A new pathway for formic acid electro-oxidation: The electro-chemically decomposed hydrogen as a reaction intermediate

Traces of hydrogen were detected during FAOR for the first time as the reaction intermediate. Inspired by this, a new but reasonable mechanism is proposed and named the hydrogen oxidation pathway. Formic acid electro-oxidation reaction (FAOR) is generally believed that follows a two-pathway mechanism. Herein, we resorted to in situ electrochemical mass spectrometry and successfully captured the trace of H 2 , as the new intermediate species, during the process of FAOR on both Pt based catalyst and two single atom catalysts (Rh-N-C and Ir-N-C). Inspired by this, we proposed a new reaction path named hydrogen oxidation pathway: at the oxidation potential, formic acid will break the C–H bond and combine with the protons in the solution to form H 2 species, then hydrogen oxidation reaction (HOR) will occur to generate two protons. This process is accompanied by electron transfer and contributes currently to the whole reaction.