Scalable synthesis of porous hollow CoSe2–MoSe2/carbon microspheres for highly efficient hydrogen evolution reaction in acidic and alkaline media

Abstract

For the first time, porous microspheres of bimetallic CoSe₂–MoSe₂ hybrids with reduced graphene oxide and amorphous carbon (CS-MS/rGO-C) are synthesized through a facile, low-cost and scalable spray drying approach and a subsequent selenization process. The CS-MS/rGO-C electrocatalyst delivers excellent performance for the hydrogen evolution reaction (HER) in both acidic and alkaline media: in acidic solution, CS-MS/rGO-C has a very low onset potential of −142 mV vs. RHE and a low Tafel slope of 51.3 mV dec⁻¹, and the overpotential at −10 mA cm⁻² is as low as −195 mV vs. RHE; in alkaline media, the onset potential of CS-MS/rGO-C is −125 mV vs. RHE, and the Tafel slope is 83.2 mV dec⁻¹, and the overpotential at −10 mA cm⁻² is −215 mV vs. RHE. Moreover, it has outstanding long-term stability in both media even after 1000 cycles. The outstanding HER performance of CS-MS/rGO-C can be attributed to its bi-metallic composition, porous rGO-C microsphere structure, and conductive rGO-C skeleton, which can not only provide abundant active sites, but also guarantee high conductivity for CS-MS, thus facilitating the charge transfer. This work provides new insights into scalable synthesis of low-cost electrocatalysts with high efficiency and long-term stability, which can be extended to large-scale production of other advanced electrocatalysts to replace precious Pt-based catalysts for hydrogen evolution.