The critical role of Ru-like hydrogen adsorption of carbon dots in a carbon-confined Ru system for boosted HER activity

The in-depth understanding of electrocatalysts is the key issue in the fields of clean energy and the chemical industry. Although various carbon-loaded active metal particle catalysts for the electrocatalytic hydrogen evolution reaction (HER) have been developed, the interaction between active metals and the substrate is still unclear. Herein, ruthenium (Ru) nanoparticles loaded on N-doped carbon dots (Ru/NCDs) were constructed to discover the critical roles of the carbon substrate as well as its interaction with Ru. Notably, we show the two critical functions of NCDs in a carbon-confined Ru system. First, the ultra-small Ru nanoparticles increase the hydrogen spillover channels. Second, the carbon substrate shows a Ru-like hydrogen adsorption capacity, supplying sufficient H sources for hydrogen spillover. Thus, the hydrogen spillover is enhanced and the HER process is accelerated. The Ru/NCDs catalyst shows superior HER activity and durability in both acidic and alkaline solutions. This work clarifies the critical role of carbon substrates in carbon-loaded catalysts.