Precursor Selection for Efficient Synthesis of ZnO Rods Through Direct Heating Method

ABSTRACT This study explores the direct heating (DH) method for synthesizing and immobilizing zinc oxide (ZnO) rods on substrates, highlighting issues like ZnO particles depositing on rods and incomplete substrate coverage. These particles can cause secondary pollution in water systems if not adequately managed. The study tested three precursor solutions to improve ZnO rod synthesis: Precursor A (zinc acetate dihydrate and sodium hydroxide), Precursor B (zinc nitrate hexahydrate and ammonia), and Precursor C (zinc nitrate hexahydrate and hexamethylenetetramine). Under the synthesis conditions of 40 W heating power for 4 min, Precursor A was found to be most effective, producing ZnO rods with minimal particle deposition and 100% surface coverage. The ZnO rods had an average diameter of 201.4 ± 58.9 nm and an areal density of 17 ± 2 rods/µm 2 , achieving removal efficiencies of 25.15% for rhodamine B (RhB) and 25.50% for copper ions, thereby demonstrating the potential of the DH method for efficient ZnO rod synthesis. These results underscore the potential of the DH method as a promising approach for the large‐scale immobilization of ZnO on Kanthal coils, offering scalability and suitability for industrial‐scale production of ZnO rods.