A sacrificial Zn strategy enables anchoring of metal single atoms on the exposed surface of holey 2D molybdenum carbide nanosheets for efficient electrocatalysis

Abstract

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 highly efficient catalysis. However, precisely anchoring SACs on the surface of a 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 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, and 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 a bifunctional catalyst for both oxygen and hydrogen evolution reactions, the representative Co SAs/Mo₂C provides favorable OH* adsorption strength and ultralow overpotentials (e.g. 270 mV at 10 mA cm⁻² for oxygen evolution) as well as a 2.37-fold higher turn-over frequency (TOF) value at 1.7 V of Co SAs on a 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 2D morphological carbides for enhancing electrocatalytic performance.