Controllable Thickness of Amorphous Carbon Coverage to Enhance the Activity and Stability of Transition Metals in Oxygen Evolution Reaction

Encapsulating 3d transition metals (3d TMs) in crystalline carbon is a crucial strategy for improving the activity and durability. However, it is unclear whether covering amorphous carbon can enhance catalytic activity and what the optimal thickness is. Herein, we precisely control the amorphous carbon thickness on 3d TMs. As the thickness of amorphous carbon increases, the catalytic activity of 3d TMs exhibits a volcano-type trend. Covering amorphous carbon with a thickness of ≤4–8 Å can simultaneously improve the catalytic activity and durability of 3d TM catalysts. The catalytic activity of 3d TM catalysts covered with amorphous carbon surpasses that of RuO2 film and commercial RuO2 by a significant margin. Density functional theory calculations demonstrated that covering amorphous carbon increases the density of states of the Fermi level and reduces the Gibbs free energy of intermediate adsorption, which promotes electron transfer and intermediate adsorption in the catalytic process. Our work manifests a universal strategy for improving the activity and durability of 3d TM electrocatalysts.