Microwave-assisted synthesis of nitrogen, phosphorus-doped Ti3C2 MXene quantum dots for colorimetric/fluorometric dual-modal nitrite assay with a portable smartphone platform

Ti(3)C(2 & nbsp;)MXene quantum dots (Ti(3)C(2 & nbsp;)MQDs) are recognized as promising new nanomaterial recently, while the majority of the Ti(3)C(2 & nbsp;)MQDs manifest limited maximum emission in the blue-light range. Herein, the green fluorescence nitrogen, phosphorus-doped Ti(3)C(2 & nbsp;)MQDs (N, P-Ti(3)C(2 & nbsp;)MQDs) were synthesized via facile microwave assisted method, which greatly reduces the reaction time. The as-prepared N, P-Ti(3)C(2 & nbsp;)MQDs showed excitation dependent photoluminescence, anti-photobleaching, and favorable dispersibility. Interestingly, the fluorescence of N, P-Ti(3)C(2 & nbsp;)MQDs can be quenched by 1,10-phenanthroline-Fe (II) complex (Phen-Fe2+) via inner filter effect (IFE), accompanied by the increased orange color. After introduction of nitrite (NO2-), owing to the redox reaction between NO2- and Fe2+, the fluorescence will be recovered and the color varies from orange to colorless gradually. Therefore, a colorimetric/fluorometric dual-modal recognition of NO2- was fabricated based on N, Ti3C2 & nbsp; MQDs and Phen-Fe2+ complex. Moreover, paper-based test trips were facilely made by the N, P-Ti(3)C(2 & nbsp;)MQDs/Phen-Fe2+& nbsp; sensing system in response to ultrafast-response, real-time detection of NO2- with the assistant of smartphone. This study tendered a novel dual-channel method for real-time visual assay of NO2- as well as provided insightful research into functionalized Ti(3)C(2 & nbsp;)MQDs regarding in food analysis.

Automated summary

Ti(3)C(2)MXene quantum dots (Ti(3)C(2)MQDs) have been synthesized and demonstrated green fluorescence, which can be used for colorimetric and fluorometric dual-modal recognition of nitrite (NO2-). Paper-based test strips were also made for real-time detection of NO2-.