An iodine-treated metal-organic framework with enhanced catalytic activity for oxygen reduction reaction in alkaline electrolyte

Abstract Herein, a zeolite-like metal-organic framework (MOF, i.e., ZIF-67) is treated with I2 at 170 °C and without any solvents and inert atmospheres to obtain the oxygen reduction reaction (ORR) catalysts (i.e., I2&ZIF-67). After treated with I2, the ORR activity of I2&ZIF-67 in alkaline electrolyte has been significantly increased compared with the pristine ZIF-67. Particularly, the optimized I2&ZIF-67(2:1) shows the half-wave potential of ∼0.83 V and Tafel slope of ∼37.3 mV per current decade, which is comparable to 20 wt% Pt/C. The enhanced ORR activity is mainly attributed to the generation of active pyridinic-N, Co2+ and I3− species induced by the interaction between I2 and ZIF-67. Moreover, the I2 treatment also facilitates the charge and mass transfer for ORR. This work provides a strategy to develop highly efficient ORR catalysts derived from MOFs at low temperature.