The electrochemical measurements were performed by a PGSTAT 302N Autolab potentiostat/galvanostat analyzer (Eco-Chemie, Utrecht, The Netherlands). All test conditions were monitored by General Purpose Electrochemical System (GPES) software. A three-part DropSens SPE (DRP-110, Metrohm DropSens, Oviedo, Spain) included a graphite working electrode, a silver pseudo-reference electrode, and a graphite auxiliary electrode. The solution pH values were measured by a Metrohm 710 pH meter. X-ray diffraction analyses were performed with a Thermo Scientific device (ARL EQUINOX 3000, (Thermo, Waltham, MA, USA)). FE-SEM images were obtained using a Hitachi Model S-3700N (Hitachi, Tokyo, Japan). The TEM images were obtained using a Phillips EM 2085 machine (Philips, Amsterdam, The Netherlands).
All reagents possessed analytical grade and were from Merck (Darmstadt, Germany). Orthophosphoric acid and related salts were utilized to prepare all buffer solutions at the pH values (2.0 to 9.0).
All reagents possessed analytical grade and were from Merck (Darmstadt, Germany). Orthophosphoric acid and related salts were utilized to prepare all buffer solutions at the pH values (2.0 to 9.0).