ZIF-67-Derived Porous Carbon Nanosheets Decorated with Co Nanoflakes As Bifunctional Electrocatalysts for Overall Water Splitting

ZIF-67-derived Co–N–C catalysts exhibit efficient water-splitting performance and thus have attracted intense research interest. However, the serious Co agglomeration and loss of most N atoms due to high-temperature pyrolysis limit the further improvement of their electrocatalytic performance. Herein, we report a ZIF-67-derived 2D porous N-doped carbon nanosheet decorated with a Co nanoflake catalyst (Co@NC/CC-500) for OER and HER by a facile pyrolysis method at a low temperature of 500 °C. Benefiting from the ultrahigh N doping (12 atom %) and uniformly dispersed Co nanoflakes on 2D porous carbon nanosheets, which lead to a high content of Co–N active sites, the Co@NC/CC-500 catalyst exhibits outstanding performance toward the HER and OER with overpotentials of 95 and 183 mV at 10 mA cm–2 in 1 M KOH, respectively. Furthermore, the alkaline water electrolyzer using Co@NC/CC-500 as the cathode and anode catalysts can achieve a current density of 10 mA cm–2 at a cell voltage of 1.52 V. This special low-temperature production method may be extensively utilized to create precisely defined monometal or bimetal nanoflakes decorated on 2D porous N-doped carbon nanosheets for diverse electrochemical energy applications.