RESUMEN
Charge recombination severely restricts the photocatalytic efficiencies of materials. Loading cocatalysts on the surface of host photocatalysts is a promising strategy for charge separation, which, however, suffers from the large Schottky barrier at the cocatalyst/host interface. Herein, a series of Pt/PbTiO3 compounds were constructed as a proof-of-concept utilizing the piezoelectric field of PbTiO3 under acoustic vibrations to modulate the height of the interfacial Schottky barrier. These hybrid systems achieved highly efficient piezo-photocatalytic H2 evolution under simultaneous ultrasonication and light illumination. The manipulation of the height of the Schottky barrier by the piezoelectric effect was validated by the I-V characteristics collected from conductive AFM. It is proposed that the acoustic-wave-induced piezoelectric field increased the electron flow from PbTiO3 to Pt over the modulated Schottky barrier, which promoted the spatial separation of photo-generated charge carriers and consequently enhanced the H2 evolution. These findings will extend the fundamental understanding of the synergistic piezo-photocatalysis mechanism and provide a new opportunity toward the rational design of novel materials systems for clean energy conversion.
RESUMEN
Ultrathin semiconductors have been proposed as an excellent platform to promote solar conversion due to their ultra-large specific surface area and unique surface structures. So far, the researchers designed and constructed some multi-component heterostructure photocatalysts, but they are still unable to avoid the recombination of photoexcited electron-hole pairs. This study introduces a built-in electric field in a one-component nanosheet to promote photo-generated carrier separation. For this reason, CdS nanosheets with both photocatalytic and piezoelectric properties were selected as research objects. The combination of these two properties renders CdS an excellent candidate for efficiently utilizing both light and vibrational energy for photocatalytic water splitting, without the need for coupling it to other materials or using an external bias. The result shows that the photocatalytic and piezoelectric coupling effect of CdS can make hydrogen production reach 633 µL h-1, which was more than twice the superposition of light and vibration. The development of this coupling effect contributes to the application of green energies, such as the use of natural sunlight and noise or vibration.
RESUMEN
Combining with carbon materials is a common and efficient strategy to improve the photocatalytic performance of TiO2. But the fundamental nature of the interfacial microstructures between carbon and TiO2 and how they affect the photocatalysis process remain controversial. In this work, hybrid TiO2@C nanocomposites with different carbon contents are synthesized. It is found that an interfacial disorder region with interfacial Ti-O-C bonds and abundant defects (oxygen vacancies, VO) can be generally formed from the chemical interactions between carbon and Ti-O-Ti skeletons. These interfacial VO sites are well stabilized by the carbon complex coating, and maintain their intrinsic nature in visible light absorption and electron trapping. Moreover, the synergistic effect of interfacial bonding, defective sites and the components on the visible photocatalysis of TiO2@C composites has been carefully investigated, and a corresponding mechanism is also proposed.
RESUMEN
TiO(2) bilayer films with a normal surface (Ns-TiO(2)), surface defects (Sd-TiO(2)), and interface defects (Id-TiO(2)) were successfully prepared by a combination of cold plasma treatment (CPT) and sol-gel dip-coating technology. The photodegradation of rhodamine B (RhB) over these as-prepared TiO(2) films was investigated via UV-vis irradiation. Results indicate that the three kinds of films exhibit very different photodegradation processes for RhB. A mainly N-deethylation reaction over the Ns-TiO(2) films, whereas an efficient degradation (cycloreversion) of RhB occurs over the Sd-TiO(2) films. In the RhB/Id-TiO(2) system, however, efficient N-deethylation concomitant with the highly efficient cycloreversion of RhB is observed. The efficiency of the complete mineralization of RhB dye follows the order of Id-TiO(2) > Sd-TiO(2) > Ns-TiO(2). It is proposed that the defect sites at the surface or the interface of TiO(2) films promote the separation of photogenerated electron-holes, leading to a higher photoactivity of defective TiO(2) films. Moreover, the higher stability over Id-TiO(2) as compared to Sd-TiO(2) indicates that the interface defect sites in TiO(2) could be applied in environmental photocatalysis.