Effect of PEO molecular weight on sunlight induced photocatalytic activity of ZnO/PEO composites

Surfactant-assisted microwave processing of ZnO particles: a simple way for designing the surface-to-bulk defect ratio and improving photo(electro)catalytic properties

“…To vary the concentration and the type of point defects, we used polyethylene oxide (PEO) with different molecular weights (200 000, 600 000 and 900 000 g mol À1 ). 30 We demonstrated that oxygen interstitials at the surface of ZnO particles had profound effects on the direct sunlight photodegradation of methylene blue. The aim of this research is to in situ modify the surface-to-bulk defects ratio in ZnO particles by surfactant-directed microwave processing.…”

“…34 We demonstrated that a relatively small amount of surfactants inuenced the crystallite size and polarity despite the short time period (5 min) of microwave irradiation, leading to a fast crystallization of the Zn(OH) 2 precursor into the ZnO phase. 30 The representative FE-SEM micrographs of MW processed zinc oxide particles are shown in Fig. 2.…”

“…The most intensive band at 98 cm À1 , assigned as E 2L , is characteristic of the wurtzite crystal structure and can be attributed to vibrations of the zinc sublattice in ZnO. 30,53,54 The low intensity peak centered near 200 cm À1 and a sharp peak at 327 cm À1 are attributed to the second-order phonon mode 2E 2L and the multi phonon mode E 2H -E 2L , respectively. 55 The weak shoulder near 380 cm À1 (marked with a dark cyan triangle in Fig.…”

“…Different approaches have been developed for enhancing the optical properties of ZnO materials: incorporation of transition metal ions into the crystal structure, sensitization of particle surface, hydrogenation, incorporation of crystalline defects in metal oxide semiconductors in the form of vacancies and interstitials, etc. 9,[27][28][29][30] Crystalline defects can strongly inuence electrical and optical properties of a semiconductor. Defects oen introduce levels in the band gap of semiconductors; 31 these levels involve transitions between different charge states of the same defect.…”

Molecular designing of nanoparticles and functional materials

“…We studied the influence of poly(ethylene oxide) (PEO) molecular weight on the photocatalytic activity of ZnO/PEO nanostructured composites. 23 Microwave processing was used to prepare ZnO nanoparticles with a high density of intrinsic crystal defects responsible for visible light absorption and enhanced photocatalytic efficiency. To further enhance the photocatalytic activity of ZnO nanoparticles, oxygen interstices were supplied via a composite with PEO.…”