Ion-change promoting Co nanoparticles@N-doped carbon framework on Co2SiO4/rGO support forming “double-triple-biscuit” structure boosts oxygen evolution reaction

Abstract

Exploring economic and high-performance electrocatalysts to decrease the overpotential of oxygen evolution reaction (OER) and facilitate its reaction kinetics is a frontier subject in line with green energy. Herein, metal-organic framework (MOF)-derived Co nanoparticles@N-doped carbon (Co NPs@N,C) is rationally designed on sandwich-like cobalt silicate/reduced graphene oxide (Co₂SiO₄/rGO) support to acquire Co NPs@N,C/Co₂SiO₄/rGO “double-triple-biscuit”-like structure as enhanced OER electrocatalysts. Co NPs@N,C on Co₂SiO₄/rGO support optimizes its geometric architecture and introduces new active sites. The “double-triple-biscuit”-like Co NPs@N,C/Co₂SiO₄/rGO structure achieves excellent OER ability compared with the existing materials based on transition metal silicates (TMSs). The overpotential of 278 mV is achieved at the current density of 10 mA cm⁻², and it is prominently higher than Co₂SiO₄/rGO support (390 mV). This excellent OER activity is rooted in its structural peculiarity, enabling efficient ion and electron transport. Co NPs@N,C are highly dispersed on the Co₂SiO₄/rGO support, increasing the active sites and avoiding self-aggregation of Co NPs in the OER process. This work combines the advantages of Co₂SiO₄/rGO support with the triple biscuits' structure and MOF to implement the preparation of boosted Co NPs@N,C/Co₂SiO₄/rGO, and it opens a new avenue for designing novel architectures to promote the OER activity of TMSs.