Acenaphthenediimine complex-bridged porphyrin porous organic polymer with enriched active sites as a robust water splitting electrocatalyst

To realize efficient water splitting, a highly promising hydrogen evolution reaction (HER) electrocatalyst is needed for the generation of hydrogen. Herein, we demonstrate a novel acenaphthenediimine complex-bridged porphyrin porous organic polymer (NiTAPP-NiACQ) with enriched active metal sites and hierarchical pores. The as-prepared NiTAPP-NiACQ exhibits good long-term durability and remarkable HER performance in 1.0 M KOH with a low overpotential of 117 mV at 10 mA cm-2, which is comparable to many previously reported electrocatalytic HER systems. Furthermore, a simple water-alkali electrolyzer using NiTAPP-NiACQ as the cathode requires a small cell voltage of 1.59 V to deliver a current density of 10 mA cm-2 at room temperature, along with outstanding durability. NiTAPP-NiACQ features not only a metal ion as the catalytic active center in the porphyrin core but also metal ion coordination on the anthraquinone component to promote HER performance, enabling multiple metal ions as the electrocatalytic active sites for the HER reaction. The excellent HER activity of NiTAPP-NiACQ is ascribed to a combination of mechanisms. These findings highlight the viability of porphyrin-derived porous organic polymers in energy conversion processes.