The MXenes have attracted rapidly raising interests due to a well combination of wide chemicaland structural variety with a variety of attractive properties such as high conductivity,goodmechanical stability,excellent hydrophily and rich surface chemistry enabled by chemical groupsgrafted.Together with ultralow work function and electronegative surfaces,MXenes show greatpotential as the supporting matrix to tailor the electrophilicity of the active materials and theirproperties for electrochemical energy storage and conversion.In this report,we firstly show thepotential of MXene as both the matrix material and conductive agent for constructing the electrodematerials with high volumetric energy density,high power output and long lifetime for lithiumstorage.Engineering the interfacial structure of MXene by guest nanostructures(e.g.,metalhydroxides,sulfide,carbide)further leads to highly active electrocatalysts for electrochemicalwater electrolysis.We also demonstrate the construction of MXene-based 3D architectures withaggregation-resistant and kinetics-favorable properties,which act as ideal material platform forengineering high-performance electrode/electrocatalyst.