ABSTRACT
It is well known that the lattice structure for a crystal can be manipulated through mechanical strain, temperature, an electric field, a magnetic field, and light. In the past, the photostriction commonly occurs at the surface and the bulk photostriction is very small in most semiconductors. Here, the 532 nm laser can excite the excess electron-hole pairs in the surface layer and consequently these carriers diffuse in the millimeter-thick MAPbBr3-xIx crystal and introduce a giant bulk photostriction of 0.17, 0.28, and 0.35% for the 0.5 mm-thick MAPbBr3-xIx single crystals at x = 0, 1, and 2, respectively. Furthermore, the displacement of each crystal linearly increases from hundreds of picometers to several micrometers when the light intensity increases from about 0.2 to 536 mW/cm2. Since both the maximum strain and the displacement accuracy are as good as those of PZT ceramics used in piezoelectric actuators, these crystals can be used in light-driven actuators for precise positioning.
ABSTRACT
BiOBr/regenerated cellulose composites photocatalysts were easily prepared by in situ synthesis method with the utilization of pulp board as the cellulose source in TEMPO (2, 2, 6, 6-tetramethylpiperidine-1-oxyl radical)-Mediated Oxidation. The physicochemical characteristic of the BiOBr/cellulose composites are systematically indicated by SEM, XRD, FT-IR, TG, BET, XPS, UV-vis, TOC, HPLC and EIS. The results indicated that the BiOBr nanoparticles were incorporated into cellulose surface, and there was a strong interaction between the hydroxyl groups of regenerated cellulose (RC) and the BiOBr through hydrogen bonding interactions. Under visible light irradiation, the composites showed remarkable photocatalytic activity for degradation of Rhodamine B (C0â¯=â¯25â¯mgâ¯L-1) with degradation percentage of 99% within only 50â¯min irradiation and 88.6% after four recycles. This study promotes that the BiOBr/cellulose composites can act as a new and green portable photocatalyst in the field of wastewater treatment.