Designing one-compartment HO fuel cell using electroactive phenalenyl-based [Fe(hnmh-PLY)] complex as the cathode material

The sustainable chemical energy of H 2 O 2 as a fuel and an oxidant in an advantageous single-compartment fuel cell design can be converted into electric energy, which requires molecular engineering to design suitable cathodes for lowering the high overpotential associated with H 2 O 2 reduction. The present work covers the synthesis and structural characterization of a novel cathode material, [Fe III 2 (hnmh-PLY) 3 ] complex, 1 , designed from a PLY-derived Schiff base ligand ( E )-9-(2-((2-hydroxynaphthalen-1-yl)methylene)hydrazineyl)-1 H -phenalen-1-one, hnmh-PLYH 2 . Complex 1 , when coated on the surface of a glassy carbon electrode ( GC-1 ) significantly catalyzed the reduction of H 2 O 2 in an acidic medium. Therefore, a complex 1 modified glassy carbon electrode was employed in a one-compartment H 2 O 2 fuel cell operated in 0.1 M HCl with Ni foam as the corresponding anode to produce a high open circuit potential (OCP) of 0.65 V and a peak power density (PPD) of 2.84 mW cm −2 . CV studies of complex 1 revealed the crucial participation of two Fe( iii ) centers for initiating H 2 O 2 reduction, and the role of coordinated redox-active PLY units is also highlighted. In the solid state, the π-conjugated network of coordinating (hnmh-PLY) ligands in complex 1 has manifested interesting face-to-face π-π stacking interactions, which have helped the reduction of the complex and facilitated the overall catalytic performance. The sustainable energy of H 2 O 2 in single-compartment fuel cell can be converted into electric energy, requiring molecular engineering to design suitable cathodes to lower the high overpotential associated with electrochemical H 2 O 2 reduction.