Ni1-xZnxFe2O4 heterojunction composites derived from normal/inverse spinel structure for ppb-level acetone detection

To achieve non-invasive diabetes diagnosis through breath analysis, it is of great significance to construct a metal oxide acetone gas sensor with high sensitivity, selectivity and a low detection limit. Utilizing spinel ferrite materials with matching crystal structures to form high-quality heterojunctions can significantly enhance metal oxide sensing performance. Herein, a feasible strategy for constructing heterojunction composites using lattice-matched metal oxides, specifically inverse spinel NiFe 2 O 4 and normal spinel ZnFe 2 O 4 , was proposed to enhance the catalytic activity of acetone oxidation. By substituting Zn into NiFe 2 O 4 at the A-site and adjusting the Ni/Zn molar ratio, the synergistic effect of the heterojunction could be successfully implemented to enhance the detection of acetone. Notably, the optimal Ni 0.6 Zn 0.4 Fe 2 O 4 sensor exhibited remarkable acetone-sensing performance with a high response of 13.77 at 1 ppm, a detection limit as low as 20 ppb (theoretically as low as 171 ppt), strong humidity adaptability, a fast response time of 17 s at 1 ppm, exceptional selectivity, and long-term stability. In practical applications, the Ni 0.6 Zn 0.4 Fe 2 O 4 sensor was able to distinguished between acetone levels in the breath of healthy individuals and simulated diabetes patients, thereby suggesting their potential for auxiliary diabetes diagnosis. The results imply that normal/inverse spinel ferrite heterojunction composites could offer a novel strategy for effective acetone detection in breath analysis for the diagnosis of diabetes.