Water‐Soluble Fluorescent Carbon Quantum Dots and Photocatalyst Design

Abstract

Carbon nanostructures are attracting intense interest because of their many unique and novel properties. The strong and tunable luminescence of carbon materials further enhances their versatile properties; in particular, the quantum effect in carbon is extremely important both fundamentally and technologically. [1][2][3][4] Recently, photoluminescent carbonbased nanoparticles have received much attention. They are usually prepared by laser ablation of graphite, electrochemical oxidation of graphite, electrochemical soaking of carbon nanotubes, thermal oxidation of suitable molecular precursors, vapor deposition of soot, proton-beam irradiation of nanodiamonds, microwave synthesis, and bottom-up methods.[5-13] Although small (ca. 2 nm) graphite nanoparticles show strong blue photoluminescence (PL), [13] definitive experimental evidence for luminescence of carbon structure arising from quantum-confinement effects and size-dependent optical properties of carbon quantum dots (CQDs) remains scarce.Herein, we report the facile one-step alkali-assisted electrochemical fabrication of CQDs with sizes of 1.2-3.8 nm which possess size-dependent photoluminescence (PL) and excellent upconversion luminescence properties. Significantly, we demonstrate the design of photocatalysts (TiO 2 /CQDs and SiO 2 /CQDs complex system) to harness the use of the full spectrum of sunlight (based on the upconversion luminescence properties of CQDs).

Successful entrapment of carbon dots within flexible free-standing transparent mesoporous organic-inorganic silica hybrid films for photonic applications

“…These properties have led to a series of potential applications as in light emitting diodes [2,3], solar cells [4,5], sensing [6], catalysis [7], integration in photovoltaic devices etc. [8] and more importantly to a possible breakthrough in biosensing, bioimaging [9][10][11][12][13] and medical diagnosis [14].…”

Enhanced photoluminescence and characterization of multicolor carbon dots using plant soot as a carbon source

“…However, the large scale preparation and surface passivation of C-dots are still expected to provide highly fluorescent C-dots by using economical and facile approaches. Up to now, various carbon sources have been used to prepare C-dots such as laser ablation of graphite [19,20], electrochemical treatment of graphite [21], commercial activated carbon by bottom-up method [9], heating carbohydrate, watermelon peels or PEG with microwave pyrolysis [22][23][24]. The prepared C-dots are highly water-soluble, nano-sized and multi-colourful.…”

Synthesis of TiO₂/Carbon Nanoparticle (C-dot) Composites as Active Catalysts for Photodegradation of Persistent Organic Pollutant

“…Here, we are reporting a new material with improved TiO 2 photocatalytic activity under UV light, by using a light absorber material, carbon nanoparticles (C-dots), to form TiO 2 composites. The synthesized composite is a natural progression from the results reported by Li et al [8] who mixed carbon quantum dots (CQDs) with TiO 2 and used it to photodegrade methylene blue with efficiency close to 100%.…”

“…TiO 2 can degrade organic pollutants into environmentally safe products, such H 2 O and CO 2 [7]. However, TiO 2 is an active photocatalyst in the UV light region due to its large intrinsic band gap [8], limiting its usage in large scale, as UV light sources are relatively small. Sunlight, an abundant light source, is composed of less than 5% of UV light, with the largest composition in visible light.…”

“…C-dots have strong luminescence property in the UV-tonear-infrared range [8]. In this study, C-dots were combined with TiO 2 and used as a catalyst in the photodegradation of PCE.…”