Supercritical CO2-Induced Ferromagnetism in 2D C3N4 for Catalysis in Hydrogen Evolution Reaction.

The exploration of high-efficient catalysts has been an essential challenge for electrocatalytic hydrogen evolution reaction (HER). Herein, two-dimensional (2D) amorphous carbon nitride (a-C3N4) with obvious ferromagnetism was achieved through a typical supercritical CO2 (SC CO2) treatment process. The experimental results revealed the structural and chemical transformations during the formation of a-C3N4. Subsequently, a-C3N4 anchored with Ru nanoparticles (Ru/a-C3N4) was successfully synthesized and employed as a catalyst for the electrocatalytic HER, exhibiting a significantly enhanced catalytic performance compared to Ru nanoparticles anchored on 2D graphitized carbon nitride (g-C3N4) without SC CO2 treatment. DFT calculations further demonstrate that the ferromagnetic g-C3N4 substrate not only promotes disassociation of water molecules under alkaline conditions, but also influences the charge distribution and modulates the free energy of H adsorption, finally accelerating the HER kinetics. These results impart significant insights into the electrocatalytic HER process and establish a foundation for the design of advanced catalysts with enhanced performance for energy conversion and storage applications.