Ru-modulated morphology and electronic structure of nickel organic framework bifunctional electrocatalyst for efficient overall water splitting

Metal-organic frameworks (MOFs) are considered as prospective electrocatalysts for water splitting due to their adjustable pore structure and abundant active sites. However, the rational design of MOFs with excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performances is still an enormous challenge. Herein, Ru-doped nickel thiophene dicarboxylic acid (Ni-TDA)/nickel foam (NF) were prepared via a one-pot solvothermal method, and their morphologies and electronic structures can be facilely modulated by Ru doping contents. The as-prepared self-supporting Ni5Ru-TDA/NF with Ni/Ru molar ratio of 5:1 show the excellent OER and HER activities with low overpotentials of 235 and 35 mV at a current density of 10 mA cm-2 in 1 M KOH, respectively. Furthermore, Ni5Ru-TDA/NF indicate the remarkable stability during the process of OER and HER with the slight decrease after the stability test of 60 h. The excellent electrocatalytic activities can be attributed to high intrinsic activity of multiple Ru species, the synergistic effect of Ru and Ni sites and abundance active sites in Ru-doped Ni-TDA. The water electrolysis system using Ni5Ru-TDA/NF as the anode and cathode, respectively, can achieve a current density of 10 mA cm-2 with a cell voltage of only 1.53 V, which is promising for practical applications.