Phosphine Oxide Porous Organic Polymers Incorporating Cobalt(II) Ions: Synthesis, Characterization, and Investigation of H(2) Production

[Image: see text] Suitably functionalized porous matrices represent versatile platforms to support well-dispersed catalytic centers. In the present study, porous organic polymers (POPs) containing phosphine oxide groups were fabricated to bind transition metals and to be investigated for potential electrocatalytic applications. Cross-linking of mono- and di-phosphine monomers with multiple phenyl substituents was subject to the Friedel–Crafts (F-C) reaction and the oxidation process, which generated phosphine oxide porous polymers with pore capacity up to 0.92 cm(3)/g and a surface area of about 990 m(2)/g. The formation of the R(3)P·BH(3) borohydride adduct during synthesis allows to extend the library of phosphine-based monomeric entities when using FeCl(3). The porous polymers were loaded with 0.8–4.2 w/w % of cobalt(II) and behaved as hydrogen evolution reaction (HER) catalysts with a Faradaic efficiency of up to 95% (5.81 × 10(–5) mol H(2) per 11.76 C) and a stable current density during repeated controlled potential experiments (CPE), even though with high overpotentials (0.53–0.68 V to reach a current density of 1 mA·cm(–2)). These studies open the way to the effectiveness of tailored phosphine oxide POPs produced through an inexpensive and ecofriendly iron-based catalyst and for the insertion of transition metals in a porous architecture, enabling electrochemically driven activation of small molecules.