Simultaneous fluorescence sensing of vitamin B2 and sulfur ions based on fluorescent copper nanoparticles.

In this study, the F-CuNPs were synthesized by a modified liquid-phase chemical reduction method. Throughout the preparation process, anhydrous copper sulfate was used as the copper source, and ascorbic acid in the NaOH solution served as the reducing and protective agent. Förster resonance energy transfer (FRET) may exist between F-CuNPs and vitamin B2 due to the large spectral overlap between the fluorescence emission spectra of F-CuNPs and the UV-vis absorption spectra of vitamin B2. Therefore, the detection of vitamin B2 was designed based on a FRET system between F-CuNPs and vitamin B2. With S2- into the F-CuNPs&VB2 system, the fluorescence intensity of vitamin B2 was quenched, while the fluorescence intensity of F-CuNPs was almost unchanged. There may be a specific reaction between S2- and vitamin B2. Therefore, the research system can be further used to detect S2- based on ratiometric fluorescent probe. The research findings show that the linear range of vitamin B2 was 0.51 nM-34.64 nM with a detection limit of 0.25 nM (S/N = 3), the linear range of S2- was 0.64 µM-60.00 µM with a detection limit of 0.32 µM (S/N = 3). Furthermore, the simultaneous fluorescent sensing system has high sensitivity and selectivity. Therefore, this system was designed and successfully used to detect the content of vitamin B2 and S2- in actual samples to find a new effective method to detect analytes.

Electrochemical nitrogen reduction to ammonia at ambient conditions on nitrogen and phosphorus co-doped porous carbon.

Reduction of nitrogen (N2) under ambient conditions and understanding the mechanism have been hugely challenging problems for decades. Herein, we for the first time report that N,P co-doped hierarchical porous carbon (NPC) can serve as an electrocatalyst for the nitrogen reduction reaction (NRR) in an acid aqueous solution under ambient conditions. The faradaic efficiency (FE) and yield of production of NH3 on the NPC electrode reached as high as 4.2% and 0.97 µg h-1 mg-1cat., respectively. Furthermore, the electrocatalytic NRR mechanism on the NPC electrode was undoubtedly confirmed by electrochemical in situ Fourier transform infrared spectroscopy, and follows an associative pathway. These results are predicted to offer a new platform in the rational design and synthesis of highly efficient electrocatalysts for the NRR under ambient conditions.