In Situ Growth of Ultrafine Pt Nanoparticles onto Hierarchical Co3 O4 Nanosheet-Assembled Microflowers for Efficient Electrocatalytic Hydrogen Evolution.

The development of Pt-based electrocatalysts with high Pt utilization efficiency toward the hydrogen evolution reaction (HER) is of great significance for the future sustainable hydrogen economy. For rational design of high-performance HER electrocatalyst, the simultaneous consideration of both thermodynamic and kinetic aspects remains greatly challenging. Herein, a simple template-derived strategy is demonstrated for the in situ growth of ultrafine Pt nanoparticles onto Co3 O4 nanosheet-assembled microflowers (abbreviated as Pt/Co3 O4 microflowers hereafter) by using the pre-fabricated PtCo-based Hofmann coordination polymer as reactive templates. The elaborate preparation of such intriguing hierarchical architecture with well-dispersed tiny Pt nanoparticles, abundant metal/oxide heterointerfaces and open configuration endows the formed Pt/Co3 O4 microflowers with high Pt utilization efficiency, rich active sites, lowered energy barrier for water dissociation and expedited reaction kinetics. Consequently, the Pt/Co3 O4 microflowers exhibit superior HER activity with a relatively low overpotential of 34 mV to deliver a current density of 10 mA cm-2 , small Tafel slope (34 mV dec-1 ) and outstanding electrochemical stability, representing an attractive electrocatalyst for practical water splitting. What's more, our concept of in situ construction of metal/oxide heterointerfaces may provide a new opportunity to design high-performance electrocatalysts for a variety of applications.