One-step preparation of ZnTi-LDH/graphene nanosheet hybrids in supercritical ethanol based on an exfoliation-reassembly strategy and their enhanced photocatalytic performance

Abstract

This study proposed a one-step preparation method for ZnTi-layered double hydroxide (ZnTi-LDH)/reduced graphene oxide (rGO) nanosheet hybrids in a supercritical ethanol system. After treating pristine ZnTi-LDH and rGO in the supercritical state of ethanol (268 °C, 10 MPa) for 1 h, nanocomposites composed of LDH nanosheets (7–10 nm in thickness) and rGO were obtained. Based on the conversion of ethanol between supercritical and conventional states, this method achieves the exfoliation of LHD nanosheets and reassembly with rGO in one step. This method promotes the generation of oxygen vacancies (OVs) favorable for electron-hole pair separation on the LDH/rGO surface. In the photocatalytic degradation of organic dyes, the degradation rate constants of LDH/rGO composites for Rhb and AO7 are 2.9 and 3.3 times that of pristine LDH, respectively. The enhanced photocatalytic activity was attributed to the OVs on the LDH/rGO surface, the positively charged LDH nanosheets, and the electrical conductivity of rGO.