Phthalocyanine precursors to construct atomically dispersed iron electrocatalysts

Carbon materials embedded with atomically dispersed metal sites have recently demonstrated intriguing performance as electrocatalysts. However, it remains challenging to construct abundant single metal atoms due to easy aggregation of metal species during the high-temperature synthesis. Herein, a facile method is devloped to construct single iron atom electrocatalysts with high iron content by employing iron phthalocyanine (FePc) derivatives as metal precursors. FePc molecules are encapsulated into the zeolitic imidazolate frameworks (ZIFs), and the subsequent pyrolysis yields the catalysts. Cyano substitution on FePc (FePc(CN)₈) can facilitate introduction of phthalocyanine molecules and formation of active sites, thus affording higher activity for the oxygen reduction reaction than the FePc counterpart. It is also found that adding iron salt with FePc(CN)₈ can afford a better catalyst with enhanced surface Fe-N_x content, which exhibits high activities with a half-wave potential of 0.910 and 0.811 V versus reversible hydrogen electrode in alkaline and acidic conditions, respectively. Moreover, FePc(CN)₈/ZIF-derived catalyst exhibits high selectivities and good activities for carbon monoxide production in the carbon dioxide reduction reaction (CO₂RR). The bulk Fe-N_x sites are found to be more stable than the surface Fe-N_x sites possibly due to the improved desorption of carbon monoxide. © 2019 American Chemical Society.