Fabrication of a novel superaerophobic support structure for NiCo-layered double hydroxide electrocatalysts for the oxygen evolution reaction

In this work, 3D Ni substrate with superaerophobic properties were catalyzed through the deposition of NiCo layered double hydroxide (NiCo-LDH). Deposition of NiCo-LDH was achieved using a mixed solution of Ni and Co nitrate salts as precursors. Precipitation of NiCo-LDH was achieved by the application of a negative current that caused a local raise of the solution pH. NiCo-LDHs were deposited in the form of vertically aligned nanosheets that infiltrate throughout the porous structure of the superaerophobic 3D Ni substrate. Variation of the deposition current changed the composition of the NiCo-LDH. The performance and the mechanisms responsible for the OER were investigated through a series of electrochemical experiments that include electrochemical impedance spectroscopy. As exemplified by a change of the Tafel slope from ca. 60 to 40 mV/decade, the OER mechanism is modified by the deposition the NiCo-LDH. In 1 M KOH at room temperature, the best electrode has overpotential as small as 269 and 340 mV at 10 and 250 mA cm-2, respectively. Longer-term electrolysis test during 56 h at 250 mA cm-2 showed a constant overpotential of 340 mV, without any sign of degradation.