Synthesis of high-efficient red carbon dots for pH detection

Abstract

A facile one-step solvothermal route for the preparation of high-efficient red fluorescence carbon dots (RCDs) is developed using 2-aminophenol as carbon source. The as-prepared RCDs indicate excitation-independent emission at 615 nm, high absolute photoluminescence (PL) quantum yield (24%) in ethanol, excellent water solubility, high optical stability and sensitive pH response behavior. The RCDs-based “off-on” reversible probe can be used to detect H+ and OH−. The quenching and recovering effects can be obviously observed by naked eyes due to the combination effect between the target ions and the surface functional groups of RCDs, resulting in breaking or recombination of the quenchers. Moreover, a remarkable fluorescence enhancement behavior with the increase of pH from 4 to 13 can be induced by the RCDs, which can be also used to detect H+ and OH− in urine of cattle and lake water, exhibiting a promising platform of the RCDs for environmental and biological sensing applications.