Single Atom Ruthenium-Doped CoP/CDs Nanosheets via Splicing of Carbon-Dots for Robust Hydrogen Production.

Ultrathin two-dimensional catalysts are attracting attention in the field of electrocatalytic hydrogen evolution. This work describe a composite material design in which CoP nanoparticles doped with Ru single-atom sites supported on carbon dots (CDs) single-layer nanosheets formed by splicing CDs (Ru1 CoP/CDs). Small CD fragments bore abundant functional groups, analogous to pieces of a jigsaw puzzle, and could provide a high density of binding sites to immobilize Ru1 CoP. The single-particle-thick nanosheets formed by splicing CDs acted as supports, which improved the conductivity of the electrocatalyst and the stability of the catalyst during operation. The Ru1 CoP/CDs formed from doping atomic Ru dispersed on CoP showed very high efficiency for the hydrogen evolution reaction (HER) over a wide pH range. The catalyst prepared under optimized conditions displayed outstanding stability and activity: the overpotential for the HER at a current density of 10 mA cm-2 was as low as 51 and 49 mV under alkaline and acidic conditions, respectively. Density functional theory calculations showed that the substituted Ru single atoms lowered the proton-coupled electron transfer energy barrier and promoted H-H bond formation, thereby enhancing catalytic performance for the HER. The findings open a new avenue for developing carbon-based hybridization materials with integrated electrocatalytic performance for water splitting.