Modulation of the Surface Catalytic Activity of Boron-Doped Cobalt Oxide with Crystalline/Amorphous Interfaces for
Liang Zhao1, Sihao Zhi1, Chengchao Yu1
1State Key Laboratory of Integrated Optoelectronics, JLU Region, and College of Electronic Science and Engineering, Jilin University, Changchun 130012, P. R. China.
Abstract:
Enhancing the gas-solid interface interaction between sensing materials and O2 is promising for the development of high-performance metal oxide-based chemiresistive gas sensors. Nevertheless, high-performance gas sensors have not been developed owing to the lack of a deep understanding of the sensing mechanism with regards to gas-solid interface interactions. In this study, boron-doped cobalt oxide (B-Co3O4) with crystalline/amorphous interfaces was synthesized for acetone detection. The crystalline/amorphous interfaces reduce the valence of Co species (64.2% Co2+) and endow sensing materials with rich oxygen vacancies. The improvement of gas-solid interactions by modulating the d-band center (increase from -3.34 eV to -2.67 eV) level was innovatively developed by the novel in situ construction of crystalline/amorphous interfaces through a low-temperature annealing strategy, subsequently leading to improved acetone-sensing performance. Theoretical calculations and energy band structure analysis revealed that the construction of crystalline/amorphous interfaces led to an upshift in the d-band center of Co3O4 from -3.34 eV to -2.67 eV, which enhanced the interaction between Co 3d and O 2p, thus accelerating the interaction of BCo-225 and O2. Consequently, the BCo-225 sensor showed a high response (105.6-100 ppm acetone), a low limit of detection (20 ppb), excellent stability in 4 days (only 2.7% response fluctuation vs 46.2% changes for Co3O4-225), and good stability for 6 months (109.3 to100 ppm acetone). The present BCo-225 sensor outperforms acetone sensors based on metal oxides synthesized via high-temperature annealing and overcomes the poor stability of traditional amorphous sensing materials.
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