  Hydrogen is a promising energy carrier for replacing fossil fuels, and
hydrogen production via hydrogen evolution reaction (HER) is an environmentally
friendly option if electrocatalysts with low overpotentials and long-term
stability are used. In this work, the electrocatalytic performance of
$\mathrm{Pt_{57.5}Cu_{14.7}Ni_{5.3}P_{22.5}}$ bulk metallic glass (BMG) with
flat, micro-patterned, and nano-patterned surfaces for HER in 0.5 M H2SO4 is
studied. The nano-patterned Pt-BMG demonstrates outstanding long-term stability
and self-improving behavior with a final overpotential of 150 mV and a Tafel
slope of 42 $\mathrm{mV dec^{-1}}$ after 1000 linear sweep voltammetry (LSV)
cycles, which is respectively 42% and 37% lower than in the first LSV cycle.
X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES)
indicate the formation of a layer of CuO/Cu2O foam deposited on top of the
nano-patterned surface during the stability test of 1000 LSV cycles. A
three-step process is proposed to explain the formation of CuxO foam via
dynamic hydrogen bubble templating (DHBT) electrodeposition from Cu dissolution
of the Pt-BMG without using copper salt. This work provides a method to create
CuxO foams that could be used for various applications. Moreover,
nano-patterned BMGs with DHBT deposition offer a feasible strategy to
synthesize metal or metal-oxide foams.
