Synthesis of Ti4O7/Ti3O5 Dual-Phase Nanofibers with Coherent Interface for Oxygen Reduction Reaction Electrocatalysts

Abstract

Electrocatalysts play an important role in oxygen reduction reaction (ORR) in promoting the reaction process. Although commercial Pt/C exhibits excellent performance in ORR, the low duration, high cost, and poor methanol tolerance seriously restrict its sustainable development and application. TinO2n−1 (3 ≤ n ≤ 10) is a series of titanium sub-oxide materials with excellent electrical conductivity, electrochemical activity, and stability, which have been widely applied in the field of energy storage and catalysis. Herein, we design and synthesize Ti4O7/Ti3O5 (T4/T3) dual-phase nanofibers with excellent ORR catalytic performance through hydrothermal growth, which is followed by a precisely controlled calcination process. The H2Ti3O7 precursor with uniform size can be first obtained by optimizing the hydrothermal growth parameters. By precisely controlling the amount of reducing agent, calcination temperature, and holding time, the T4/T3 dual-phase nanofibers with uniform morphology and coherent interfaces can be obtained. The orientation relationships between T4 and T3 are confirmed to be [ 001 ] T 3 / / [ 031 ] T 4 , ( 100 ) T 3 / / ( 92 6 ¯ ) T 4 , and ( 010 ) T 3 / / ( 1 2 ¯ 6 ) T 4 , respectively, based on comprehensive transmission electron microscopy (TEM) investigations. Furthermore, such dual-phase nanofibers exhibit the onset potential and half-wave potential of 0.90 V and 0.75 V as the ORR electrocatalysts in alkaline media, respectively, which illustrates the excellent ORR catalytic performance. The rotating ring-disk electrode (RRDE) experiment confirmed the electron transfer number of 3.0 for such catalysts, which indicates a mixture of two electron and four electron transfer reaction pathways. Moreover, the methanol tolerance and cycling stability of the catalysts are also investigated accordingly.

Formation Mechanism of Nitrogen-Doped Titanium Monoxide Nanospheres and Their Application as Sulfur Hosts in Lithium Sulfur Batteries

“…In addition, the diameter of the nanospheres has decreased to around 210 nm, which suggests the excellent physical confinement effect of PDA coatings during the calcination process. Such effects have also been confirmed in our previous research works. − In comparison, the product without the PDA coating has completely lost its spherical morphology, as shown in Figure S3. Through the TEM bright field (BF) and HRTEM images in Figure c,d, it is found that the nanospheres are accumulated by a large number of small particles.…”

Systematic Study of Effective Hydrothermal Synthesis to Fabricate Nb-Incorporated TiO2 for Oxygen Reduction Reaction

“…The value of E ORR was very similar to the reference value (0.7 V); however, the value of i ORR for the 0 MPa samples synthesized in this study was 10 times higher than the reference value. It can be assumed that the obtained amount of TiO 2-x with electron transfer properties, particularly Ti 4 O 7 with high conductivity [24,49,50], was suppressed under this synthetic process owing to the Kirkendall effect (Figure 5); therefore, the value of i ORR at 0 MPa decreased. The oxygen vacancies, which contribute toward the electrical transfer ability in oxides, decreased according to the pressure; therefore, it is necessary to further study this issue to perform this experiment at low temperatures.…”

Synthesis of dual-phase Ti3O5/Ti4O7 nanofibers for efficient adsorption of SARS-CoV-2

“…The Ti 3 O 5 /Ti 4 O 7 nanofibers were synthesized using the Shi’s hydrothermal method with modification [12] . Briefly, 20 mL NaOH solution (containing 12 g NaOH in dH 2 O) and 8 mL Ti(SO 4 ) 2 solution (containing 1.07 g Ti(SO 4 ) 2 in dH 2 O) were mixed by magnetic stirring.…”