Abstract

The development of robust, affordable, and efficient bifunctional electrocatalysts for practical hydrogen (H2) production remains challenging. In the present study, we propose a facile synthesis strategy using a hydrothermal method followed by sulfurization for the fabrication of Co3O4@FeCo2S4 embedded with the Mo2TiC2TX MXene on Ni foam as a catalyst for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). The introduction of the Mo2TiC2TX MXene preserves the Co3O4@FeCo2S4 structure and produces rich catalytic active intermediates to boost the OER and HER. Various characterization tools verify the presence of multiple nanointerfaces between the Co3O4@FeCo2S4 and Mo2TiC2TX, greatly increase the density of active sites and facilitate electron migration, thus reducing the kinetic barriers. As a result, the optimized Co3O4@FeCo2S4/ Mo2TiC2TX catalyst displays satisfactory overpotentials of 83.1, 173.3 and 235.1 mV at 10, 50, and 100 mA cm-2 , respectively, for the HER and of 221.6, 256.6 and 283.3 mV at 10, 50, and 100 mA cm-2 , respectively, for the OER, while also exhibiting excellent durability in a 1 M KOH solution. The Co3O4@FeCo2S4/Mo2TiC2TX catalyst is subsequently used in a water electrolyzer and produces 10, 50, and 100 mA cm-2 at low cell voltages of 1.53, 1.68, and 1.81 V, respectively, which is comparable to the activity of a benchmark Pt/C//RuO2 electrolyzer. These findings verify the potential for constructing precisely engineered electrocatalysts to facilitate H2 generation without the use of noble metals.