Electrically conductive Pt-MOFs for acidic oxygen reduction: Optimized performance via altering conjugated ligands

Electrically conductive metal–organic frameworks (MOFs) for chemical energy storage have attracted tremendous interests recently. Here, we report Pt3(C12N6O6)2 MOF, Pt3(C12N9H3O3)2 MOF, and Pt3(C12N12H6)2 MOF with high conductivities of 885.5 S/m, 602.5 S/m, and 426.9 S/m, respectively, where the organic ligands and square-planar Pt ions are connected into two-dimensional (2D) MX4 configuration. We attempted to employ these layer-stacked 2D Pt-MOFs as the cathode electrocatalyst for acidic oxygen reduction reaction (ORR) based on the research background of proton exchange membrane hydrogen fuel cells. The electronic structures of Pt-MOFs were altered by varying the coordinated ligand X to optimize the acidic ORR performance. Pt3(C12N6O6)2 MOF shows the best performance, with a superior activity (E1/2 = 0.836 V vs reversible hydrogen electrode (RHE) at 1600 r.p.m, n = 3.96, and jL = 5.28 mA cm−2) and exceptional durability of up to 20,000 cycles for ORR in an acidic media with a pH of 0.29.