Shape-Dependent Charge Transfers in Crystalline ZnO Photocatalysts: Rods versus Plates

Abstract

ZnO particles with rod and plate configurations were synthesized using a solvothermal method using zinc acetate and zinc chloride, respectively. The surface of the as-synthesized ZnO rods and plates were characterized using various analysis tools (XRD, XPS, photoluminescence, FE-SEM, HR-TEM, BET, and UV− vis) and their photocatalytic activities were examined for six different redox reactions. The surface areas and bandgaps of the two ZnO samples were nearly identical; however, XPS and photoluminescence (PL) studies showed that the rods and the plates have relatively pronounced oxygen vacancy and oxygen interstitial contributions, respectively. ZnO rods were found to be active for the decomposition of methylene blue and phenol, the production of OH radicals, and the generation of photocurrents, all of which are associated with single-electron transfer reactions. On the other hand, ZnO plates were more effective for the production of molecular hydrogen and hydrogen peroxide, both of which are initiated by two-electron transfer reactions. These single versus multiple charge transfers are discussed with regard to the roles of oxygen vacancies and oxygen interstitials, which are located near the conduction and the valence bands, respectively.

ZnO nanorods prepared via ablation of Zn with millisecond laser in liquid media

“…[0001] direction [26,28,[37][38][39][40]. When the applied laser conditions allowed for a certain temperature raise, caused by target heating, nanostructures with similar sizes and shapes were observed (see Fig.2.g, the data for products prepared at 1kW and 2 ms, 5kW and pulse widths longer than 1 ms).…”

The Applications of Morphology Controlled ZnO in Catalysis

“…Jeong et al also compared the photo-catalytic performance of ZnO nanorods and nanoplates [179]. On the contrary, they discovered that ZnO nanorods were more active for the degradation of phenol and MB, and the generation of OH· radicals and photocurrents.…”

“…Flower-like interwoven grown ZnO nano-sheets and un-aggregated nanosheets were prepared and tested for photo-degradation of MB. The excellent photo-degradation efficiencies Jeong et al also compared the photo-catalytic performance of ZnO nanorods and nanoplates [179]. On the contrary, they discovered that ZnO nanorods were more active for the degradation of phenol and MB, and the generation of OH• radicals and photocurrents.…”

Microstructure, wettability and electrical properties of n-ZnO/ZnO-SL/p-Cu2O heterojunction

“…In our case, the green-yellow emission band may be come from the common contribution of oxygen vacancy (V O ? ) [22] and interstitial oxygen (O i -) [23].…”