Nanoheterostructure Construction and DFT Study of Ni-Doped In₂O₃ Nanocubes/WS₂ Hexagon Nanosheets for Formaldehyde Sensing at Room Temperature

A high-performance formaldehyde sensor based on nickel (Ni)-doped indium trioxide (In₂O₃)/tungsten disulfide (WS₂) nanocomposite was demonstrated. An epoxy substrate served as matrix of the Ni-In₂O₃/WS₂ nanocomposite sensor. The material properties of self-assembled Ni-In₂O₃/WS₂ nanoheterostructure were fully characterized and confirmed. The formaldehyde-sensing properties of the Ni-In₂O₃/WS₂ composite were tested at 25 °C. Compared to the In₂O₃, WS₂, and their composite, the Ni-In₂O₃/WS₂ sensor demonstrated significant improvement on the formaldehyde-sensing performance, including a low detection limit of 15 ppb, good selectivity, repeatability, fast detection rate, and a fair logarithmic function toward formaldehyde concentration. The dramatically enhanced sensing performance of Ni-In₂O₃/WS₂ film sensor can be attributed to the Ni ion doping and synergistic interfacial incorporation of In₂O₃/WS₂ heterojunction. The sensitive mechanism of the Ni-In₂O₃/WS₂ film sensor toward formaldehyde is explored through density functional theory (DFT) simulation. This work verified that the synthesis of Ni-doped In₂O₃/WS₂ nanofilm provides a new avenue to develop promising hybrids for formaldehyde sensing.