Tunable multi‐color S/N co‐doped carbon quantum dots synthesized from wasted foam and application to detection of Cr 3+ ions

IN THIS PAPER, THROUGH ADJUSTING SULFURIC ACID CONCENTRATION, TUNABLE MULTI-COLOR S/N-CQDS WERE SYNTHESIZED WITH WASTED FOAM AS RAW MATERIAL. THE S/N-CQDS PRESENTED BLUE, BLUE-GREEN, GREEN, GREEN-YELLOW AND YELLOW-EMITTING IN THE CASE OF EMISSION PEAK SHIFTING FROM 475 NM TO 589 NM WITH THE OPTIMAL EXCITATION WAVELENGTHS OF 385 NM, 405 NM, 440 NM, 450 NM, AND 500 NM, RESPECTIVELY. THE MORPHOLOGY OF S/N-CQDS WERE SPHERICAL WITH SIZE AROUND 6-8 NM BY TEM. THE FT-IR SPECTRA AND XPS INDICATED THAT THE SURFACE OF S/N-CQDS WAS HIGHLY OXIDIZED AND SULFUR DOPED. THE FLUORESCENT MECHANISM OF MULTI-COLOR S/N-CQDS EMISSION WAS MAINLY RELATED TO THE BAND GAP CHANGE CAUSED BY THE SURFACE STATE. FURTHERMORE, BLUE-EMITTING S/N-CQDS WERE EMPLOYED AS A FLUORESCENT PROBE, WHICH HAD HIGH SELECTIVITY AND SENSITIVITY TO CR3+ IONS WITH A LOW DETECTION LIMIT OF 6 ΜM. THE WASTED FOAM DERIVED S/N-CQDS EXHIBITED PROMISING POTENTIAL FOR IONS DETECTION IN ACTUAL WATER SAMPLES DUE TO ITS EXCELLENT FLUORESCENCE ACTIVITY.