Highly graphitic carbon shell on molybdenum carbide nanosheets by iron doping for stable hydrogen evolution

The graphitic degree of carbon layer on molybdenum carbide (MC) surface might affect its catalytic performance toward the hydrogen evolution reaction (HER). In this study, an iron (Fe)-doping method was investigated to adjust the graphitic degree of the carbon layer, and subsequently explore the catalytic activity of the generated MCs. A series of Fe-doped MCs was synthesized, and the optimization of their doping level led to distinctly higher HER activity compared to the undoped MC, in both acidic and alkaline solutions, due to the electronic effect. Transmission electron microscopy was applied to determine carbon-coated structure of the obtained Fe-doped MCs while Raman spectra demonstrated the successful adjustment of the carbon layer's graphitic degree with the change of the doping level. As a result, the well-preserved catalytic activity after a 10,000-circles stability test indicated the stable performance of HER on the Fe-doped MC, whereas the enhanced durability was supported by the high graphitic degree of carbon coating layer.