Pt nanodots monolayer modified mesoporous Cu@CuxO nanowires for improved overall water splitting reactivity

Highlights: • Low surface loading of Pt nanodots (0.48 at%) on mesoporous Cu@Cu_xO NWs was prepared. • Ultra-small Pt nanodots along with its electronic modulation improved HER process. • Unique dendritic nanostructures of vertical Cu_xO layers on Cu NWs improved OER. • Synergetic effect of Pt and Cu-based materials accelerated overall water splitting. • The catalyst had better catalytic and mass activity, stability than Pt/C and RuO₂. -- Abstract: A Pt nanodots monolayer with ultra-low surface loading of 0.48 at% integrating onto a mesoporous complex nanostructure of Cu@Cu_xO nanowires (NWs) supported by a three-dimensional substrate is developed via a versatile and effective deposition strategy of the galvanic displacement between Cu monolayer and PtCl₄^2- in an effort to minimize Pt catalyst usage. The uniform and ultra-small Pt nanodots (∼2 nm) achieved full coverage on NWs leads to significant structural modulation, along with increased hierarchical and disorder degree. It also generates high Pt-Cu interaction, as evidenced by the crystal lattice deformation of metallic phases and the charge transfer from Cu to Pt, leading to enhancement towards both of hydrogen evolution (HER) and oxygen evolution (OER) processes. The hybrid exhibits low overpotential values of 72 mV and 250 mV at 10 mA cm⁻² for HER and OER, respectively, and these are superior to those of other surveyed materials. The mass activity of hybrid is around 3.1 times higher than commercial Pt-C (10 wt%) for HER and 6.4 times higher than Pt-C and RuO₂-C for OER under similar testing conditions. This research may serve as a promising method for developing electrocatalysts with high activity but minimal Pt usage towards water splitting.