Evaluation of the Photocatalytic Activity of Distinctive-Shaped ZnO Nanocrystals Synthesized Using Latex of Different Plants Native to the Amazon Rainforest

Abstract

ZnO nanocrystals with three different morphologies have been synthesized via a simple sol-gel-based method using Brosimum parinarioides (bitter Amapá) and Parahancornia amapa (sweet Amapá) latex as chelating agents. X-ray diffraction (XRD) and electron diffraction patterns (SAED) patterns showed the ZnO nanocrystals were a pure hexagonal wurtzite phase of ZnO. XRD-based spherical harmonics predictions and HRTEM images depicted that the nanocrystallites constitute pitanga-like (~15.8 nm), teetotum-like (~16.8 nm), and cambuci-like (~22.2 nm) shapes for the samples synthesized using bitter Amapá, sweet Amapá, and bitter/sweet Amapá chelating agent, respectively. The band gap luminescence was observed at ~2.67–2.79 eV along with several structural defect-related, blue emissions at 468–474 nm (VO, VZn, Zni), green emissions positioned at 513.89–515.89 (h-), and orange emission at 600.78 nm (–). The best MB dye removal efficiency (85%) was mainly ascribed to the unique shape and oxygen vacancy defects found in the teetotum-like ZnO nanocrystals. Thus, the bitter Amapá and sweet Amapá latex are effective chelating agents for synthesizing distinctive-shaped ZnO nanocrystals with highly defective and remarkable photocatalytic activity.

Insights into the Fe3+ Doping Effects on the Structure and Electron Distribution of Cr2O3 Nanoparticles

“…These crystallites tend to present a pitanga-like shape, which is a common growth feature. Similar behavior has been observed previously for ZnO nanocrystals [ 81 ]. However, it is worth mentioning that the relation between the crystallite size and the concentration of the defects was remarkable for the sample with x = 0.12, suggesting that the Fe content increasing up to this value induces an increase in the symmetry of the surface atoms or decreases the number of unsaturated surface states of Cr 3+ /Fe 3+ .…”

Ceramic ZnO-SnO2-Fe2O3 Powders and Coatings -Effective Photogenerators of Reactive Oxygen Species

“…Photocatalytic materials are used in many different practical applications (water and air purification, sensors, water splitting, etc.) and are the object of intensive investigations [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Many oxide semiconductor materials are effective photocatalysts, demonstrate antibacterial activity and have an excellent thermal stability and chemical durability.…”

“…Ceramic materials (powders and coatings) based on ZnO are very effective photocatalysts [2][3][4][5][6][7][8][9][10][11][12][13][14] which have been successfully tested in industrial conditions [1]. Modification of the ZnO ceramic materials using other oxides additions provides a significant enhancement to its photocatalytic and bactericidal characteristics [3][4][5][6][7][8]. These additions decrease the size of ZnO crystals, modify the crystal structure and morphology of the ZnO ceramic materials and increase their specific surface areas.…”

“…The application of these semiconductor heterostructures allows to decrease the possibility of the recombination of photogenerated electron-hole pairs by the spatial separation of charges. It was found that the application of different heterostructures (ZnO-SnO 2 [3,4]; ZnO-Fe 2 O 3 [6]; ZnO-TiO 2 [5]) provides the increase in the effectiveness of photocatalysis [3][4][5][6].…”

“…Therefore, besides the difference in the thickness of photocatalytic layers between thin ceramic coating and powder, the features of crystal structures and morphologies of these ceramics can have an influence on their photocatalytic properties. In spite of small thickness, ceramic coatings demonstrate photocatalytic properties [4,5,14,20,[29][30][31][32], although in some cases the photocatalysis rate is low [31].…”