Rare-metal-free hydrogen evolution reaction electrocatalysts based on metal azaphthalocyanine molecular layer for anion exchange membrane water electrolysis

In this report, we elucidated the hydrogen evolution reaction (HER) catalytic activity of different metal-azaphthalocyanine unimolecular layer (AZUL) catalysts and compared the overpotentials in alkaline electrolyte membrane water electrolysis (AEMWE). While the overpotentials are bit higher compared to Pt/C, the system utilizing the FeAzPc-4N with Sustainion® showed a low overpotential of 2.02 V at 1.0 A/cm2 and faraday efficiency of 96.3% even among the previous alternative catalysts. It is noteworthy that the AZUL catalysts are not using precious metals and even comparing with other transition metal electrocatalysts, metal atom usage is much lower because only the single transition metal atom in the azapthalocyanine macrocycle works as a catalytic site.