Impact of Textural Properties of Mesoporous Porphyrinic Carbon Electrocatalysts on Oxygen Reduction Reaction Activity

Abstract

Transition-metal-and N-codoped carbon (MÀN/C) catalysts have shown great promise as alternatives to Pt-based catalysts in the oxygen reduction reaction (ORR). The preparation of MÀN/C catalysts by exploiting mesoporous silica templates is highly appealing as this method can generate catalysts with high surface areas, well-developed porosities, and abundant active sites. Herein, we report the relationship between the textural properties of mesoporous silica-templated FeÀN/C catalysts and their ORR activity. Iron-doped mesoporous porphyrinic carbons (FeÀMPCs) with varying textural properties were synthesized through nanocasting using mesoporous silicas as the templates and Fe porphyrin as the precursor. FeÀMPC catalysts showed excellent ORR activities with half-wave potentials reaching 0.82 V and 0.90 V (vs. reversible hydrogen electrode, RHE) in acidic and alkaline electrolytes, respectively. FeÀMPC catalysts with smaller particle sizes, larger mesopore sizes, and three dimensionally interconnected pore structures showed enhanced ORR activities.[a] J. carbon paper test, 40 mL of catalyst ink was deposited on the 1 1 cm 2 carbon paper (EC-TP-060T, Toray), resulting in a catalyst loading of 1 mg cm À2 . The measurement protocol with a carbon paper electrode was the same as that by the RRDE test. The measurements were independently repeated at least three times and the average data are presented. 4 5 6 7 8

Comparative Study of the Oxygen Reduction Reaction on Pyrolyzed FePc in Acidic and Alkaline Media

“…Transition metal macrocycle compounds, such as iron phthalocyanine (FePc), have well‐defined structure and considerable ORR activity. After the heat treatment, their catalytic activity can be further improved ,,,. Therefore, metal macrocycle compounds can serve as a good starting material for the study of active sites of pyrolyzed M/N/C catalysts.…”

Iron-decorated nitrogen-rich carbons as efficient oxygen reduction electrocatalysts for Zn–air batteries

“…26–29 To boost the electrocatalytic activity, it is essential for the catalysts to possess high density of active sites, large surface area, and desired porous structure. 19, 30–38 However, these features are generally achieved using costly organometallic compounds and hard templates, as well as tedious post treatment, compromising the economy and scalability. 2, 39–41…”

Iron/Nitrogen co-doped mesoporous carbon synthesized by an endo-templating approach as an efficient electrocatalyst for the oxygen reduction reaction

“…In order to produce an efficient electrocatalyst able to replace the commercial platinum catalyst, the following conditions have to be met, namely: i) the presence of a high density of active centers and ii) a large specific surface area with a porosity made up of fully accessible pores that facilitate the transport of the reactants and products towards and away from the active sites [13][14][15][16][17][18]. Considerable effort has been made to identify these active centers and to determine their catalytic effect on the ORR process [19][20][21].…”