Sacrificial Zn Strategy Enables Anchoring of Metal Single Atoms on the Exposed Surface of Holey 2D Molybdenum Carbide Nanosheets for Efficient Electrocatalysis
Metal single atom catalysts (SACs) supported on an appropriate structural support have attracted considerable interest due to the fantastic metal-support interaction and unique coordination structure of metal single atoms enabling high efficient catalysis. However, precisely anchoring of SACs on the surface of transition metal carbide remains a formidable challenge, although they have been widely reported with 2D carbon-based materials such as graphene and N-doped graphene. Herein, we demonstrate a novel strategy using the sacrificial zinc in the controllable pyrolysis of metal atom doped Mo/Zn bimetallic imidazolate frameworks, which enables the designed metal single atoms (e.g., Co, Ni, Cu) to be successfully anchored on the exposed surface of the in-situ produced holey 2D Mo2C nanosheets (namely Me SAs/Mo2C). When applied as the bifunctional catalysts for both oxygen and hydrogen evolution reactions, the representative Co SAs/Mo2C endow the favorable OH* adsorption strength and ultralow overpotentials (e.g. 270 mV at 10 mA cm-2 for oxygen evolution) as well as almost three-fold turn-over frequencies (TOF) value at 1.7 V of Co SAs on nitrogen-doped carbon support. Theoretical calculations disclose that the Co-Mo3 coordination is responsible for the remarkably enhanced intrinsic catalytic capability. We showcase a disruptive pathway to anchor metal single atoms on the 2D morphological carbides for enhancing electrocatalytic performance.