Preparation And Application Of Red-emissive Carbon Dots

Recently,carbon dots（CDs）have received remarkable attention in optoelectronic devices,bioimaging,catalysis,sensing and anti-counterfeiting,due to the fascinating merits of good photostability,low cytotoxicity,and excellent biocompatibility.Red-emitting CDs（RCDs）could significantly boost the contrast,eliminate background interference,and therefore widen its potential application.Fluorescence detection is a common analytical assay due to its low cost,convenience and high sensitivity and specificity.The interaction between CDs and analytes causes changes in the fluorescence properties of CDs resulting in multiple signals for selective and sensitive monitoring of the analytes.In this work,red emissive carbon dots（RCDs）were prepared using a simple hydrothermal method in ethanol from o-phenylenediamine as the precursor.Firstly,the effect of different structured protonic acids on the preparation of red carbon dots from o PD was investigated,and it was found that protonic acids containing electron-absorbing groups promoted the efficiency of converting red carbon dots during the synthesis of o PD.The red carbon dots（RCDs-C）prepared from o-phenylenediamine and catechol were then selected as the target products to investigate their specific physicochemical properties.It was found that the prepared RCDs-C had trigonal fluorescence emission at 597,647 and 706 nm,respectively,and contained functionalised amino,hydroxyl and carboxyl groups on their surfaces,which provided a theoretical basis for the subsequent investigation of the application of red carbon dots.Secondly,in terms of fluorescent probe detection,a new carbon dot-based fluorescent chemical sensor for permanganate was developed using the internal filtration effect method.The sensor was successfully used for quantitative detection of Mn O₄^-for practical water samples analysis with satisfactory recovery results.The emission peaks of the RCDs-C at 597 and 647nm were quenched with increasing copper ion concentration and the detection line was 0.25μM in the range of 0-7μM.The quenching mechanism was the ACQ effect,due to accelerated aggregation of RCDs-C by the formation of hydrogen bonds between oxygen-containing functional groups on the surface of the RCDs and Cu²⁺.Finally,our group experimented with the application of carbon dots in smart textiles.Due to the color of the RCDs-C solution show obvious changes in different p H,their solid powder was used as an advanced luminescent carbon material for smart textile applications,developing a textile pattern for monitoring volatile acids in the surrounding environment.Furthermore,the as-prepared RCDs-C was exploited as solid-state red fluorescent pigments for smart textile applications,the bright red fluorescence patterns can be clearly seen when excited in a dark environment.The present RCDs-C material would therefore contribute to the development of smart textiles and optical probes.