Enhanced electrochemical oxygen reduction reaction on “C–O–Si” bonds in Si-doped graphene-like carbon

Abstract

The use of heteroatom-doped carbon materials as non-precious metal catalysts for oxygen reduction reactions has attracted much attention from researchers. This paper presents the synthesis of two-dimensional Si-doped graphene-like materials (Si-GLC) featuring “C–O–Si” bonds through an in-situ doping method. Since the electronegativity of the Si (1.90) is much smaller than that of C (2.55) and O (3.44), the formation of the “C–O–Si” bond causes Si to lose a large number of electrons and become positively charged. This increases the adsorption of electronegative oxygen, thereby improving the activity of oxygen reduction reactions. The adsorption energy of oxygen molecules on Si-GLC was calculated to be −3.57 eV using density functional theory, much lower than on GLC (−2.18 eV). This suggests that Si doping enhances the adsorption of oxygen molecules by graphene-like materials, which is crucial for improving the performance of oxygen reduction reaction. Si-GLC displayed a half-wave potential of 0.80 V (vs. RHE) and a diffusion-limited current density of 5.81 mA cm⁻² in 0.1 M KOH solution, demonstrating excellent catalytic activity for oxygen reduction reaction. It also exhibits good stability and tolerance to methanol crossover effect. In-situ doping creates “C–O–Si” bonds, modulating charge density and providing a strategy for high-performance oxygen reduction catalysts.