Constructing bimetal-complex based hydrogen-bonded framework for highly efficient electrocatalytic water splitting

We present herein a new concept of hydrogen-bonded organic framework (HOF) material for highly effective electrocatalysis of overall water splitting. This HOF material, namely HOF-Co, was synthesized based on very cheap raw materials. Crystallizing bimetallic HOFs of HOF-CoxFe1-x on nickel foam (NF) can be also easily obtained via a step-by-step approach. In 1 M KOH, HOF-Co0.5Fe0.5 on the NF enables both excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance, thus leading to highly effective electrocatalysis of water splitting with a cell voltage of just 1.63 V at 10 mA cm−2. The vaule is comparable to the commercial Pt/C//IrO2 (1.59 V) and other established outstanding electrocatalysts. The mechanism, as evidenced by Density Functional Theory (DFT) calculations, is due to a significant synergistic effect from the abundant hydrogen-bond structure between coordinated water molecules and SO42- ions that affords rich and accessible active sites, in conjunction with the bimetallic effect.