Thus, 12 sets of electrodes were formed under conditions combining the pH of the electrolyte, the precipitation method and the drying temperature: at pH 1 by CV method and drying at 60 0 C (pH1_CV_60), at pH 1 by CA method and drying at 60 0 C (pH1_CA_60), at pH 1 by CV method and drying at 90 0 C (pH1_CV_90), at pH 1 by CA method and drying at 90 0 C (pH1_CA_90), at pH 2 by CV method and drying at 60 0 C (pH2_CV_60), at pH 2 by CA method and drying at 60 0 C (pH2_CA_60), at pH 2 by CV method and drying at 90 0 C (pH2_CV_90), at pH 2 by CA method and drying at 90 0 C (pH2_CA_90), at pH 3,5 by CV method and drying at 60 0 C (pH3,5_CV_60), at pH 3,5 by CA method and drying at 60 0 C (pH3,5_CA_60), at pH 3,5 by CV method and drying at 90 0 C (pH3,5_CV_90), at pH 3,5 by CA method and drying at 90 0 C (pH3,5_CA_90).