Edge overgrowth of spiral bimetallic hydroxides ultrathin-nanosheets for water oxidation†
The structure of edges may dramatically influence the properties of nanomaterials, so the rational design or control over the structures of the edges is required. Here we synthesized spiral ultrathin-nanosheets with overgrown edges (SUNOE) of NiFe, CoNi and CoFe bimetallic hydroxides by governing the growth rates of different directions in screw dislocation driven growth (SDDG) in nonaqueous solvents. The driving force for the SDDG is supersaturation, which could be controlled by the concentration of the different precursors, thus achieving non-uniform structures of the edges and inner sheets. NiFe, CoNi and CoFe bimetallic hydroxides possess layered structures, in which overgrown edges may prevent them from re-stacking. The as prepared SUNOE all show good performance for the oxygen evolution reaction (OER) in the electrolysis of water, and the lowest onset potential was 1.45 V (vs. RHE) (the lowest potential when the current density reached 10 mA cm−2 was 1.51 V (vs. RHE)).