Large-Scale Synthesis of Co/CoO_x Encapsulated in Nitrogen-, Oxygen-, and Sulfur-Tridoped Three-Dimensional Porous Carbon as Efficient Electrocatalysts for Hydrogen Evolution Reaction

A facile and scalable one-step thermal treatment method is developed to produce Co/CoOx encapsulated in N-, O-, and S-tridoped three-dimensional porous carbon material to catalytic hydrogen evolution reaction. Notably, the process is simply performed via pyrolysis of a solid carbon source of filter paper with adsorbed moderate cobalt chloride and thiourea. Benefiting from the high conductivity and porosity of N-, O-, and S-tridoped three-dimensional porous carbon, the high stability of carbon-protected nanomaterials and the strong interactions between Co and CoOx, the resulting Co/CoOx encapsulated in N-, O-, and S-tridoped three-dimensional porous carbon material (synthesized at 900 °C) can yield the current densities of 10 mA cm–2 at a small overpotential of 61 mV and show a low Tafel slope of 78 mV dec–1, as well as a considerable stability in alkaline medium (1.0 M KOH solution) for hydrogen evolution reaction. Compared with other referential catalysts, the electrochemical impedance spectroscopy of Co/CoOx encapsulated in N-, O-, and S-tridoped three-dimensional porous carbon material (synthesized at 900 °C) further reveals a favorable kinetics during electrolysis. Moreover, these findings may inspire the exploration of low-cost, efficient, and high-yield three-dimensional porous electrodes for practical hydrogen production.