First Principles Based Study On Sensing Mechanism Of Acetone Adsorption Of Co₃O₄

Acetone is a volatile organic compound that can cause damage to the human respiratory system.Whether from the perspective of environmental health or human health,efficient monitoring of acetone is essential.The chemical resistance sensor has the advantages of simplicity,high efficiency and low cost in detecting the gas direction.Many metal oxides have been proven to be able to efficiently detect acetone.At present,there are many researches on the detection of Co₃O₄ and its derivatives for acetone.However,these reports mostly focus on the experimental aspects but do not deeply analyze the sensing mechanism.In this paper,density functional theory is used to calculate the adsorption properties of Co₃O₄（111）,Mn-Co₃O₄（111）and W-Co₃O₄（111）to acetone,and analyze the adsorption mechanism of acetone from theoretical perspective.（1）Firstly,the mechanism of acetone adsorbed on Co₃O₄（111）surface has been studied.There may be five kinds of structures on Co₃O₄（111）surface.The configuration with the lowest energy is the most stable.By analyzing the surface structure,it can be found that there are two kinds of acetone adsorption sites on Co₃O₄（111）surface,namely Co²⁺and Co³⁺.By analyzing the adsorption properties such as adsorption energy,adsorption distance and transferred electrons,it can be found that acetone is chemically adsorbed on Co₃O₄（111）surface.Density of states analysis and charge distribution analysis can further confirm the conclusion.These results are consistent with the experimental results,indicating that Co₃O₄can be used as a potential material for acetone detection.（2）Then,the influence of Mn doping on the performance of Co₃O₄ for acetone detection has been studied.After optimizing structure,Mn atom has been found to be perpendicular to Co₃O₄（111）surface and bond with central oxygen.Compared with clean Co₃O₄（111）surface,although the adsorption capacity of the original adsorption sites decreased slightly,the new Mn²⁺sites had better adsorption capacity for acetone.In addition,the doping of Mn atom reduces the energy gap of Co₃O₄（111）surface and improves its sensitivity.As for selectivity,it decreases slightly because the best adsorption site on Mn-Co₃O₄（111）surface is still Co³⁺site.（3）Finally,the reason that modified W atom improve the adsorption capacity of Co₃O₄（111）surface toward acetone has been studied.The W atom on the surface of W-Co₃O₄（111）is adjacent to the Co²⁺site and bridges with three oxygen atoms.Similar to Mn-Co₃O₄,the adsorption ability of the original adsorption sites for acetone decreased slightly.However,the adsorption performance of the new W site for acetone is much superior than that of other sites.In addition,the modification of W atom is better than Mn site in shortening the band gap.In terms of selectivity,W-Co₃O₄（111）shows much higher adsorption capacity for acetone than that for methanol and ethanol due to W site of the best adsorption site for acetone.The study is universal and provides a theoretical basis for finding better modified p-type semiconductor sensors toward acetone.