.2 V enrichment time is 240 seconds, stirring at a speed of 400 revolutions/minute, allowing to stand for 10 seconds, differential pulse anodic stripping voltammetry parameter setting starting potential - 1.0V, terminating potential including -0.4V, cadmium ions, Pb2 +, dissolution peak position are respectively -0.82V and -0.58V, recording the concentration of Cd2 +, Pb2 +, where the dissolution peak current intensity, current cleaning timing, parameter setting including cleaning potential 0.6 V, cleaning for 60 seconds, after cleaning, continuously adding Cd2 +, Pb2 + concentration, recording lower peak current intensity of different concentration are circularly measuring according to the peak current intensity and concentration drawing electrochemical analysis of lead and cadmium working curve.