N-Doped Carbon Quantum Dots for Differential Detection of Doxycycline in Pharmaceutical Sewage and in Bacterial Cell

For the past two years, doxycycline has been employed hugely for the treatment of COVID 19 over the globe. Excessive use of doxycycline can result in bacteria and gene resistance, which affects the future treatment of infectious diseases. Furthermore, unused doxycycline left from the hospital and pharmaceutical industries may have an adverse effect on the environment, posing a significant menace to modern society. As a result, doxycycline detection is required. Herein, we developed blue luminous nitrogen-doped carbon quantum dots (N-CQDs) using ascorbic acid and diethylenetriamine (DETA) as carbon and nitrogen sources via a microwave-assisted technique for the differential detection of doxycycline (DC) via a fluorescence quenching mechanism, even when other tetracycline derivatives interfere. The quenching mechanism has been elaborately explained by using a Stern-Volmer plot, UV-vis and fluorescence spectroscopy, and TCSPC to attribute the static quenching and inner filter effect. In addition, the limit of detection of our suggested sensor is 0.25 μM. To confirm the structural properties and the size of the N-CQDs, FT-IR, Raman spectroscopy, HRTEM, DLS, and EDX have been performed. Moreover, this approach was used to identify doxycycline in pharmaceutical waste and bacterial cells. Because of its great sensitivity and selectivity, N-CQDs are ideal for measuring DC in environmental applications. © 2022 American Chemical Society. All rights reserved.

Hydrophobic RuO2/Graphene/N-doped porous carbon hybrid catalyst for Li-air batteries operating in ambient air

Li–air batteries have received significant attention for their ultrahigh theoretical energy density. However, the byproducts induced by attacking air hinder the conversion of Li–O2 batteries to Li–air batteries. Humidity is one of the main obstacles, not only causing side reactions with the discharge products but also leading to rapid corrosion of the lithium anode. Here, we fabricated a novel composite hydrophobic catalyst by loading RuO2 and graphene on N-doped porous carbon. The catalyst was endowed with hydrophobicity and showed superior catalytic performance and low affinity to water in the air. A Li–air battery equipped with this novel composite catalyst exhibited eminent cycling performance in pure oxygen (over 470 h), humid oxygen [∼40% relative humidity (RH), over 310 h], and ambient air (∼42% RH, over 330 h) at a current density of 500 mA g−1, and the discharge specific capacity increased from 13122.1 to 19358.6 mAh g−1. © 2022