Mechanistic Investigation of Enhancing ZnO Gas-Sensing Performance through Manganese Doping and Heterostructure Construction: A Combined Theoretical and Experimental Approach.

As a metal oxide semiconductor gas sensor, zinc oxide (ZnO) has garnered significant attention due to its potential for detecting toxic gases. While early studies have proposed mechanisms for enhancing ZnO gas-sensing performance, such as increased surface reactivity or defect sites induced by doping, detailed mechanistic models and in-depth analyses remain lacking. In this study, we first propose and model a multifunctional material surface by doping manganese atoms into ZnO (Mn@ZnO) and constructing heterojunctions (MnO/ZnO), resulting in the formation of a multifunctional surface material, Mn@ZnO||MnO/ZnO. Using density functional theory (DFT), we investigated the gas-sensing enhancement mechanisms of this material, analyzing factors such as adsorption energy, density of states, interlayer distances, charge transfer, and electrostatic potential, while also considering the influence of environmental oxygen. The theoretical results indicate that the introduction of manganese atoms and the formation of heterostructures significantly promoted the adsorption of gas molecules, particularly polar gases, transitioning from physical adsorption to chemisorption. Subsequently, based on these theoretical findings, we synthesized Mn@ZnO||MnO/ZnO using a simple one-step solution method. Experimental results demonstrated a substantial enhancement in the gas-sensing performance for polar gas molecules (such as CHO, CHCHOH, etc.), exhibiting exceptional sensitivity and selectivity, which were in strong agreement with the theoretical predictions. These results provide valuable insights for the future design and optimization of advanced sensing materials.