Sulfur-doped NiFe(CN)5NO nanoparticles as efficient electrocatalysts for the oxygen evolution reaction

Developing low-cost and high-efficiency electrocatalytic materials for the oxygen evolution reaction (OER) is crucial and urgent for water splitting. Here, we demonstrate a novel OER electrocatalyst (S-NiFe(CN)(5)NO) prepared by constructing a bimetallic metal-organic framework (MOF) and in situ doping of sulfur. The generation of Ni-Fe active sites upgrades the structural stability and electronic conductivity of the MOF. The sulfur doping further optimizes the electronic structure, thus lowering the energy barriers for the OER. As a result, the S-NiFe(CN)(5)NO catalyst possesses excellent catalytic activity towards the OER with an ultralow overpotential of 274 mV at 10 mA cm(-2) and a small Tafel slope of 54.4 mV dec(-1) in 1.0 M KOH. Moreover, the activity can be well maintained after 1000 cycles, indicating superior electrochemical stability. The electrocatalytic performance of S-NiFe(CN)(5)NO is far superior to that of pristine NiFe(CN)(5)NO and the advanced RuO2 catalyst. It is revealed that the improved OER catalytic properties are attributed to the synergetic effect of bimetallic active sites and sulfur species in S-NiFe(CN)(5)NO. Density functional theory calculations explain that S doping can accelerate electron transport and optimize OER paths. This work is meaningful for the study of many multivariate MOFs as OER catalysts and can be extended to other energy-related fields.