Dual role of activated carbon as fuel and template for solution combustion synthesis of porous zinc oxide powders

Abstract In this work, nanosized zinc oxide (ZnO) powders were fabricated by urea–nitrate solution combustion synthesis using activated carbon as a structure‐directing template and secondary fuel at different fuel–oxidant ratios. The as‐synthesized powders were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N 2 adsorption–desorption measurements, UV–Vis diffuse reflectance spectroscopy, and photoluminescence. The effect of fuel amount on photocatalytic activity of ZnO powders was evaluated by the degradation of an azo dye Orange G. It was observed that combustion synthesis with activated carbon as a secondary fuel had a profound effect on reducing crystallite size and enhancement of specific surface area. The crystallite size of the as‐synthesized powders varied from 46 to 26 nm. The ZnO powder prepared at a fuel–oxidant ratio of 1.8 possessed the small crystallite size and high specific surface area of 69 m 2 /g. It correspondingly resulted in the highest dye removal percentage of 99% with a rate constant of 0.027 min −1 . The improvement in dye degradation can be due to the synergistic interaction and interplay of enhanced surface area and catalytic ability of the photocatalyst. This study provides a simple single‐step synthesis methodology to produce metal oxide nanopowders with tunable surface properties for high potential applications in catalysis, optoelectronics, and gas sensors.