Acetone detection at reduced temperatures: Engineering Cl-doped ZnO nanodisks for enhanced gas-sensing performance

Abstract

This study presents the development of a groundbreaking acetone gas sensor leveraging Cl-doped ZnO nanodisks, designed to operate efficiently at low temperatures. Through comprehensive experimental and theoretical analyses, they have elucidated the exceptional sensing capabilities of Cl-doped ZnO nanodisks. Both undoped and Cl-doped ZnO with varying chlorine concentrations were synthesized on Si/SiO₂ substrates using a straightforward thermal evaporation method in a tube furnace. Notably, the morphology of pure ZnO formed microdisks, whereas the Cl-doped ZnO transitioned to nanodisks, and with increased Cl doping, it further evolved into nanoplates. X-ray diffraction and x-ray photoelectron spectroscopy (XPS) confirmed the successful substitution of oxygen ions with chlorine ions. Enhanced photoluminescence and XPS analyses revealed that Cl-doped ZnO contained a significantly higher density of oxygen vacancies compared to undoped ZnO. The Cl-doped ZnO sensor exhibited an outstanding sensitivity of approximately 40 and an impressive selectivity of 55% toward 100 ppm acetone at 80°C. Cl doping markedly improved the sensor's response and recovery times, enabling the detection of acetone at concentrations as low as 225 ppb at 80°C—a remarkable achievement unattainable with pure ZnO. All characterization results strongly indicate that oxygen vacancies play a pivotal role in enhancing the gas-sensing performance of Cl-doped ZnO nanodisks. Cutting-edge density functional theory calculations uncovered significant interactions between acetone and Cl-doped ZnO through charge density variations and band structure analysis. These interactions resulted in notable changes in the density of states, including a distinct peak near −3 eV, indicating enhanced sensitivity.