Promotion of hydrogen evolution catalysis by ordered hierarchically porous electrodes

Abstract

A rational porous structure can efficiently enhance the electrode reaction process. In this study, we fabricated a type of three-dimensional (3D)-ordered hierarchically porous carbon via a dual-template method to support ruthenium species as efficient cathodes towards the hydrogen evolution reaction (HER). The ordered hierarchical pores comprised of three levels of porous structure, including the inverse opal-structured macroporous carbon skeleton (ca. 150 nm), the internal-ordered mesoporous structure (ca. 5 nm), and abundant microporous structure (<2 nm). Due to the binder-free and ordered hierarchically porous structure, the resultant electrode showed highly exposed active sites with enhanced mass transfer including electrolyte diffusion and hydrogen spillover during the HER process, resulting in the superior catalytic activity with a low overpotential of 58 mV at 10 mA cm⁻² in an alkaline electrolyte. Its performance is even better than the commercial RuO₂/Ni mesh cathode (75 mV) and commercial Pt/C electrocatalyst (65 mV). Moreover, the step chronopotentiometry testing also confirms that the ordered hierarchically porous electrode possesses more obvious advantages for HER catalysis at large current densities.