In situ decoration of AuPd nanoparticles on MOF derived ZnO for ultra-high response and low detection limit trimethylamine detection.

BACKGROUND

Trimethylamine (TMA) is a colorless, volatile gas with a strong irritating odor. Prolonged exposure to a certain amount of TMA can cause symptoms such as dizziness, nausea and difficulty breathing, and may even be life-threatening. Therefore, effective detection of TMA is crucial. Gas sensors, due to their convenience, affordability and ability to real-time detect volatile gases including TMA, are increasingly favored. However, gas sensors based on single metal oxide materials have numerous drawbacks and may not meet practical requirements. Therefore, it is necessary to modify gas-sensitive materials to achieve sensors with higher sensitivity and selectivity at lower operating temperatures.

RESULTS

In this research, gas-sensitive materials for detecting TMA were synthesized using liquid-phase methods. Firstly, metal-organic framework-derived ZnO nanoparticles were prepared via a co-precipitation method, followed by the in-situ reduction method to prepare ZnO modified with Au, Pd, and AuPd bimetallic nanoparticles. The experimental results revealed that when the total loading of AuPd was 2 wt% and the ratio was Au:Pd = 1:1, the gas-sensitive performance was enhanced significantly. The AuPd-ZnO sensor exhibited a remarkable high response of 1608.3 to 100 ppm TMA at 200 °C, which was approximately 140 times that of pristine ZnO (R/R = 11.5, 275 °C), and the optimal operating temperature was reduced by 75 °C. Additionally, the sensor boasted a rapid response time (3 s), and low detection limit (50 ppb), high selectivity along with good long-term stability.

SIGNIFICANCE

The modified material can enable lower power consumption, increased sensitivity and enhanced stability for real-time detection of TMA. Combined with multiple characterization methods, the sensing mechanism of performance improvement was analyzed, which benefited from the electronic and chemical sensitization of Au and Pd, along with the synergistic effect of the AuPd bimetal. This research provided an effective strategy for the design of high-performance TMA gas sensors.