Platinum (Pt) is a popular electrocatalyst for the hydrogen
evolution
reaction (HER) for water splitting. However, a facile synthesis route
with improved activity and stability remains to be established. In
this study, Au–Pt bimetallic nanocomposite electrodes for the
HER are prepared by ligand-exchange-assisted layer-by-layer (LbL)
self-assembly methods. Pt and Au nanoparticles (NPs) are alternately
deposited onto Ti electrodes paired with short alkyl amines. This
process is accompanied by the removal of the preattached bulky surface
ligands. The resulting Pt and Au NP LbL nanocomposite films are characterized
by uniform thin-film depositions with high electrical conductivity
(8.7 × 104 S cm–1). With the increase
in the number of depositions, the overpotentials of the Au–Pt
LbL samples gradually decrease and reach 66 mV at a current density
of 10 mA cm–2 under an acidic condition of 0.5 M
H2SO4, which is accomplished with a significantly
small Pt loading (0.73 wt %). Furthermore, the overpotentials of the
Au–Pt bimetallic LbL films are one-third of the Pt NP LbL films.
The enhanced activity can be attributed to the synergistic effect
of the d-band shift from the bimetallic heterostructure,
high electrical conductivity, rapid charge transfer, and increased
electrochemical surface area.