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 MXene quantum dots (Ti 3 C 2 MQDs) are recognized as promising new nanomaterial recently, while the majority of the Ti 3 C 2 MQDs manifest limited maximum emission in the blue-light range. Herein, the green fluorescence nitrogen, phosphorus-doped Ti 3 C 2 MQDs (N, P-Ti 3 C 2 MQDs) were synthesized via facile microwave-assisted method, which greatly reduces the reaction time. The as-prepared N, P-Ti 3 C 2 MQDs showed excitation-dependent photoluminescence , anti-photobleaching, and favorable dispersibility . Interestingly, the fluorescence of N, P-Ti 3 C 2 MQDs can be quenched by 1,10-phenanthroline-Fe (II) complex (Phen-Fe 2+ ) via inner filter effect (IFE), accompanied by the increased orange color. After introduction of nitrite (NO 2 - ), owing to the redox reaction between NO 2 - and Fe 2+ , the fluorescence will be recovered and the color varies from orange to colorless gradually. Therefore, a colorimetric/fluorometric dual-modal recognition of NO 2 - was fabricated based on N, P-Ti 3 C 2 MQDs and Phen-Fe 2+ complex. Moreover, paper-based test trips were facilely made by the N, P-Ti 3 C 2 MQDs/Phen-Fe 2+ sensing system in response to ultrafast-response, real-time detection of NO 2 - with the assistant of smartphone. This study tendered a novel dual-channel method for real-time visual assay of NO 2 - as well as provided insightful research into functionalized Ti 3 C 2 MQDs regarding in food analysis.