Synthesis, characterization and enhanced photocatalytic CO₂ reduction activity of graphene supported TiO₂ nanocrystals with coexposed {001} and {101} facets

Abstract

It is known that the combination of TiO2 and graphene and the control of TiO2 crystal facets are both effective routes to improve the photocatalytic performance of TiO2. Here, we report the synthesis and the photocatalytic CO2 reduction performance of graphene supported TiO2 nanocrystals with coexposed {001} and {101} facets (G/TiO2-001/101). The combination of TiO2 and graphene enhanced the crystallinity of TiO2 single nanocrystals and obviously improved their dispersion on graphene. The "surface heterojunction" formed by the coexposed {001} and {101} facets can promote the spatial separation of photogenerated electrons and holes toward different facets and the supports of graphene can further enhance the separation through accelerated electron migration from TiO2 to graphene. The G/TiO2-001/101 exhibited high photocatalytic CO2-reduction activity with a maximum CO yield reaching 70.8 μmol g(-1) h(-1). The enhanced photocatalytic activity of the composites can be attributed to their high surface area, good dispersion of TiO2 nanoparticles, and effective separation of excited charges due to the synergy of graphene supports and the co-exposure of {001} and {101} facets.

Surface heterojunction between (001) and (101) facets of ultrafine anatase TiO2 nanocrystals for highly efficient photoreduction CO2 to CH4

“…Particularly, some physicochemical properties are connected closely with the surface atomic configuration and the exposure of the specific facets. There are three fundamental low-index facets exposed generally in anatase TiO 2 nanocrystals: (001), (010) and (101) facets, and their average surface energies reported in the literature are 0.90, 0.53 and 0.44 J/m 2 , respectively [14][15][16]. Higher surface energy of (001) facets is more efficient for dissociative adsorption of reactant molecules compared with (010) and (101) facets, which has the high density of active unsaturated coordination Ti atoms and the presence of enlarged Ti-O-Ti bond angles on the surface [17][18][19].…”

CO 2 capture and photocatalytic reduction using bifunctional TiO 2 /MOF nanocomposites under UV–vis irradiation

“…Among them, TiO 2 materials are the most widely investigated photocatalysts due to their high stability, low cost and non-toxic nature [11][12][13]. Pure TiO 2 and TiO 2based composites of various configurations, composition and morphology at the nanoscale have been synthesized and applied in CO 2 photoreduction [14][15][16][17][18]. Overall, studies on TiO 2 have shown that photocatalytic activity is drastically affected by the exposed TiO 2 facets.…”

Defect-engineered TiO2 Hollow Spiny Nanocubes for Phenol Degradation under Visible Light Irradiation

“…These merits contribute the possibility of various photocatalytic reactions to continue under ultraviolet (UV) illumination 3 . Many endeavors have been dedicated to enhance the photoactivity of TiO 2 based nanomaterials, such as defect engineering 4 , 5 , crystal facets regulation, the surface/interface control 6 , 7 , and the complex structures 8 . Chen et al .…”