Enhanced bifunctional water electrolysis activities of activated carbon-decorated trimetallic Ni-Al-La nanocomposites

Developing inexpensive, durable, and high-performance trimetallic catalysts is critical for producing hydrogen and oxygen through electrocatalytic water splitting. In this study, activated carbon-decorated trimetallic Ni-Al-La (AC-TM) nanocomposites were synthesized via a facile ultrasonication process using coprecipitation-derived TM nanoparticles and pyrolytically fabricated biomass AC nanosheets. The resulting AC-TM nanocomposites exhibited a microstructure consisting of AC-anchored TM nanoparticles with a high specific surface area of 64 m²/g. For the oxygen evolution reaction (OER), the AC-TM catalyst demonstrated excellent electrocatalytic activity, achieving a low overpotential of 180 mV and a Tafel slope of 52 mV/dec, alongside outstanding stability at 10 mA/cm² in 1 M KOH. Similarly, for the hydrogen evolution reaction (HER), the AC-TM catalyst exhibited a low overpotential of 195 mV and a Tafel slope of 93 mV/dec with good durability. Consequently, the AC-TM nanocomposites delivered exceptional overall water-splitting performance, requiring a low full-cell voltage of 1.57 V at 10 mA/cm² and maintaining long-term durability for up to 100 h. The remarkable performance of the AC-TM nanocomposites can be attributed to the synergistic effect of the high conductivity of the AC nanosheets and the enhanced catalytic active surface area provided by the TM nanoparticles. These findings indicate that AC-TM nanocomposites are highly suitable as bifunctional electrocatalyst materials for efficient water splitting.