Ag-doped boron quantum dots with enhanced stability and fluorescence enabling versatile practicality in visual detection, sensing, imaging and photocatalytic degradation.

In this work, a metal-doping strategy was put forward to construct metal-doped borophene and the corresponding zero-dimensional boron. Through theoretical calculations, Ag acts as the optimal metal ions to prepare Ag-doped borophene derived boron quantum dots (Ag-BQDs). As predicted theoretically, doping of Ag endows borophene with enhanced stability of electronic structures. The newly emerging Ag-BQDs were experimentally acquired from ultrasonic-assisted liquid-phase exfoliation of bulk boron and solvothermal treatments. According to theoretical and experimental studies, the improved stability and fluorescence (FL) of Ag-BQDs are due to the formation of strong B-Ag bonding to competitively suppress B-O bonding. The function enables the maximal protection of borophene electronic structures from oxidization, destruction and reconfiguration. Because of Ag-BQDs with relatively higher colloidal and FL stability over BQDs, potential applications of Ag-BQDs were further explored in promising fields toward FL visualization in aqueous solutions and on filter paper, employed as a chemosensor of Fe for FL sensing and visual detection at the solid/liquid phases, utilized for multiple FL bio-imaging at the levels of fresh plants, live animals and live cells of fresh plants, and applied to photocatalytic degradation of organic dyes and anticancer drug. Experimental results demonstrate excellent performances of Ag-BQDs in multiple applications, including versatile FL sensing and visual detection, unique multi-channel FL bio-imaging and visible-light-driven photodegradation of organic pollutants, toxic and harmful substances. This work can promote the development of metal-ion-doped low- dimensional nanomaterials with improved stability and FL properties for significant applications.