Gradient Heating Epitaxial Growth Gives Well Lattice‐Matched Mo2C−Mo2N Heterointerfaces that Boost Both Electrocatalytic Hydrogen Evolution and Water Vapor Splitting

Abstract An optimized approach to producing lattice‐matched heterointerfaces for electrocatalytic hydrogen evolution has not yet been reported. Herein, we present the synthesis of lattice‐matched Mo 2 C−Mo 2 N heterostructures using a gradient heating epitaxial growth method. The well lattice‐matched heterointerface of Mo 2 C−Mo 2 N generates near‐zero hydrogen‐adsorption free energy and facilitates water dissociation in acid and alkaline media. The lattice‐matched Mo 2 C−Mo 2 N heterostructures have low overpotentials of 73 mV and 80 mV at 10 mA cm −2 in acid and alkaline solutions, respectively, comparable to commercial Pt/C. A novel photothermal‐electrocatalytic water vapor splitting device using the lattice‐matched Mo 2 C−Mo 2 N heterostructure as a hydrogen evolution electrocatalyst displays a competitive cell voltage for electrocatalytic water splitting.