Boosting electrocatalytic water oxidation by creating defects and lattice-oxygen active sites on Ni-Fe nanosheets.

Layered nickel-iron oxide/hydroxide nanosheets have proven as the most efficient catalyst for the water oxidation reaction. Introducing structural defects to the nanosheets is a particularly attractive method for increasing the number of active sites and tailoring the intrinsic electronic properties. Herein, defects were introduced on Ni-Fe nanosheets through sequentially electrodoping and dedoping the surface of the material with tetramethylammonium ions. The as-prepared defect-rich Ni-Fe nanosheets showed an enhanced catalytic performance for OER compared with the conventional NiFe layered double hydroxides (LDHs), exhibiting an overpotential of only 172 mV at the current density of 10 mA cm -2 . The relationship between pH and OER activity indicated that the lattice oxygens have participated in the catalytic OER process as active sites. This work provides new insights into the understanding of the structure-activity relationship of layered materials, and helps to develop new methods to implement defects on such frameworks aided by organic molecules.