Comparatively Studies On The Surface Roughness Factor Of Polycrystalline Gold Electrode Influenced By The Different Pretreatments

Due to the surface roughness factor (RF) has an important influence on the reproducibility of the electrochemical detection and the monolayer self-assembling on polycrystalline gold electrode, therefore, the accurate determination of RF on polycrystalline gold electrodes is always a very important research subject. In this paper, we use cyclic voltammetry and potential steps combining linear sweep voltammetry technology, through oxygen adsorption and iodine adsorption methods, K3[Fe(CN)6] probe and [Ru(NH3)6]Cl3 probe methods, respectively, to obtain the RF values of polycrystalline gold electrode surfaces pretreated by different modes such as mechanical polishing (M1), piranha reagent (M?), UV/O3 (M3), and aqua regia solution (M4). The significance of the differences between those RF values are discussed from the points of view of statistic. At the same time, the influence of the changes of pH values from 0.3 to 8.3 on the RF values is given. Experimental results show that:(1) The RFo orders given by oxygen adsorption method rank, RFo (M1)= 3.14> RFo (M2)= 3.10> RFo (M3)= 2.90> RFo (M4)=1.68. The variations of pH values from 0.3 to 8.3, do not result in the remarkably differentiations of RFo values in statistical significance.(2) The RFeL orders given by potential step-linear sweep voltammetry method are, RFEL (M1)=3.34> RFEL (M2)= 3.28> RFEL (M3)= 2.89> RFEL (M4)= 1.73. The RFEL values derived from t= 5 s show no statistical differences from those RFo values.(3) The RFI orders given by iodine adsorption method list as, RFI (M2)= 1.46> RFI (M1)= 1.43> RF1 (M3)= 1.32> RF, (M4)= 0.89.(4) The RFFe orders given by potassium ferricyanide probe method array as, RFFe (M2)= 1.019> RFFe (M1)= 1.007> RFFe (M4)= 1.003> RFFe (M3)= 0.998.(5) The RFRu orders given by chloride hexammoniate ruthenium probe method gradate, RFRu (M1)= 1.045> RFRu (M2)= 1.041> RFRu(M4)= 1.036> RFRu (M3)= 1.033.(6) The RFE orders obtained at the electrochemical window from-0.8 to 1.5 V vs Ag/AgCl with the scanning speed of 100 mV/s fit in with, RFE (Mi)= 3.016> RFE (M2)= 2.908> RFE (M3)= 2.712> RFE (M4)= 1.651. Statistical analysis results show that values of RFE (M1) and RFE (M1) do not differentiate from each other distinctly, but they are quite different from those of both RFE (M3) and RFE (M4). The optimal electrochemical polishing potential window ranges from 0 to 1.5 V vs Ag/AgCl, accompanying with 30 cycles.It is concluded from above, that the differences of values among RFo (M1-M3), RFEL (M1-M3) and RFI (Mi-M3) meaningless statistically. However, they are significantly different from the corresponding values of RFo (M4), RFeL (M4), and RF1 (M4), separately. Furthermore, the differences of values between RFFe (M1-M4) and RFRu (M1-M4) show no statistical signification. As pH values variation from 0.3 to 8.3, values of both RFFe (M1-M4) and RFRu (M1-M4) change insignificantly.For the pretreatment M1-M3, the values rank in orders of RFo (M1-M3)> RFEL (M1-M3)> RFE (M1-M3)> RFi (M1-M3)> RFRu (M1-M3)> RFFe (M1-M3). Similarly, for the pretreatment M4, the values rank in orders of RFEL (M4)> RFo (M4)> RFE (M4)> RFRu (M4)> RFFe (M4)> RF1 (M4). For any kind of pretreatments concerned, the values among RFo, RFEL, and RFE; show no differences in statistical meaning. While, the same is between the values of RFFe and RFRu. But the cases are otherwise from the former group to the latter group, as well as to the values of RF1.