Synergy Engineering of d‐Band Center and Multi‐Phase Interface Charge Transport in Ternary Co ₃ O ₄ /Pt/ Bi ₂ MoO ₆ Hierarchical Heterojunction Arrays for Superior VOCs Sensing

Resistive semiconductor gas sensor provides a low‐cost method for the detection of volatile organic compounds in the environment. However, the slow adsorption kinetics of volatile organic compound molecules during the gas–solid recognition interface, along with the high resistance to charge transfer in the carrier conversion interface, represent two significant challenges in semiconductor sensing reactions. Here, a ternary Co 3 O 4 /Pt/Bi 2 MoO 6 hierarchical heterojunction array is designed, which consists of Co 3 O 4 nanowire as the internal skeleton, Pt nanoparticles as the intermediate charge transfer layer, and Bi 2 MoO 6 nanorods as the outer molecular sieving layer. It exhibits an impressive sensing activity towards volatile organic compound triethylamine. Its response value to 100 ppm triethylamine can reach 34.07 (300 °C), which is approximately 1.34, 2.45, and 8.34 times greater than that observed for binary Co 3 O 4 /Bi 2 MoO 6 heterojunction, Co 3 O 4 /Pt heterojunction, and pristine Co 3 O 4 , respectively. Furthermore, the ternary heterojunction demonstrates a low detection limit of 418 ppb alongside rapid response/recovery, excellent selectivity, acceptable humidity tolerance, and long‐term stability over 4 months. It is revealed that the design of the ternary hierarchical heterojunction not only optimizes the d‐band center and thus gas adsorption activity on gas–solid recognition interfaces, but also achieves efficient multi‐phase interface charge transfer during carrier conversion. Moreover, the in‐situ growth of the array effectively addresses a range of issues associated with traditional thick‐film devices. This study not only achieves synergistic optimization of volatile organic compound adsorption reaction and interface charge transfer through the in‐situ construction of ternary hierarchical heterojunction arrays, but also provides novel insights into designing semiconductor sensing materials at the electronic level based on d‐band center regulation.