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

• Published in: Applied catalysis. B, Environmental Environmental, 2020-08, Vol.270, p.118878, Article 118878
• Main Authors: Wang, Kaixuan, Miao, Chenglin, Liu, Yanan, Cai, Luoyu, Jones, Wilm, Fan, Jiaxuan, Li, Dianqing, Feng, Junting
• Format: Article
• Language: English
• Subjects: Carbon; Carbon defect; Carbon dioxide; Catalysts; CO2 photoconversion; Composite materials; Conduction; Conduction bands; Defects; Electrons; Graphene; Hydroxides; Layered double hydroxide/graphene oxides composite; Light effects; Reduction; Selectivity; Ti3+-Vo; Vacancies; Valence
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2020.118878

[Display omitted] •Ultrathin LDH/GO composites are fabricated for CO2 photoreduction.•Ultrathin LDH coupled with 5% GO shows preferable selectivity and stability.•The decrease of LDH/GO thickness results in the greatly increased vacancy sites.•Joint role of Ti3+-Vo and GO addition expands absorption range to visible light.•Adsorption/activation of CO2 are mainly promoted by electron-rich carbon defects. 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 H2.