Rutile-Coated B-Phase TiO₂ Heterojunction Nanobelts for Photocatalytic H₂ Evolution

Abstract

In the field of photocatalysis, the crystal phase engineering of titanium dioxide is a research hotspot. Titanium dioxide heterojunctions often exhibit better photocatalytic performance than single-phase TiO2. Here, a two-step hydrothermal and calcination method is used to build the phase interface between TiO2 (B) and rutile for the first time, and a narrow band gap heterojunction TiO2 material is synthesized. The heterojunction TiO2 material is characterized by transmission electron microscopy (TEM), ultraviolet (UV), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR). The two phases are connected by a corner-sharing at the phase interface. The different positions of the conduction bands and valence bands between the two phases result in the effective separation of photogenerated electrons and holes through the phase interface. Under light, the photogenerated holes are transferred to the rutile phase and quickly consumed by the sacrificial agent, and the surplus photogenerated electrons participate in the H2 evolution reaction. When the ratio of TiO2 (B) to rutile is about 2/1, the TiO2 (B)/rutile heterojunction exhibits the highest photocurrent and the best H2 evolution performance under the present experimental conditions.

Photocatalytic hydrogen evolution over Pt–Pd dual atom sites anchored on TiO2 nanosheets

“…14 and 15)) as photocatalysts, titanium dioxide (TiO 2 ) is considered to be the most suitable photocatalyst for hydrogen production via water splitting due to its low cost, nontoxicity, high catalytic selectivity, and long-term photostability. 16 However, the solar-hydrogen conversion performance of TiO 2 -based photocatalysts remains unsatisfactory because of their low light utilization and the rapid recombination of charge carriers. 17 To overcome these drawbacks, numerous studies have attempted to make solar energy conversion more efficient.…”

Construction of the Rutile/Anatase Micro-Heterophase Junction Photocatalyst from Anatase by Liquid Nitrogen Quenching Method

“…However, with the treatment time above 120 min, the signals at g = 2.003 and 1.973 also become weak. It may be due to the fact that with a further increase in the rutile content, the heterophase interface would move inward, and the charge carriers separated from the interface may be more likely to recombine on the way to the surface . Consequently, the concentration of electrons trapped at oxygen vacancies would decrease and meanwhile the concentration of transferred electrons to Ti 4+ sites would also reduce.…”

“…The reason may be that with more rutile phase on the surface, the heterophase interface may move inward and the charge carriers separating through the phase interface may be far away from the surface and become more vulnerable to recombination on the way to the surface. 25 In a word, the above results indicate that in addition to the rutile/ anatase TiO 2 micro-heterophase junction with a large BET surface area structurally, the interaction between anatase and rutile TiO 2 also results in the evidently enhanced photocatalytic activity of RQ-120.…”

“…It may be due to the fact that with a further increase in the rutile content, the heterophase interface would move inward, and the charge carriers separated from the interface may be more likely to recombine on the way to the surface. 25 Consequently, the concentration of electrons trapped at oxygen vacancies would decrease and meanwhile the concentration of transferred electrons to Ti 4+ sites would also reduce. This decrease in the signal of oxygen vacancies and Ti 3+ also coincides with the decreased hydrogen production rates for RQ-TiO 2 samples with longer RQ times mentioned previously.…”

Hierarchically Porous, Biphasic, and C-Doped TiO2 for Solar Photocatalytic Degradation of Dyes and Selective Oxidation of Benzyl Alcohol

“…TiO 2 photocatalysts have been of interest, as they facilitate the photocatalytic degradation of organic pollutants, − selective organic transformations, − and hydrogen generation by photocatalytic water splitting. − Adsorbed radicals formed by photogenerated electron–hole pairs at the photocatalyst surface cause photocatalytic reactions. , TiO 2 exists in three polymorphic formsanatase, rutile, and brookite. ,, The anatase phase has been found to exhibit higher photocatalytic efficiency. , While anatase with a band gap of 3.2 eV is confined to absorption of UV light, rutile with a lower band gap (3.0 eV) can absorb visible light. However, low surface area, low redox potential, and faster electron–hole recombination render rutile ineffective .…”