UV-activated high-performance formaldehyde gas sensor based on P25/ZnO microspheres

Implementing sensitive and fast formaldehyde (HCHO) sensing at room temperature is still in extreme demand for practical indoor air quality monitoring. Herein, we synthesized P25/ZnO sensing materials for detecting low-concentration HCHO at room temperature. The sensing mechanism based on the P25/ZnO heterojunction was analyzed by the surface photovoltage (SPV), transient photovoltage (TPV), and X-ray photoelectron spectroscopy (XPS) results. Based on the P25/ZnO heterojunction, the obtained 1% P25/ZnO has the highest response among the synthesized sensing materials. The response of 1% P25/ZnO sensor materials to 0.9ppm and 19.1ppm HCHO reaches 44.85% and 255.42%, respectively, which is 21 and 20 times that of ZnO sensor materials (0.9ppm similar to 2.16%, 19.1ppm similar to 12.64%). Furthermore, the detection limit can be as low as 82 ppb under 360 nm light at room temperature. The selectivity, long-term stability, and repeatability of the obtained sensors at room temperature were also revealed.