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The direct,rapid and sensitive detection of analytes has always been a subject of close attention in the field of analytical chemistry.Electrochemical sensors have received extensive attention in the quantitative detection of various analytes due to their simple and rapid analytical capabilities,relatively inexpensive instruments,and excellent miniaturization potential.graphene-based electrodes are the most commonly used working electrodes in electrochemical sensors,which have the advantages of rich variety,low cost,high chemical stability,and wide potential window.However,unmodified graphene-based electrodes often suffer from low sensitivity and poor selectivity.Moreover,when electrodes are used to detect complex biological samples,the surface of the electrodes is highly susceptible to contamination by biological macromolecules or interference from coexisting electroactive substances,thereby reducing the sensitivity and accuracy of detection.Therefore,developing suitable graphene-based electrode modification or modification methods to effectively improve the electrode detection performance will enhance the practical application ability of graphene-based electrochemical sensors.This paper innovates three-dimensional graphene electrodes and quantum dots,and uses electrochemical methods to detect p-phenol and catechol.and the use of quantum dots as electrochemiluminescent emitters for the detection of hydrogen peroxide.The details are as follows:Three-dimensional graphene(3DG)with macroporous structure has great potential in the field of electroanalysis owing to a large active area,excellent electron mobility and good mass transfer.However,simple and low-cost preparation of 3DG electrodes with high electrocatalytic ability is still a challenge.Here,a fast and convenient electrochemical polarization method is established to pretreat free-standing 3DG(p-3DG)to offer high electrocatalytic ability.3DG with monolithic and macroporous structure prepared by chemical vapor deposition(CVD)is applied as the starting electrode.Electrochemical polarization is performed using electrochemical oxidation(anodization)at high potential(+6 V)followed with electrochemical reduction(cathodization)at low potential(-1 V),leading to exposure of edge of graphene and introduction of oxygen-containing groups.The as-prepared p-3DG displays increased hydrophilicity and improved electrocatalytic ability.As a proof of concept,p-3DG was used to selective electrochemical detection of two isomers of benzenediol,hydroquinone(p-BD)and catechol(o-BD).In comparison with initial 3DG,p-3DG exhibits increased reversibility of redox reaction,improved peak current and good potential resolution with high potential separation between p-BD and o-BD.Individual or selective determination of p-BD or o-BD in single substance solution or binary mixed solution is realized.Real analysis of pond water is also achieved.The simple green synthesis of GQDs with anodic ECL remains an important challenge.Here,we propose a nitrogen-doped GQD(N-GQD)anodic ECL sensing platform that can sensitively detect hydrogen peroxide(H2O2)and glucose.N-GQD is easily prepared using a one-step molecular fusion between a carbon precursor and a dopant in an alkaline hydrothermal process.The method is simple,green and has high yield.The prepared N-GQD exhibits monolayer graphene lamellar structure,uniform size and good crystallinity.In the presence of H2O2,N-GQD has high anodic ECL activity due to functional hydrazide groups.Using N-GQD as ECL probe,the sensitive detection of H2O2in the range of 0.3-100.0μM can be achieved.The detection limit or LOD is 63 n M.Due to the oxidation of glucose catalyzed by glucose oxidase(GOx)to produce H2O2,the sensitive detection of glucose was also achieved in the range of 0.7-90.0μM(LOD 96 nM).