Vacancy enriched ultrathin TiMgAl-layered double hydroxide/graphene oxides composites as highly efficient visible-light catalysts for CO2 reduction

Ti-containing layered-double-hydroxide (LDH) was exfoliated and coupled with ultrathin graphite (GO) by electrostatic assembly method to fabricate LDH/GO composites for visible-light-driven reduction of CO2. Main focus was to explore the types and quantities of vacancies dependent light response range and product distribution. Interestingly, catalytic behavior of LDH/GO varied with GO ratio increasing as volcano curve, in which 5%GO/LDH exhibited superior efficiency and C1 selectivity. Primarily, delaminated LDH and GO led to structural unsaturated coordination, and thus generated Ti3+-Vo and electron-rich carbon defects. Once coupling with GO, joint function of Ti3+-Vo and transition from C1 s level to conduction band level of reduced valence states expanded absorption range to visible-light. Furthermore, adsorption/activation of CO2 was mainly promoted by electron-rich carbon defects. More importantly, with the aid of Ti3+-Vo and electron-rich carbon defects, two new radicals of HCO3- and CO2- appeared during reaction process over 5GO/LDH, prone to produce C1 rather than H-2.