Templated-preparation of a three-dimensional molybdenum phosphide sponge as a high performance electrode for hydrogen evolution

Electrocatalysts play a vital role in electrochemical water-splitting for hydrogen production. Here, we report the preparation of three-dimensional molybdenum phosphide (MoP) as a non-precious-metal electrocatalyst for the hydrogen evolution reaction (HER) by using cheap sponge (polyurethane, PU) as a sacrificial template. The obtained 3D MoP not only has large surface area, but also possesses a porous and channel-rich structure, in which the side walls of the pores are composed of refined nanoparticles. The 3D MoP sponge was used as a bulky and binder-free HER electrode and exhibited excellent catalytic activity in an acidic electrolyte (achieving 10 and 20 mA cm^-2 at an overpotential of 105 and 155 mV, respectively). In addition, this novel bulky HER electrode showed a relatively small Tafel slope of 126 mV dec^-1, a high exchange current density of 3.052 mA cm^-2, and a faradaic efficiency of nearly 100%. Furthermore, this bulky electrode revealed high tolerance and durability both under acidic and basic conditions, maintaining 96% and 93% of its initial catalytic activity after continuous testing for 60000 s. Thus, our work paves a feasible way of fabricating a cheap and highly efficient HER electrode on a large-scale for electrochemical water-splitting technology.