Self-crosslinking carbon dots loaded ruthenium dots as an efficient and super-stable hydrogen production electrocatalyst at all pH values

Highlights: • Small and homogeneous Ru dots in organic solvent were successfully synthesized. • A novel and cost-efficient membrane structure by self-crosslinking of carbon dots was presented. • The composite Ru@SC-CDs exhibited outstanding activity and stability in catalyzing hydrogen evolution at all pH values. • The Ru@SC-CDs retained 96.7% of the current density after 40 h and can maintain its activity even after 100 h of testing. -- Abstract: Development of cost-effective, high-performance electrocatalysts for hydrogen evolution reaction (HER) is urgently needed. Here, a novel HER catalyst is described where ruthenium dots are loaded into self-crosslinking carbon dots (Ru@SC-CDs) via a hydrothermal process. The optimum ratio of metal to carbon has been explored with varying proportions of ruthenium dots to self-crosslinking carbon dots (SC-CDs). Ru@SC-CDs possesses excellent HER activity with a low overpotential of 10 mA cm⁻² (59 mV in 0.5 M H₂SO₄, 66 mV in 1 M PBS and 29 mV in 1 M KOH), superior to the most noble metals, non-noble metals and non-metallic catalysts and comparable to current commercial Pt/C under the same conditions. Moreover, such catalyst shows excellent stability at all pH values, which can maintain its activity even after 100 h test, superior to that of commercial Pt/C. Density functional theory calculations suggest that the co-existence of SC-CDs and Ru dots enhanced the hydrogen generation, and in turn led to HER activity better than that of Pt. Notably, Ru@SC-CDs display outstanding performance over a wide temperature range, enabling widespread application.