Scale-up synthesis of monolayer layered double hydroxide nanosheets via separate nucleation and aging steps method for efficient CO2 photoreduction

Abstract

Photocatalytic CO2 reduction is one of the most promising ways to solve the energy crisis and the greenhouse effect. Among the abundant products (CO, HCOOH, CH3OH, CH4, etc), it is difficult to reduce CO2 through 8 electrons to CH4. Monolayer layered double hydroxides (denote as LDHs) have drawn wide attention and interest due to the abundant defects and unique electronic structure. However, the monolayer LDHs can be obtained mainly in the lab scale, which seriously hindered their practical large-scale industrial application. Herein, a facile approach to synthesize monolayer LDHs was developed by modifying the industry colloid mill reactor through the addition of a small amount of layer growth inhibitor formamide using separate nucleation and aging steps (SNAS) method. The obtained monolayer LDH nanosheets by SNAS possessed a thickness of ~1 nm, with uniform lateral size and abundant defects, which exhibited superior activity in CO2 photoreduction with 81.75% selectivity to CH4 while inhibiting H2 selectivity <3% under visible light. This method is universal to different LDHs and can be used for large-scale preparation, which lays the foundation for the industrial production of monolayer LDHs.