High-performance hydrogen evolution reaction by ReS2/TiO2 hollow microcones created through microwave-hydrothermal consecutive synthesis†

There is a need to develop a high-performance and low-cost hydrogen evolution reaction (HER) catalyst without noble metal. Transition metal dichalcogenides are some of the most promising catalytic materials, and rhenium disulfide (ReS₂) emerges as a favorable material due to its unique structural properties. However, ReS₂ is still lacking in research for effective catalytic performance; especially, increasing the electrochemical surface area has not been investigated. Herein, we present a 3D-structured ReS₂/TiO₂ catalyst with a high electrochemically active surface area (ECSA) obtained through a simple two-step process: (i) formation of TiO₂ hollow microcones by microwave treatment and ReS_2−x coating and (ii) ReS₂ nanowall formation by a hydrothermal process. The microconical structure of the catalyst obtained via the two-step process significantly improved the HER activity of ReS₂, exhibiting a low overpotential (61 mV), and a large ECSA (3652 cm²) with negligible degradation after 10 000 cycles of potential scanning and for 72 h of chronopotentiometric measurements at a current density of 500 mA cm⁻², which is a superior result compared to previously reported ReS₂-based HER catalysts.