Metal oxide semiconductor-based heterojunctions synthesized by wet-chemical strategies for efficient volatile organic compounds detection

Abstract

Metal oxide semiconductor (MOS)-based chemiresistive sensors have been widely applied in indoor air quality detection, medical diagnostics, and environmental monitoring, and they also hold promise for future applications in agricultural product quality assessment. Developing sensitive materials with enhanced stability, humidity resistance, and high selectivity toward specific gases has become a key focus for their application in complex environments. Among these efforts, the construction of optimized heterostructures has gained significant attention and seen substantial progress in recent years, driven by advancements in material characterization techniques, electrochemical research, and the growing use of Density Functional Theory (DFT) calculations. Nevertheless, few reviews offer a comprehensive overview of heterostructure types and a clear explanation of their wet-chemical synthesis principles and sensitization mechanisms. Reviewing research papers published between 2020 and 2025, this work focuses on MOS-based composite materials constructed by various wet-chemical technologies for monitoring volatile organic compounds (VOCs). It categorizes three representative types of heterostructures—uniform distribution type, surface-loaded type, and core-shell type—based on the distribution of the second phases. It offers a comprehensive analysis and summary of the construction strategies for each configuration, the charge exchange between materials and gas molecules, electron transport within and between materials, and potential sensitization effects. On this basis, a comparative analysis identifies the key points for designing each configuration, the gaps in current research and achievements, and the potential focus for future investigation. This review aims to provide guidance for synthesizing highly efficient sensitized heterostructure materials.