Upconversion carbon quantum dots as visible light responsive component for efficient enhancement of photocatalytic performance

Carbon Quantum Dots: A Component of Efficient Visible Light Photocatalysts

“…A large number of recent work concerning about the photocatalytic applications of CQDs have suggested the contribution of their UCPL properties. Ke et al [49] used TiO 2 photocatalysts modified with CQDs to obtain a 3.6 times higher rate of MB degradation under visible light irradiation (λ > 420 nm) when compared with pure TiO 2 , and the enhanced photocatalysis was mainly ascribed to the increased amount of oxidative radicals in hypothesis of the up-conversion process from CQDs ( Figure 7A). Similar results have also been observed with CQDs/g-C 3 N 4 hybrids, as shown by Zhang et al [50].…”

Introducing carbon dots to moderate the blue emission from zinc vanadium oxide hydroxide hydrate nanoplates

“…The absorption curve (black line) shows an intense peak at $284 nm that can be assigned to C]C bond localized p* ) p excitations and a much weaker tail stretching to longer wavelengths consistent with a C]O bond localized p* ) n transition. 31,32 The PL spectra taken at progressively longer excitation wavelengths (l ex ), stepping in 20 nm increments between 320 and 500 nm (colored line), reveal a clear l exdependence to the peak emission wavelength (l em ) and its intensity, though we recognize that the latter dependence must be convoluted with the l ex -dependent excitation light intensity. As noted elsewhere, such observations point to the existence of a range of emission traps at surface sites on the CQDs.…”

CQD-Based Composites as Visible-Light Active Photocatalysts for Purification of Water

“…Additionally, it displays strong blue photoluminescence and good optical absorption in the UV and near-visible region [60]. Futhermore, CQDs exhibit upconversion photoluminescence properties [19,[61][62][63] and exhibit promising electron transfer properties [64,65]. These optical characteristics of CQDs render them promising candidates as photosensitizers for photocatalytic applications.…”

“…Firstly, CQD can be excited by a low-energy radiation to generate holes (h þ vb ) and electrons (e À cb ). Under favorable thermodynamic condition, the photogenerated e À cb is injected into the conduction band of a wide bandgap photocatalyst (such as TiO 2 ) to initiate a reaction as shown in Figure 5(a) [19]. Secondly, the CQDs with upconversion PL properties can convert longer wavelength light to the short wavelength light, which in turn can excite a wide bandgap photocatalyst (ZnO) to form e Recently, several reports have been published that show CQDs to dramatically extend the optical absorption range of wide and narrow bandgap photocatalysts to the entire visiblelight range and beyond [18-21, 58, 60, 62, 68-71].…”

“…This relatively new material has attracted huge interest in many fields including, but not limited to, electrocatalysis [6], biosensing [7][8][9][10], bioimaging [11][12][13][14], chemical sensing [15], and nanomedicine [16], due to their unique tunable photoluminescence (PL) properties, chemical inertness, high water solubility, ease and low cost of fabrication and, more importantly, low toxicity. Additionally, CQDs have also attracted considerable interest in various photocatalytic applications-environmental remediation [17][18][19][20][21], water splitting to produce H 2 production [22][23][24][25][26][27], CO 2 conversion [28][29][30], and synthesis of chemicals [28][29][30][31][32][33]-because when coupled with a semiconductor photocatalyst, CQDs can provide with several advantages, including improved light harvesting ability, efficient usage of the full spectrum of sunlight, efficient charge carrier separation, stability, and hinder charge recombination. Figure 1 illustrates the various applications of CQDs in photocatalysis (left) and their competitive optical and structural properties during each photocatalytic procedure (right).…”