“…Expectedly, the Fe III -based wave is observed at the more positive potential than the W VI -based waves. Notably, the reduction of POMs can not only increase the negative charge but also can improve the basicity of the polyoxoanion, thus, the concomitant protonation may exist in the reduction process of POMs [36]. To investigate the influence of the variation of the pH value of the supporting electrolyte on the electrochemical response of 1, H 2 SO 4 was utilized to adjust the pH values of medium.…”