▎ 摘　　要

NOVELTY - Detecting soluble sulfide based on transition metal carbides and nitrides (MXene)/graphene oxide (GO)/silver iodide (AgI) three-dimensional heterojunction composite aerogel involves cutting fluorine-doped indium tin oxide (FTO) conductive glass, ultrasonicating in acetone, ethanol and water, and drying in infrared after cleaning, and covering the brown tape with round holes on surface of the FTO electrode, and forming circular groove. MXene/GO/AgI three-dimensional heterojunction composite aerogel suspension with a concentration of 2 mg/ml is taken and dropped it in the circular groove of the FTO electrode and air dried naturally, phosphate-buffered saline as an electrolyte solution is added in cell, and MXene/GO/AgI/FTO is utilized as working electrode, and the photocurrent is tested followed by dropping S2-solutions of different concentrations on surface of aerogel, air-drying naturally, drawing a standard working curve, and obtaining S2-concentration in the sample to be tested. USE - Method for detecting soluble sulfide based on transition metal carbides and nitrides (MXene)/graphene oxide (GO)/silver iodide (AgI) three-dimensional heterojunction composite aerogel. ADVANTAGE - The method utilizes the Ksp-inducing effect, that is AgI and S2-reaction is converted into silver sulfide with smaller Ksp, thus realizing the sensitive detection of soluble sulfides, and detection range of the samples to be tested of 5 nM to 0.2 mM, and the lowest detection limit of 1.54 nM. DETAILED DESCRIPTION - Detecting soluble sulfide based on transition metal carbides and nitrides (MXene)/graphene oxide (GO)/silver iodide (AgI) three-dimensional heterojunction composite aerogel involves cutting fluorine-doped indium tin oxide (FTO) conductive glass into a 1x2 cm rectangle, ultrasonicating in acetone, ethanol and water for at least 10 minutes, and drying in infrared after cleaning, and covering the brown tape with round holes on the surface of the FTO electrode, and forming a circular groove with a diameter of 1-4mm in the working area. 20 mul MXene/GO/AgI three-dimensional heterojunction composite aerogel suspension with a concentration of 2 mg/ml is taken and dropped it in the circular groove of the FTO electrode and air dried naturally, phosphate-buffered saline as an electrolyte solution is added in the electrolytic cell, and MXene/GO/AgI/FTO is utilized as the working electrode, and the photocurrent is tested under the condition of a three-electrode system and a bias voltage of 0-0.6V followed by dropping 20 mul S2-solutions of different concentrations on the surface of the MXene/GO/AgI 3D heterojunction composite aerogel, and air-drying naturally, utilizing MXene/GO/Ag2S/FTO as the working electrode, testing optical properties under the same conditions, taking the concentration of S2-solution as the abscissa, the measured photocurrent value as the ordinate, drawing a standard working curve, where the concentrations of the S2-solution are 0.001, 0.002, 0.005, 0.01, 0.05, 0.2, 1, 5, 50, 200, 500, 1000, 2000 and 3000 muM, repeating the step, dropping 20 mul sample to be tested on the surface of the MXene/GO/AgI 3D heterojunction composite aerogel, air drying naturally, utilizing MXene/GO/Ag2S/FTO as the working electrode, and testing the photocurrent under the same conditions, after comparing with the standard working curve, and obtaining S2-concentration in the sample to be tested.