Oxygen reduction reaction (ORR) in alkaline media has been attracted increasing concerns with the development of fuel cells and metal-air batteries. Ordinarily, the ORR has been recognized as a kind of multi-step electrochemical reactions, with very sluggish kinetics. For overcoming the above limiting factors, the electrocatalysts for ORR are crucial for developing a variety of renewable-energy devices. In the past two decades, the transition metal phthalocyanines (TMPcs) are widely studied as alternative ORR catalysts due to their outstanding performance along with their low price and abundant supply. Considering the type of the central transition-metal (TM) atom and catalyst supports play an important role in improving the ORR performance. In this work, a convenient method is reported to elucidating the performance of transition-metal phthalocyanine (TMPc) catalyst for the oxygen reduction reaction (ORR) catalytic mechanism by using electrochemical measurements and density functional theory (DFT) calculations. The graphitization carbon black (GCB) supported iron phthalocyanine (FePc/C), cobalt phthalocyanine (CoPc/C), nickle phthalocyanine (NiPc/C) and Copper phthalocyanine (CuPc/C) are tested in the experimental methods. We explore the correlation between the experimental results and the theoretical models for the ORR mechanisms: (i) the O2 end-on adsorption is the major step to determine the ORR onset potential; (ii) the way of O2 adsorbed on TMPc is the key point to affect the Tafel slope; (iii) the -H2O2 desorption determine the ORR transfer electron number; and (iv) the -OH desorption and the central TM atom removal leads to the damage for catalytic durability.

Oxygen reduction reaction mechanisms study for transition-metal phthalocyanine supported on graphitization carbon black

251st National Meeting (2016)

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