Nickel-Doped Carbon–Silica Electrocatalysts Prepared from Coal Gasification Slag for Sustainable HER

Abstract Electron transport, electrolyte accessibility, and structural stability are three key factors that influence hydrogen evolution reaction (HER) activity and catalyst durability. In this study, a coal gasification slag waste-derived carbon–silica (C@SiO2) support was used to prepare Ni-based HER electrocatalysts. The catalyst (rNi/C@SiO2) was prepared through chemical reduction of Ni impregnated in C@SiO2, followed by hydrothermal treatment. In 1.0 M KOH, rNi/C@SiO2 achieved an overpotential of 240 mV at 10 mA cm–2, a Tafel slope of 180.64 mV dec–1, a charge-transfer resistance of 32.37 Ω, an electrochemically active surface area of 609.75 cm2, stability for 15 h at 50 mA cm–2, and only slight degradation after 1000 cycles. The advantages of rNi/C@SiO2 are attributed to the slit-like mesoporous structure of C@SiO2 and dominant fcc Ni(111). The hydrophilic SiO2 and highly mesoporous structure of C@SiO2 enhance KOH–H2O infiltration in rNi/C@SiO2. The fcc Ni(111) contributes to the reduction of charge transfer resistance, thus enhancing HER. This study has shown a sustainable approach to use industrial waste as a catalyst support for hydrogen production.