Iron(II) phthalocyanine (FePc) over carbon support for oxygen reduction reaction electrocatalysts operating in alkaline electrolyte

Abstract

In this work, we initially report a detailed advancement in the utilization of metal-N 4 chelate macrocycles in the oxygen reduction reaction (ORR). Then, iron(II) phthalocyanines supported on two different carbon-based supports specifically carbon nanotube and black pearl (carbon spheres) were synthesized and their activities toward ORR in alkaline media were studied. With the help of physical and surface characterization like Raman, BET, XRD, XPS, and electron microscopy analysis, the similarity in surface chemistry and surface area of the materials and the differences in the structure and morphology of the supports were established. This work also brings forth the effect of support properties on the electrocatalytic activity of the materials by a detailed electrochemical analysis using rotating disk electrode in oxygen saturated 0.1 M KOH. Comparison with existing literature on Fe-phthalocyanine supported on diverse carbon support is presented.

Iron-Based Electrocatalysts for Energy Conversion: Effect of Ball Milling on Oxygen Reduction Activity

“…Oliveira et al investigated ORR behaviour in an alkaline electrolyte of FeN 4 macrocycles supported over carbon nanotubes and carbon spheres via a wet impregnation strategy. Those catalysts achieved a reduction potential of 0.82 V and 0.85 V vs. RHE, with an ECSA of 45 m 2 g −1 and 57 m 2 g −1 , respectively [12]. Optimizing surface area and porosity improves the mass transport, and consequently, ORR performance [64].…”

“…In this context, many studies have been addressed to develop alternative catalysts to noble metals (i.e., platinum), which are expensive, rare and sensitive to poisoning [3,8]. Platinum-group-metal-free (PGM-free) catalysts represent a very promising category of new catalysts due to their tuneable composition based on transition metals (Fe, Ni, Co, Mn, Cu) supported on carbon substrates (graphene, graphene oxide, carbon nanotubes, black pearls, carbon black and biochar), which are also doped with heteroatoms (N, P, S, O) [12][13][14][15][16][17][18][19][20] Among PGM-free catalysts, metal-nitrogen-carbon (M-N-C) materials have been widely investigated toward ORR in acidic and alkaline pH, whereas the study of ORR in neutral media still accounts for few reports [6,8,12,21,22]. So far, attention has been paid to the development of Fe-N-C catalysts, and the efficiency of active sites in Fe-N-C composites has been ascribed to the coordination of iron to nitrogen heteroatoms in FeNx structure, which cause a beneficial effect on the direct conversion of oxygen to water via a four-electron mechanism [1,8,10,18].…”

“…Among the various iron sources for FeN-C catalysts, Iron (II) phthalocyanine (FePc) has attracted a great interest due to its low-cost, tuneable electronic property, facile methods of synthesis, and low overpotential for oxygen reduction [1,3,4,6,9,12,[25][26][27][28][29][30][31]. Dong and coworkers have shown that the poor electron conductivity and stability of phthalocyanine complexes increase when FeN 4 macrocycles are incorporated on nitrogen-functionalized carbon supports and further submitted to pyrolysis treatment [32].…”

Bimetal Phthalocyanine‐Modified Carbon Nanotube‐Based Bifunctional Catalysts for Zinc‐Air Batteries

“…Several reports on the ORR performance on nanocarbons doped with single transition metal and nitrogen derived from MN 4 macrocycles (e. g. MPcs) can be found in literature. [28,37,65] However, due to the lack of literature available on bifunctional catalysts prepared by transition metal macrocycles and carbon supports, it is challenging to compare the results herein. Recently, cobalt phthalocyanine derived CDC/CNT catalyst was reported indicating that the decrease in the CDC/CNT ratio increased the ORR performance with the best catalyst exhibiting E onset of 0.91 V. [37] Niu and co-workers have prepared N, P, S codoped carbon nanosheets decorated with NiCoP nanoparticles as bifunctional catalyst (NiCoP/NSP-HPCNS), reporting the E 1/2 value of 0.84 V in 0.1 M KOH due to the highly active sites in hierarchical porous structure.…”

“…[13][14][15][16][17][18][19][20][21][22][23][24] Among numerous non-precious metal catalysts, it has been established that the transition metal and nitrogen co-doped nanocarbon (MÀ NÀ C) catalysts are promising candidates for ORR due to the synergetic effects of metal and nitrogen in addition to the graphitic and porous structure of carbon. [25][26][27][28][29][30] For OER, transition metal oxides are good replacement for state-of-the-art IrO 2 and RuO 2 catalysts. [31] Further, these type of catalysts are economically favourable due to their low cost and earth-abundant precursors.…”