Probing the Challenge of P-Type Semiconductors in Long-Chain VOC Detection: 3D Micro-Flower Zinc Cobaltate Heterojunction Sensors.

Tetradecane, a long-chain alkane recently recognized as a volatile marker for early-stage mildew detection in stored grains and as a reference material in hydrocarbon studies, presents significant challenges for detection due to its inherent low reactivity and substantial molecular size. This study reports the synthesis of a microflower-like Fe@WO/ ZnCoO heterostructure for effective tetradecane sensing. The Fe@WO/ ZnCoO n-p junctions demonstrated significant alterations in electrical conductivity upon exposure to tetradecane at room temperature. The sensor achieved a reasonable detection limit of 78.4 ppb and a rapid recovery time of 36 s. The remarkable sensing performance is attributed to the synergistic interactions among multiple heterojunction interfaces, doping-induced active sites, the presence of oxygen vacancies, high-energy crystallographic facets, reduced grain size, and enhanced crystallinity, as supported by density functional theory calculations and molecular dynamics simulations. This work identifies a promising candidate for the detection of distinct volatile organic compounds, warranting further exploration in agricultural and emission monitoring applications while addressing a critical gap in metal oxide semiconductor sensors for the detection of large-molecule gases.