Layered Double Oxides for Sensing Reducing Volatile Organic Compounds: The Effect of Local Charge Region Modulation

Multi-metal oxides with uniform distribution of various metal elements have potential for an enhanced gas-sensing response due to the strong heterogeneous and synergistic effects involved. In this study, three layered double oxides, labeled as CuCr-, ZnCr-, and ZnTi-LDOs, respectively, were prepared with corresponding LDHs (layered double hydroxides) as precursors and self-sacrificial templates. The elemental mapping confirms the uniform distribution of hetero-metal elements in whole LDOs. The CuCr-LDOs exhibits a much larger sensing response towards reducing VOCs at room temperature, which is 3.5 or 13.3 times that of ZnCr- or ZnTi-LDOs, respectively. The response differences are analyzed in terms of the local charge region modulation associated with heterojunction formation, and it is further demonstrated based on first-principles calculations and valence electron theory. The present work suggests a possible strategy for developing highly sensitive oxide-based gas sensors for VOCs detection.