Graphene-based Micro/Nanocomposite Electrode Materials And Their Application In Electrochemical Sensors

Graphene based micro/nanocomposites as electrochemical sensors using novel electrodes modified materials own high electron transfer ability,high adsorption ability,high sensitivity and lower cost.Graphene based nanostructures are very significant to construct the fast response,good repeat ability and high stability electrochemical sensors.Hydrazine hydrate,hydrazine hydrate derivatives,hydroquinone and sodium borohydride have brought great harm to people and environment,although they as the reducing agents were used to effectively restore the graphene oxide?GO?.Therefore,developing the novel low-cost,high efficient and environment-friendly reducing agents are development tendency of the synthesis of reduced graphene oxide?RGO?via oxidation-reduction method.Meanwhile,the correlation studies of graphene based micro/nanostructure constructing electrochemical sensor are still at an initial stage.Especially,the researches about constructing,mechanism,properties characterization and application of novel nanostructures?such as nanowires,nanoribbons and so on?–graphene composite modified electrode are relatively few,it should be further developed and investigated.For this purpose,herein,we developed two simple approaches for chemical reduction of GO using novel reducing agents.Then,we mixed this graphene with three micro/nano structure and construct three novel electrochemical sensors.Moreover,we discuss the reducing mechanism of GO by reducing agents and the interaction mechanism between composite modified electrodes and detection molecules.At last,we investigated the electrochemical properties of modified electrodes for obtainment high adsorption ability,high selectivity,high sensibility and low cost electrochemical sensing electrode materials.Dipotassium hydrogen phosphate?K₂HPO₄·3H₂O?and sodium acetate trihydrate?NaAc·3H₂O?,which are inexpensive,environmentally friendly,and easy separation,as novel reducing agents reduce the GO in aqueous solution.The results of structural characterization of products show that the synthesized materials are single-layer or double-layer,and more importantly,these reducing agents could effectively deoxygenate the oxygen-containing functional groups and restore hexagonal honeycomb lattice of monolayer graphite.An electrochemical sensor based on in situ synthesized Cu₂ O microparticles–Cu₂O nanowires–graphene?Cu₂O MPs–Cu₂O NWs–graphene?composite for sensitive detection of ethylenediamine?EDA?is reported.The electrochemical behaviors of EDA at the Cu₂OMPs–Cu₂O NWs–graphene composite modified electrode were investigated by electrochemical impedance spectroscopy,cyclic voltammetry and linear sweep voltammetry.The electrochemical sensor exhibited excellent analytical performance for EDA detection with low detection limit of 3.83×10-5 M?S/N = 3?and a reproducibility of 1.1 % relative standard deviation.The modified electrode exhibited a rapid response to EDA within 5 s and the amperometric signal showed a good linear correlation to EDA concentration in a broad range from 0.25 to 1.25 mM with a correlation coefficient of R = 0.99699.The superior electrochemical performances of Cu₂ O MPs–Cu₂O NWs–graphene composite are attributed to their peculiar composite structure and the synergistic effects between Cu₂ O MPs,Cu₂ O NWs,and graphene.A novel electrochemical sensing platform was constructed based on ultrasonic mechanically mixing procedure prepared laminar MoO₃·2H₂O–graphene composite.As a model molecule,thiourea was utilized to investigate the electrochemical behaviors of the MoO₃·2H₂O–graphene composite modified glass carbon electrode.The results show that the composite modified electrode has higher electron transfer rate than that of graphene modified electrode and bare glass carbon electrode meanwhile the voltammetric current of it has a good linear relationship with thiourea concentration in the range of 2.40×10-3–19.27×10-3M?R =0.99814?with detection limit of 4.99 ?M?S/N = 3?.This novel electrochemical sensor exhibits a higher absorption capacity?3.87×10-8 mol/cm2?,a good reproducibility?1.41 %relative standard deviation?,excellent anti-interference and a high stability.These excellent electrochemical properties of the MoO₃·2H₂O–graphene composite are attributed to the loose and porous structure and the synergistic effects between graphene and MoO₃·2H₂O,which make this composite materials holding great potential applications for electrochemical sensor.A new Co₃O₄ porous nanoribbons-reduced graphene oxide?Co₃O₄ PNRs–graphene?nanostructure was successfully prepared by hydrothermal synthesis of Co₃O₄ porous nanoribbons and hybridizing with reduced graphene oxide.The electrochemical properties of the Co₃O₄ PNRs–graphene modified electrode were investigated by the cyclic voltammograms and amperometric current-time method.The modified electrode shows high electrochemical activity for the catalytic reduction and detection of H₂O2 in alkaline medium.The non-enzymatic hydrogen peroxide sensor exhibits wide linear range of 1–18.5 mM?R =0.99439?,high adsorption amount about 3.24×10-6 mol/cm2,and a low detection limit of5.35×10-7M?S/N = 3?.In addition,the sensor has a fast response?< 5 s?,good long-term stability,excellent repeatability?3.22 % relative standard deviation?,and high selectivity.These outstanding properties of the sensor derive from their particular hybrid structure andsynergistic effects between RGO and Co₃O₄.