Boron-doped cobalt-iron bimetal phosphides nanosheets for enhanced oxygen evolution

Developing highly efficient earth-abundant catalysts for the electrochemical oxygen evolution reaction (OER) is essential to promote the commercial application of water splitting. Herein boron-doped cobalt-iron bimetal phosphides nanosheets as OER electrocatalysts have been successfully prepared by hydrothermal boronation of bimetallic metal-organic frameworks precursors with the subsequent low-temperature phosphidation. The synergistic effect between non-metal elements (B and P) and metals (Co and Fe) is found to play an important role on tuning the local electronic configuration surrounding the active metal centers. Moreover, the resultant nanosheet structures are beneficial for exposing the catalytically active sites and facilitating the mass/charge transport. As expected, the optimal catalyst exhibits superior catalytic performance toward the OER with long-term durability in 1.0 M KOH, affording a current density of 10 mA cm−2 at low over-potential of 294 mV and small Tafel slope of 49.5 mV dec−1.