Three-dimensional porous ultrathin carbon networks reinforced PBAs-derived electrocatalysts for efficient oxygen evolution

Prussian blue analogues (PBAs), identified with a face-centered cubic (fcc) unit cell with transition-metal ions bridged by cyano ligands, can be used as precursors in nanomaterials for catalysis applications, but the performance is usually limited by the original large size of PBAs. We provide here a controllable thermal decomposition route for PBAs to obtain highly dispersed small-sized nanoparticles with high catalytic activity. CoFe PBA nanocubes as catalyst precursors are grown within three-dimensional porous ultrathin N-doped carbon networks (3DNC), which is constructed using mixed soluble salts as templates. The use of 3DNC as supporting matrix can not only increase the electrical conductivity and transport properties of reaction-relevant species within the catalyst material, but also supply huge specific surface and restrict the size of loaded nanoparticles. Followed by calcination in the reductive atmosphere, the PBA nanocubes are decomposed to form numerous small-sized CoFe/CoFeOx nanoparticles that are uniformly dispersed. It is interesting to find that this thermal decomposition process is assisted by 3DNC matrix because of its excellent thermal conductive property. Benefiting from the synergetic bimetal alloy/oxide composition, advantageous structural feature and favorable interfacial integration of the hybrid material, the CoFe/CoFeOx@3DNC exhibits remarkable electrocatalytic activity and stability for the oxygen evolution reaction (OER) in alkaline media. The decomposition of PBAs precursor to small-sized nanoparticles and the use of 3DNC as supporting matrix and thermal conductive agent are appealing. The integration of these two components provides an interesting hybrid catalyst system with controllable composition, delicate morphology and favorable interfacial property.