Hollow core-shell LDH@N-HCS/CN S-scheme photocatalyst with the enhanced visible-light activity

Abstract

It is a great challenge to effectively increase the charge separation and active sites of earth-abundant graphitic carbon nitride (CN) semiconductors to improve the photocatalytic performance. Looking for a highly active cocatalyst has attracted attention because of their potential to resolve the issues of low charge separation and low specific surface area of CN. A core-shell cocatalyst composed of nitrogen doped hollow carbon spheres (N-HCS) as the core and LDH nanoplates as the photoactive shell has been designed to increase the pristine CN active sites and charge separation. N-HCS acted as the support for LDH nanoplates to prevent particle agglomeration and served as the fast electron transfer channels to enhance the photoinduced charge separation efficiency. The ternary nanocomposites exhibited superior activity for nonyl phenol and Acid Blue 92 degradation compared to the unmodified CN under the visible light. The optimized deposition of LDH@N-HCS (15 wt%) on the CN surface resulted in 7-fold higher activity than without the cocatalyst. The improved photocatalytic activity of the ternary composite compared to CN could be attributed to two factors: efficient electron-hole pair separation due to LDH nanoplates and CN interface, and the presence of the N-HCS as an electron collector. The porous hollow structure of the cocatalyst exposes the numerous surface-active sites that favor visible light photocatalytic performance and supplies multiple reflection of photons into the cavity, increasing the usage ratio of light. This work will supply a novel strategy to rationally fabricate a noble metal-free binary cocatalyst for efficient visible light activity.