The Effect Of Carbonaceous Debris On The Electrochemical Behavior Of Graphene Oxide Modified Electrodes

Graphene oxide(GO)is a graphene derivative containing many highly oxidized polyaromatic carboxylated fragments.Over the past decades,different models for the structure of graphene oxide have been proposed.It has recently been reported that GO prepared via a modified Hummers method is actually composed of graphene-like sheets and low-molecular-weight highly oxidized fragments,which are named carbonaceous debris.These components are commonly separated by the base-washing method.The existence of carbonaceous debris has quite dramatic effects on the electrochemistry properties of GO,such as electrochemical properties.We focused on the effect of carbonaceous debris on the electrochemical behaviors of graphene oxide modified electrodes,including the following contents:(1)Graphene oxide(a-GO)was prepared by the modified Hummers method,and the carbon fragments from the surface were removed by base washing(b-GO).Then the reduced GO(a-RGO and b-RGO)were prepared by electrochemical reduction.Ascorbic acid(AA)and dopamine(DA)are electroactive compounds with the very similar electrochemical properties and there have an overlapping oxidation potential at an unmodified electrode,resulting in difficulty in identification.A-RGO and b-RGO were used as electrode materials to construct electrochemical sensors.We explored the effect of the fragments in the reduced graphene oxide on the simultaneous determination of DA and AA.It was found that AA and DA can be well separated when there is debris in the reduced graphene oxide,which has higher sensitivity,wider linear range and lower detection limit.(2)A-GO and b-GO were used as the base materials,chemical reduction route with chloroauric acid and sodium borohydride was followed to prepare Au/a-GO and Au/b-GO nanocomposites.The modified electrodes with two materials had a catalytic effect on hydrogen peroxide,but the Au/a-GO was obviously better than Au/b-GO.Moreover,the gold nanoparticles in Au/a-GO had smaller size and more uniformly distribution,but in Au/b-GO were assembly.Therefore,we constructed glucose biosensor with glucose oxidase(GOD)immobilised on the surface of the electrodes(named as GOD/Au/a-GO and GOD/Au/b-GO).It is found that the GOD/Au/a-GO glucose biosensor exhibited a higher sensitivity,lower detection limit and better stability than GOD/Au/b-GO.