Loading uniform Ag₃PO₄ nanoparticles on three-dimensional peony-like WO₃ for good stability and excellent selectivity towards NH₃ at room temperature

A heterojunction structure design is a very good method for improving the properties of semiconductors in many research fields. This method is employed in the present study to promote the gas-sensing performance of Ag3PO4 nanocomposites at room temperature (25 & DEG;C). A nanocomposite of Ag3PO4 nanoparticles and three-dimensional peony-like WO3 (WO3/Ag3PO4) was successfully prepared by the precipitation method. The crystalline phases were analyzed by x-ray diffraction and the microstructure was characterized by scanning electron microscopy and transmission electron microscopy. The chemical bonding states were analyzed by x-ray photoelectron spectroscopy. The gas-sensing performance of WO3/Ag3PO4 sensors was systematically explored at room temperature. The composite sensors possessed a higher response and lower detection limit (1 ppm) to NH3 than those made of a single type of material; this is ascribed to the synergistic effect achieved by the heterojunction structure. Among the different composite sensors tested, gas sensor A5W5 (Ag3PO4:WO3 mass ratio of 5:5) displayed the highest response to NH3 at room temperature. Interestingly, the A5W5 gas sensor exhibited relatively good stability and excellent selectivity to NH3. The A5W5 sensor also displayed a relatively good response under high humidity. The gas-sensing mechanism of the WO3/Ag3PO4 sensors is explained in detail. Taken together, the as-prepared sensor is highly efficient at detecting NH3 and could be suitable for practical applications. In addition, this study also provides a new method for developing Ag3PO4-based sensors in the gas-sensing field.