N-Doped sp 2 /sp 3 Carbon Derived from Carbon Dots to Boost the Performance of Ruthenium for Efficient Hydrogen Evolution Reaction.

The structure and properties of the carrier significantly affect the catalytic activity of the active centers for supported electrocatalysts. Therefore, elaborate design and regulation of the physicochemical properties of carbon carriers are essential to improve the activity and stability of the carbon-supported ruthenium-based catalysts. Herein, enlightened by the unique characteristics of coexisting sp 2 and sp 3 carbon nuclei in N-doped carbon dots (NCDs), a hybrid structure of N-doped carbon substrates featuring N-doped sp 2 /sp 3 carbon interfaces loaded with Ru nanoparticles (Ru/NCDs) is obtained. Spectroscopic analysis and density functional theory calculations illustrate that the interaction between Ru and NCDs effectively modulates the electronic structure of the active center Ru, and the formed N-doped sp 2 /sp 3 carbon interface lowers the energy barrier of the intermediates in hydrogen evolution reaction (HER) and balances the hydrogen adsorption and desorption and, thereby, greatly improves the activity of Ru/NCDs. Remarkably, Ru/NCDs exhibit excellent HER activity and stability in comparison to Pt/C, which merely requires overpotentials as low as 37 and 14 mV at 10 mA cm -2 in alkaline and acidic electrolytes, respectively. This finding will provide more thoughts about the influence of substrate properties on the catalytic activity and rational design of carbon-loaded electrocatalysts.