Cobalt (II)-based open‐framework systems constructed on g-C3N4 for extraordinary enhancing photocatalytic hydrogen evolution

Developing a low-cost co-catalyst for hydrogen evolution reaction (HER) on a photocatalyst is a great challenge. An open-framework material, cobalt ethylenediammonium bis(sulfate) tetrahydrate, was initially used as an efficient co-catalyst to improve photocatalytic HER of g-C 3 N 4 . The unique open‐framework cobalt(II) sulfate (Co-S) lead to twice higher H 2 evolution performance (10328.9 μmol g −1  h -1 ) compared to noble metal (Pt)-decorated g-C 3 N 4 photocatalyst under simulated sunlight. The open network structure provides abundant active sites and excellent electron transport properties, properties and then promotes electron-hole separation, which play a synergistic role with g-C 3 N 4 in the photocatalytic process. The loading of Co-S significantly changes the microenvironment of the catalyst surface of g-C 3 N 4 and enhances its hydrophilicity, which benefits the release of the produced gas on the catalyst surface. The formation of the Co(Ⅰ) species in the open-framework material by the electron reduction of Co(Ⅱ) is proposed as a vital role in the extraordinary HER process.