Atomic Layer Deposition Inducing Integration of Co, N Codoped Carbon Sphere on 3D Foam with Hierarchically Porous Structures for Flexible Hydrogen Producing Device

Integration of metal-organic frameworks on deformation tolerant substrates exhibits a promising prospect in flexible electrode applications. A straightforward synthesis utilizing atomic layer deposition pretreating to induce the growth of a zeolitic imidazolate framework-67 (ZIF-67) layer on carbon foam (CF), which maintains high ZIF-67 loading with a hierarchically porous structure and large surface area of 453 m(2) g(-1) is presented. With a subsequent pyrolysis process, three-dimensional composite structures are obtained with Co, N codoped carbon spheres attached firmly on the CF framework, and CF bridges the individual carbon spheres to construct a conductive pathway. The composites are used as a flexible electrode for hydrogen production both in acid and alkaline electrolytes. The advances in the composite structure, such as the hierarchically porous structure, large surface area, and high loading of active material, lead to excellent electrochemical performance in terms of low overpotential of 142 mV and low Tafel slope of 73 mV dec(-1) in 0.5 m H2SO4. Most importantly, the composite structure with outstanding flexible property shows good catalytic performance under remarkable deformation, and after 100 repeated compression-recovery cycles, the performance degrades slightly. This work provides a new design of flexible electrode, which is promising for the hydrogen production industry.