Study on Effect of [OH−] Linkages on Physical, Electrical, and Gas Sensing Properties of ZnO Nanoparticles

This paper reports the growth mechanism of sol-gel derived nanocrystalline ZnO powder. The influence of pH value on the particle size and its properties are studied using X-ray diffraction, UV, Fourier transform infrared spectroscopy, photoluminescence (PL), and impedance spectroscopy. UV analysis reveals an increase in bandgap due to decrease in particle size. The strong UV emission along with some defect sites is also observed from PL spectra. The presence of Zn-OH linkages are observed in the case of ZnO with lower pH values (pH 7, 8, and 9) which are responsible for lower sensitivity toward volatile organic compounds. However, higher pH values (pH 10 and 11) have absence of Zn-OH linkage, which improves the gas sensing performance.