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<p>Developing highly sensitive gas sensors operating at low temperatures remains a significant challenge. Herein, we propose a synergistic strategy combining surface heterojunction engineering and deep-UV photo-activation to achieve enhanced ethanol sensing performance. Novel ZnO/ZnFe<sub>2</sub>O<sub>4</sub> heterostructures were successfully fabricated via a facile solvothermal surface-decoration method. Structural and morphological analyses reveal the uniform distribution of ultrafine, superparamagnetic ZnFe<sub>2</sub>O<sub>4</sub> nanocrystals (6–21&#xa0;nm) onto pristine ZnO base particles, forming an exposed type-II heterojunction architecture. Gas sensing evaluations demonstrate that under 254&#xa0;nm UV irradiation, the optimal ZnO:ZF-1 heterostructure exhibits a high response of ~ 72 to 0.47% ethanol at a reduced operating temperature of 180&#xa0;°C. This performance is significantly higher than the pristine ZnO sensor operating in the dark, which achieves a maximum response of only ~ 20 at a high temperature of 300&#xa0;°C. Furthermore, the photo-activated sensor demonstrates good selectivity against various interfering volatile organic compounds and gases, and excellent cyclic stability. The underlying sensing mechanism is comprehensively elucidated: the built-in electric field at the type-II interface effectively suppresses the recombination of photogenerated electron–hole pairs—as supported by pronounced photoluminescence quenching. This effective charge separation facilitates the transfer of active electrons to the sensor surface, promoting the generation of reactive photo-induced oxygen species that facilitate the oxidation of ethanol molecules. This study provides useful insights for the design of photo-activated heterojunction-based gas sensors operating at reduced temperatures.</p>

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Deep-UV activated ZnO/ZnFe2O4 surface heterojunctions for enhanced low-temperature ethanol sensing

  • 期刊论文

  • 发表日期：

    2026年7月1日

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  • Nguyen Minh Vuong,
  • Tran Ngoc Trung,
  • Nguyen Van Nghia

摘要

Developing highly sensitive gas sensors operating at low temperatures remains a significant challenge. Herein, we propose a synergistic strategy combining surface heterojunction engineering and deep-UV photo-activation to achieve enhanced ethanol sensing performance. Novel ZnO/ZnFe2O4 heterostructures were successfully fabricated via a facile solvothermal surface-decoration method. Structural and morphological analyses reveal the uniform distribution of ultrafine, superparamagnetic ZnFe2O4 nanocrystals (6–21 nm) onto pristine ZnO base particles, forming an exposed type-II heterojunction architecture. Gas sensing evaluations demonstrate that under 254 nm UV irradiation, the optimal ZnO:ZF-1 heterostructure exhibits a high response of ~ 72 to 0.47% ethanol at a reduced operating temperature of 180 °C. This performance is significantly higher than the pristine ZnO sensor operating in the dark, which achieves a maximum response of only ~ 20 at a high temperature of 300 °C. Furthermore, the photo-activated sensor demonstrates good selectivity against various interfering volatile organic compounds and gases, and excellent cyclic stability. The underlying sensing mechanism is comprehensively elucidated: the built-in electric field at the type-II interface effectively suppresses the recombination of photogenerated electron–hole pairs—as supported by pronounced photoluminescence quenching. This effective charge separation facilitates the transfer of active electrons to the sensor surface, promoting the generation of reactive photo-induced oxygen species that facilitate the oxidation of ethanol molecules. This study provides useful insights for the design of photo-activated heterojunction-based gas sensors operating at reduced temperatures.