Partial Sulfurization of a 2D MOF Array for Highly Efficient Oxygen Evolution Reaction.

A feasible strategy for the in situ growth of two-dimensional (2D) [Ni3(OH)2(1,4-BDC)2-(H2O)4]·2H2O (Ni-BDC; 1,4-BDC = 1,4-benzenedicarboxylate) and the subsequent partial sulfurization treatment for the decoration of nickle sulfide (NiS) is developed. The fabricated hierarchically structured Ni-BDC@NiS as a synergistic electrocatalyst shows extremely high activity toward the oxygen evolution reaction (OER). The optimal Ni-BDC@NiS catalyst acquires a current density of 20 mA cm-2 at a lower overpotential of 330 mV and low Tafel slope of 62 mV dec-1, outperforming most previously reported Ni-based sulfide catalysts. Clearly, the combination of the NiS and Ni-BDC array contributed to the improvement of electron transfer, promotion of water adsorption, and increase of rich active species. In addition, the in situ created hierarchical structure not only affords feasible access for mass transport but also strengthens structural integrity, contributing to efficient and stable OER performance. This general and effective strategy anchoring conductive active species on a porous metal-organic framework (MOF) thus provides an efficient way to fabricate synergistic electrocatalysts for the OER.