Shape‐ and Size‐Controlled Synthesis of Uniform Anatase TiO₂ Nanocuboids Enclosed by Active {100} and {001} Facets

Abstract

Uniform anatase TiO2 nanocuboids enclosed by active {100} and {001} facets over a wide size range (60–830 nm in length) with controllable aspect ratios were solvothermally synthesized through hydrolysis of titanium tetraisopropoxide (TTIP) using acetic acid (HAc) as the solvent and the ionic liquid 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim][BF4]) as the capping agent. The size and aspect ratio of the anatase TiO2 nanocuboids can be readily adjusted by changing the composition parameters including the contents of [bmim][BF4], water, and HAc in the quaternary solution system. It was revealed that [bmim][BF4] played an important role in stabilizing both the {100} and {001} facets of the anatase TiO2 nanocuboids. On the one hand, [bmim][BF4] acted as a fluoride source to release F− ions for stabilizing the {001} facets; on the other hand, the [bmim]+ ions acted as effective capping ions to preferentially stabilize the {100} facets. The obtained near‐monodisperse anatase TiO2 nanocuboids exhibited an interesting self‐assembly behavior during deposition. These single‐crystalline anatase nanocuboids showed extremely high crystalline phase stability, retaining the pure phase of anatase as well as the morphology even after being calcined at 900 °C. Moreover, the anatase nanocuboids exhibited considerably enhanced photocatalytic activity owing the wholly exposed active {100} and {001} facets.

One-Pot Synthesis of Regular Rhombic Titanium Dioxide Supracolloidal Submicrometer Sheet via Sol–Gel Method

“…According to the above mechanism, the two faces of a-SMSs should be stabilized with protecting agents such as acetonitrile; thus after calcination, these sites will be transformed into high photoactivity facets, as reported extensively. − HRTEM image showed that most lattice fringes are {101} facets, which suggests the exposed surface should be high photocatalytic activity facets, in agreement with the prediction based on the above mechanism. Therefore, photocatalytic activity higher than P25 would be expected.…”

One-Pot Synthesis of Regular Rhombic Titanium Dioxide Supracolloidal Submicrometer Sheet via Sol–Gel Method

“…According to the above mechanism, the two faces of a-SMSs should be stabilized with protecting agents such as acetonitrile; thus after calcination, these sites will be transformed into high photoactivity facets, as reported extensively. − HRTEM image showed that most lattice fringes are {101} facets, which suggests the exposed surface should be high photocatalytic activity facets, in agreement with the prediction based on the above mechanism. Therefore, photocatalytic activity higher than P25 would be expected.…”

Controlling Surface Defects and Photophysics in TiO2 Nanoparticles

“…Lattice planes were determined by analyzing the profile of the nanoparticles HRTEM images in Figure (profiles shown in SI). For both kinds of nanoparticles lattice planes of 1.6 ± 0.1 Å and 2.4 ± 0.1 Å were found, which matches the literature values of 1.6 and 2.4 Å reported for the (211) and (004) planes of tetragonal anatase. − Confirmation that anatase is the crystalline phase for both R-TiO 2 and L-TiO 2 nanoparticles was demonstrated by TEM results, EPR measurements, and UV–vis spectra ( vide infra). Such results are in agreement with the observations of Durupthy and co-workers who showed that anatase is the most stable phase for TiO 2 nanoparticles smaller than 14 nm …”

Enhancing photocatalytic CO2 reduction by coating an ultrathin Al2O3 layer on oxygen deficient TiO2 nanorods through atomic layer deposition

“…The surface quantitative elemental composition analysis (Fig.3b) shaped structure shown in Fig. 4a and 4c agrees well with the SEM observation and literature report 18,21,22 .…”

One-Pot Synthesis of Regular Rhombic Titanium Dioxide Supracolloidal Submicrometer Sheet via Sol–Gel Method

“…According to the above mechanism, the two faces of a-SMSs should be stabilized with protecting agents such as acetonitrile; thus after calcination, these sites will be transformed into high photoactivity facets, as reported extensively. − HRTEM image showed that most lattice fringes are {101} facets, which suggests the exposed surface should be high photocatalytic activity facets, in agreement with the prediction based on the above mechanism. Therefore, photocatalytic activity higher than P25 would be expected.…”

Controlling Surface Defects and Photophysics in TiO2 Nanoparticles

“…Lattice planes were determined by analyzing the profile of the nanoparticles HRTEM images in Figure (profiles shown in SI). For both kinds of nanoparticles lattice planes of 1.6 ± 0.1 Å and 2.4 ± 0.1 Å were found, which matches the literature values of 1.6 and 2.4 Å reported for the (211) and (004) planes of tetragonal anatase. − Confirmation that anatase is the crystalline phase for both R-TiO 2 and L-TiO 2 nanoparticles was demonstrated by TEM results, EPR measurements, and UV–vis spectra ( vide infra). Such results are in agreement with the observations of Durupthy and co-workers who showed that anatase is the most stable phase for TiO 2 nanoparticles smaller than 14 nm …”

Enhancing photocatalytic CO2 reduction by coating an ultrathin Al2O3 layer on oxygen deficient TiO2 nanorods through atomic layer deposition

“…The surface quantitative elemental composition analysis (Fig.3b) shaped structure shown in Fig. 4a and 4c agrees well with the SEM observation and literature report 18,21,22 .…”

One-Pot Synthesis of Regular Rhombic Titanium Dioxide Supracolloidal Submicrometer Sheet via Sol–Gel Method

“…According to the above mechanism, the two faces of a-SMSs should be stabilized with protecting agents such as acetonitrile; thus after calcination, these sites will be transformed into high photoactivity facets, as reported extensively. − HRTEM image showed that most lattice fringes are {101} facets, which suggests the exposed surface should be high photocatalytic activity facets, in agreement with the prediction based on the above mechanism. Therefore, photocatalytic activity higher than P25 would be expected.…”

Controlling Surface Defects and Photophysics in TiO2 Nanoparticles

“…Lattice planes were determined by analyzing the profile of the nanoparticles HRTEM images in Figure (profiles shown in SI). For both kinds of nanoparticles lattice planes of 1.6 ± 0.1 Å and 2.4 ± 0.1 Å were found, which matches the literature values of 1.6 and 2.4 Å reported for the (211) and (004) planes of tetragonal anatase. − Confirmation that anatase is the crystalline phase for both R-TiO 2 and L-TiO 2 nanoparticles was demonstrated by TEM results, EPR measurements, and UV–vis spectra ( vide infra). Such results are in agreement with the observations of Durupthy and co-workers who showed that anatase is the most stable phase for TiO 2 nanoparticles smaller than 14 nm …”

Enhancing photocatalytic CO2 reduction by coating an ultrathin Al2O3 layer on oxygen deficient TiO2 nanorods through atomic layer deposition

“…The surface quantitative elemental composition analysis (Fig.3b) shaped structure shown in Fig. 4a and 4c agrees well with the SEM observation and literature report 18,21,22 .…”