Highly Efficient Water Splitting with Pd-Integrated NiAl-LDH Nanosheets as Bifunctional Electrocatalysts

Electrochemical water splitting is one among multiple ways toward attaining clean energy systems, which demand efficient bifunctional catalysts. In this study, we report the synthesis of Pd-embedded NiAl-layered double hydroxide (LDH) nanosheets by a well-known coprecipitation technique, which showed superior performance in this reaction due to highly dispersed Pd in the sheets. Enhanced catalytic performance was achieved for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) using as-prepared Pd-NiAl-LDH nanosheets in a 1.0 M KOH solution. The Pd-NiAl-LDH materials exhibited substantially improved activity, stability, and overpotential, with the Tafel value for OER being 264 mV (99.5 mV/dec) and HER being 189 mV (133.2 mV/dec) at 10 mA/cm2. Pd-NiAl-LDH electrocatalyst remained stable for 48 h with minimal potential deviations observed in both OER and HER. Moreover, Pd-NiAl-LDH materials showed better activity than NiAl-LDH. With the active bifunctional Pd-NiAl-LDH electrode pair, we successfully fabricated a water electrolyzer achieving a current density of 10 mA/cm2 at a cell voltage of 1.59 V. The Pd-NiAl-LDH //Pd-NiAl-LDH configuration showed good stability over 48 h with a minimal potential deviation during the overall water splitting. Continuous generation of hydrogen and oxygen is conceivable in the solar cell configuration using the active bifunctional Pd-NiAl-LDH electrocatalyst, enabling hydrogen production in a large scale with a cell voltage of 1.60 V.