RESUMO
Dual-fluorescence carbon dots have great potential as nanosensors in life and materials sciences. Such carbon dots can be obtained via a solvothermal synthesis route with glutathione and formamide. In this work, we show that the dual-fluorescence emission of the synthesis products does not originate from a single carbon dot emitter, but rather from a mixture of physically separate compounds. We characterized the synthesis products with UV-vis, Raman, infrared, and fluorescence spectroscopy, and identified blue-emissive carbon dots and red-emissive porphyrin. We demonstrate an easy way to separate the two compounds without the need for time-consuming dialysis. Understanding the nature of the system, we can now steer the synthesis toward the desired product, which paves the way for a cheap and environmentally friendly synthesis route toward carbon dots, water-soluble porphyrin, and mixed systems.
RESUMO
Operando shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) with on-line mass spectrometry (MS) has been used to investigate the surface species, such as NO, NOH, NO2 , N2 O, and reaction products of the NO reduction reaction with CO and H2 over supported Rh-based catalysts in the form of catalyst extrudates. By correlating surface intermediates and reaction products, new insights in the reaction mechanism could be obtained. Upon applying different reaction conditions (i. e., H2 or CO), the selectivity of the catalytic reaction could be tuned towards the formation of N2 . Furthermore, in the absence of Rh, no reaction products were detected. The importance of the operando SHINERS as a surface-sensitive characterization technique in the field of heterogeneous catalysis provides routes towards a better understanding of catalytic performance.
