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

ZnO nanocrystals with three different morphologies have been synthesized via a simple sol-gel-based method using Brosimum parinarioides (bitter Amapa) and Parahancornia amapa (sweet Amapa) 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 (similar to 15.8 nm), teetotum-like (similar to 16.8 nm), and cambuci-like (similar to 22.2 nm) shapes for the samples synthesized using bitter Amapa, sweet Amapa, and bitter/sweet Amapa chelating agent, respectively. The band gap luminescence was observed at similar to 2.67-2.79 eV along with several structural defect-related, blue emissions at 468-474 nm (V-O, V-Zn, Zn-i), green emissions positioned at 513.89-515.89 (h-V-O(+)), and orange emission at 600.78 nm (V-O(+)-V-O(++)). 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 Amapa and sweet Amapa latex are effective chelating agents for synthesizing distinctive-shaped ZnO nanocrystals with highly defective and remarkable photocatalytic activity.