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.