Raspberry-like mesoporous Co-doped TiO2 nanospheres for a high-performance formaldehyde gas sensor

Abstract

The effective detection of formaldehyde is of great importance to people's daily life. Titanium oxide (TiO₂) based nanomaterials have great promise for formaldehyde detection due to their wide availability, easy utilization and abundant surface reactions. However, currently their actual application is still limited by their relatively low sensitivity, high working temperature and poor selectivity. To address these issues, herein we develop a template-assisted self-assembly strategy to realize the simultaneous chemical doping and morphological control of TiO₂ nanostructures. The resultant Co-doped TiO₂ nanospheres show a cobalt content of up to 2.95 wt% and a unique raspberry-like mesoporous morphology composed of numerous superfine nanopores of 4.9–7.8 nm, which provides a large specific surface area (∼175 m² g⁻¹) and high porosity (0.438 cm³ g⁻¹) to the product. The gas sensor device shows a sensitivity of ∼84.8 for 10 ppm formaldehyde, which exceeds that of most of the similar metal oxides reported recently and likely stands for the state-of-the-art merit of formaldehyde sensors. Meanwhile, the sensor also shows significantly decreased working temperature (∼86 °C) and unique selectivity. All this makes our chemically doped raspberry-like mesoporous TiO₂ product a very promising candidate for future formaldehyde sensors.