| Summary: | The application of BaF<sub>2</sub>-modified <i>h</i>BN flakes as rapid response and recovery as well as sensitive chemoresistive sensing device materials for detection of acetone and/or ethanol is presented in this study. Modification of the <i>h</i>BN flakes was achieved by using the modified polymer derived ceramics (PDCs) process through the use of 0–10 wt% BaF<sub>2</sub> and 5 wt% Li<sub>3</sub>N. Upon exposure to individual acetone and ethanol vapours, room temperature sensing studies revealed high LoD values (−144–460 ppm<sub>acetone</sub> and −134–543 ppm<sub>ethanol</sub>) with extremely compromised sensitivities of −0.042–0.72 × 10<sup>−2</sup> ppm<sup>−1</sup><sub>acetone</sub> and −0.045–0.19 × 10<sup>−2</sup> ppm<sup>−1</sup><sub>ethanol</sub> for the structurally improved 5–10 wt% BaF<sub>2</sub>-modified <i>h</i>BN flakes. Moreover, enhanced sensing for 0–2.5 wt% BaF<sub>2</sub>-modified <i>h</i>BN flakes, as shown by the low LoDs (−43–86 ppm<sub>acetone</sub> and −30–62 ppm<sub>ethanol</sub>) and the high sensitivities (−1.8–2.1 × 10<sup>−2</sup> ppm<sup>−1</sup><sub>acetone</sub> and −1.5–1.6 × 10<sup>−2</sup> ppm<sup>−1</sup><sub>ethanol</sub>), was attributed to the presence of defects subsequently providing an abundance of adsorption sites. Overall, the study demonstrated the importance of structural properties of <i>h</i>BN flakes on their surface chemistry towards room temperature selective and sensitive detection of VOCs.
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