Formic acid–Formate blended solution: A new fuel system with high oxidation activity

Formic acid and formate have been proven to be among the most promising fuels for direct liquid fuel cells. To take advantage of both formic acid and formate, the oxidation activity of a formic acid–formate blended solution was studied using cyclic voltammetry, Tafel polarization measurements, and chromoamperometry. With increased concentration of formate, the oxidation potential of formic acid shifted to the negative direction, and the peak current significantly increased, suggesting a greatly enhanced oxidation activity. The transition of formic acid from an indirect to a direct oxidation route was also observed. The enhanced oxidation activity indicated that a formic acid–formate blended solution is a promising fuel system for direct liquid fuel cells. Hence, a new concept of fuel cell, i.e., direct formic acid–formate blended fuel cell, was proposed.