Integration of 3D interconnected porous microstructure and high electrochemical property for boron-doped diamond by facile strategy

•A new template-free approach for constructing porous BDD films is presented.•Integration of high-quality diamond and unique 3D interconnected porous microstructure is achieved.•3D porous BDD film exhibits high electrochemical response, wide potential window and large double layer capacitance.•Relationship between electrochemical behavior and microstructure is discussed.