TiCT MXene Quantum Dots (MQDs) were obtained with high yield (60%) from two-dimensional MXene via a facile reflux strategy. These green luminescent MQDs possess indisputable and stable annihilation electrochemiluminescence (ECL) and coreactant (TPrA) enhanced (∼29-fold) anode ECL.
Although
electrochemiluminescence (ECL) has been developed significantly
in the past few decades, ECL efficiency in aqueous solutions remains
quite low. Determination of the energy losses and development of new
ECL-enhancing strategies are still of great value. In this work, we
discovered a detrimental nonradiation relaxation pathway by a concurrent
oxygen evolution reaction (OER) process in a well-known ruthenium(II)
tris(2,2′-bipyridyl) (Ru(bpy)3
2+) aqueous
ECL system due to similar surface-sensitive characteristics, and for
the first time, a chemical strategy was developed by which carbon
nitride quantum dots (CNQDs) could inhibit the surface OER process,
alleviate the energy losses by nonradiation relaxation, and enhance
the anodic ECL of Ru(bpy)3
2+. In the Ru(bpy)3
2+/CNQD system, CNQDs could enhance the anodic
ECL of Ru(bpy)3
2+ in a nitrogen stream (10-fold)
and ambient air (161-fold). The luminous and nitrogen-rich CNQDs were
also confirmed not to serve as ECL luminophores, anodic coreactants,
or donor/acceptors in ECL. The coreactant-free Ru(bpy)3
2+/CNQD system possesses several advantages over the common
coreactant ECL system, such as low dosage (100 μg/mL CNQDs),
favorable regeneration capacity, etc. As an example, ECL on–off
detection of dopamine utilizing the Ru(bpy)3
2+/CNQD system was also developed to show prospects in ECL sensing.
Besides, CNQDs were introduced into the classical Ru(bpy)3
2+/C2O4
2– coreactant
ECL system, leading to suppressed OER and improved ECL signal. Overall,
the proposed new ECL-enhancing strategy is promising for applicable
ECL sensing, could be extended to other ECL luminophores with high
oxidation potential, and enables an in-depth understanding of the
ECL process and mechanism.
In this study, electrochemiluminescence (ECL) properties of carbon dots (CDs, less than 10 nm) have been investigated. Such CDs were fabricated via electrochemical etching strategy from graphite rods. Subsequently, a series of CDs were prepared through controlled surface engineering technique by a wet chemical method, including the oxidized-CDs (oCDs), partially reduced-CDs (rCDs), and fully reduced-CDs (F-rCDs). In-depth characterizations including UV−vis, FT-IR, Raman, XPS, etc. revealed significant differences in features of these CDs, especially the condition of surface grafted oxygen containing functional groups. ECL results suggested that all of the annihilation ECL of CDs, oCDs, and rCDs demonstrated a stable positively charged luminophore (R +• ) and an unstable negatively charged luminophore (R −• ) at the surface of GCE and possessed a 365 nm emission peak and consistent emission range from 550 to 850 nm. During further structural mode investigation and ECL properties simulation, the surface construction nature of CDs was speculated and the significant role of oxygen containing groups in ECL behavior of CDs was also verified. According to the ECL behavior from all of these samples, the probable ECL mechanism of CDs was then proposed, which further interpreted the indispensable contributions of oxygen containing functional groups to the ECL property of CDs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.