Porphyrins and phthalocyanines of various forms are capable of acting as catalysts for a wide range of chemical reactions including both oxidation and reductions. When incorporated into carbon they are of particular interest as non-precious metal catalysts for the oxygen reduction reaction (ORR) in fuel cells. A potential route to improving the properties of such ORR electrocatalysts is by including phthalocyanines into polymerization reactions that lead to hierarchically porous polymers that can be converted into very active high surface area carbons. The carbon was prepared using resorcinol and formaldehyde polymerization with the addition of the nonionic surfactant F127 and diaminohexane (DAH) as co-surfactant and the crosslinking agent. The F127 and Dah produce mesopores, and macrophase separation produces macropores within the final carbon. Copper (II) protoporphyrin IX (CuIX), copper phthalocyanine disulfonate (CuPc2S), and Alcian Blue (CuPc-8gx) were incorporated into the polymerization and resulting carbons. The stability of these compounds after high-temperature pyrolysis was determined using electron paramagnetic resonance (EPR) spectroscopy. The CuIX in carbon heated to 380°C showed the characteristic EPR signal of a planar copper (II) complex, but this signal largely disappeared when the material was heated above 400°C. For CuPc2S and CuPc-8gx, EPR confirmed the thermal stability of these complexes up to 500<sup>o</sup>C. However, SEM imaging of the CuPc2S, showed that the presence of large agglomerates in the macropores indicating that phthalocyanine was not substantially incorporated into the carbon. CuPc-8gx appears to be largely dispersed in the carbon. Fluorescence quenching experiments are consistent with the incorporation of CuPc-8gx into the head groups of the F127 surfactant leading to their widespread dispersion into the carbon, whereas CuPc2S is much less associated with the F127 micelles and so ends up in the solvent rather than incorporated into the polymer formed.

Incorporating thermally stable ligands into hierarchically porous carbon to study the stability using EPR.

ACS Spring Meeting 2021

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