Enhancing electrocatalytic total water splitting at few layer Pt-NiFe layered double hydroxide interfaces

Formation of NiFe layered double hydroxide (LDH) with Pt NPs was achieved following a two-step reaction viz., the hydrothermal preparation of highly crystalline NiFe LDH sheets and the homogenous reduction of Pt⁴⁺ ions with borohydride in a solution of homogenized NiFe LDH crystalline sheets. Chemically equivalent NiFe LDH material decorated with Pt NPs was prepared by co-precipitation for comparative studies. The synthesized catalysts were systematically screened for oxygen and hydrogen evolution reactions (OER and HER) in 1 M KOH. The intentional incorporation of Pt NPs on the LDH layers reduced the cell voltage and delivered high current densities with a lower loading of 0.205 mg cm⁻². The NiFe LDH crystalline sheets had shown significantly enhanced activity, good stability, lower overpotential (90 mV) at 10 mA cm⁻² and lower Tafel slope (12 mV dec⁻¹) than the co-precipitated NiFe LDH in OER. Similarly, Pt NPs tethered NiFe LDH crystalline sheets showed better activity by having lower overpotential (27 mV) and Tafel slope (51 mV dec⁻¹) than the co-precipitated NiFe LDH with Pt NPs. Moreover, the state-of-the-art catalysts viz., IrO₂ and Pt/C 20 wt% of OER and HER failed in competing with Pt NPs tethered NiFe LDH crystalline sheets.