Hierarchical engineering of BiVO4 via In doping and PdO loading for high-performance acetone sensing

A hierarchical modification strategy involving In doping and subsequent PdO loading was developed to significantly enhance the acetone sensing properties of BiVO 4 . The pristine BiVO 4 (BVO), In-doped BiVO 4 (In-BVO), and PdO-loaded In-BiVO 4 (Pd/In-BVO) were systematically synthesized and evaluated. The gas sensing results demonstrated that the response to 100 ppm acetone was substantially improved from 10 (BVO) to 15 (In-BVO) and further to 22 (Pd/In-BVO). Notably, the operating temperatures of BVO and In-BVO were both 310 °C, while that of Pd/In-BVO was meaningfully reduced to 270 °C. Furthermore, the theoretical limit of detection was lowered to 50 ppb for the Pd/In-BVO, compared to 199 ppb for pure BVO. Combined characterizations revealed that In doping introduced acidic sites to enhance acetone adsorption, while simultaneously lowering the oxygen desorption temperature. The subsequent PdO loading not only amplified these effects but also introduced a PdO/BiVO 4 heterojunction along with metallic Pd, which collectively promoted carrier separation, increased charge carrier concentration, and facilitated the adsorption and activation of oxygen species. This work provides a profound insight into the design of high-performance gas sensors through multi-step engineering.