Facile fabrication of p-n heterostructure based on Pt/NiO-CeO2 nanosheet-assembled hierarchical structures for selective detection of benzene vapour

We report on the fabrication of NiOCeO₂ nanosheet-assembled hierarchical structures loaded with various weight percentages of Pt for selective detection of low concentrations of benzene vapour at low functional temperatures. Surface analyses showed that the nanomaterials are made of nanosheet-assembled hierarchical structures. Meanwhile, the structural X-ray photoelectron spectroscopy analyses confirmed the loading of Pt on the surface of NiOCeO₂ heterostructures. The sensing findings showed that the 1.0 wt.% Pt-loaded NiOCeO₂ sensor showed more sensitivity to benzene, amongst other target analytes. The sensor demonstrated a superior response of 2.7 to 2 ppm benzene, a sensitivity of 0.87 ppm^-1, and a minimal detection limit of 0.07 ppm at a functional temperature of 100 °C. The sensor was very stable to benzene in the presence of 40–70 % relative humidity. Increasing the temperature, both the response and sensitivity reduced, while the detection limit increased, showing that 100 °C is an optimal temperature. The improved sensing characteristics were associated with higher surface defects and surface area, as well as the loading of Pt, which acted as a catalyst for benzene adsorption. The smaller optical band gap offered extra adsorption sites for benzene to capture electrons in the conduction band easily. The strong catalytic effect of Pt significantly enriched the sensitivity of chemical and electronic sensitization. The sensing mechanism linked to the benzene detection induced by the loading of Pt was discussed in detail.