Charge transfer mediated photoluminescence enhancement in carbon dots embedded in TiO2 nanotube matrix

Babusenan, Anu; Pandey, Beauty; Roy, Somnath C.; Bhattacharyya, Jayeeta

doi:10.1016/j.carbon.2020.01.097

Cited by 22 publications

(6 citation statements)

References 42 publications

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“…A variety of oxygen‐containing functional groups exits on the surface of CDs, such as typical ‐OH (≈3424 cm −1 , ≈1073 cm −1 , it can mostly be removed by annealing, i.e., annealed CDs), ─C≐O (≈1708 cm −1 ), and C─O─C (≈1175 cm −1 ) revealed by FTIR (Figure 1e). [ 32,33 ] Corresponding XPS full‐spectrum data also reveals that the percentage of O in the annealed CDs decreases from 20.4% to 12.3% while C increases from 79.6% to 87.7% (Figure 1f); these O reductions are mainly attributed to the decomposition of C─O (from 42.3% to 19.9% at 286.4 eV), [ 34,35 ] C≐O (from 9.5% to 4.8% at 288.2 eV), [ 36,37 ] and O─C≐O (from 8.1% to 0% at 288.8 eV) [ 35,37 ] decomposition of the three oxygen‐containing functional groups (Figure 1g); the same trend is demonstrated in the corresponding O 1s fine spectra, especially C≐O at 530.4 eV [ 38,39 ] and O─C≐O at 531.4 eV (Figure 1h). [ 40,41 ] Some of the oxygen‐containing functional groups containing H are also verified by their corresponding 1 H‐NMR (Figure S2, Supporting Information), including ─COOH at 10.28 ppm, ─CHO at 9.49 ppm, and ─OH at 2.06 ppm.…”

Section: Resultsmentioning

confidence: 98%

Carbon Dots as Ligand Operons to Expand Cluster Size Distribution for High Load‐bearing Liquid Superlubricity

Liang,

Liu,

Yin

et al. 2024

Adv Funct Materials

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Adding additives (e.g., carbon dots, CDs) to liquid lubricants is an effective method for enhancing their load‐bearing capacity and friction reduction. However, it is challenging to simultaneously impart high load‐bearing capacity and superlubricity for them (e.g., ionic liquid analogs, ILAs) through this strategy due to strong Coulombic interactions. With CDs as a competing ligand operon, the cluster size distribution can be expanded, conferring superlubricity with ultrahigh load‐bearing capacity (>705 MPa, the highest value of CDs‐based superlubricious materials thus far) for CDs/ILAs. In particular, methodologies such as Raman, 1H‐NMR, fourier transform infrared spectroscopy, and laser particle size analysis are employed to characterize the evolution of their H‐bonding interactions and particle size distribution. CDs can act as competing ligands and enable CDs/ILAs to form systems with ultra‐low coefficient of friction and wear consisting of a mixture of large and small clusters. The mixed and expanded size clusters facilitate the reduction of the viscosity for CDs/ILAs under shear, thereby reducing the interfacial shear resistance during superlubricity, while the CDs within them efficiently transfer the normal bearing loads. The progress is made from the perspective of cluster particle size distribution rather than individual additive properties, providing a new avenue for designing ILAs‐based superlubricious materials.

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Section: Resultsmentioning

confidence: 98%

Carbon Dots as Ligand Operons to Expand Cluster Size Distribution for High Load‐bearing Liquid Superlubricity

Liang,

Liu,

Yin

et al. 2024

Adv Funct Materials

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“…The valence band edge (VBE) is the point of intersection between the straight-line fits to the valence band and core-level spectra. 35 The VBE of 5BTBNNδ is located at 2.28 eV, which is 0.31 eV greater than the VBE (1.96 eV) of the 5BTBNN sample. This result suggests that there is a shift in the VBE position to higher energy upon cationic vacancy creation in the 5BTBNNδ sample.…”

Section: Optical Propertiesmentioning

confidence: 84%

“…The corresponding plots are shown in Figure a,b. The valence band edge (VBE) is the point of intersection between the straight-line fits to the valence band and core-level spectra . The VBE of 5BTBNNδ is located at 2.28 eV, which is 0.31 eV greater than the VBE (1.96 eV) of the 5BTBNN sample.…”

Section: Resultsmentioning

confidence: 99%

Cationic Vacancies Induced Enhanced Light Absorption with Controlled Leakage Current in Perovskite Ferroelectric Oxides

Sarath,

Murugavel

2024

ACS Appl. Eng. Mater.

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Visible-light-absorbing ferroelectric perovskite materials have shown promising potential in energy-harvesting applications. However, most of the ferroelectric systems have a large band-gap. The attempts to reduce their band-gap resulted in a large leakage current, which undermines their ferroelectric characteristics. In this study, traditional large-band-gap ferroelectric BaTiO3 (BTO) is modified to show a tunable band-gap capable of visible-light absorption with better leakage current characteristics. This is achieved by incorporating the cationic/anionic vacancies through transition metal Nb and Ni ion substitutions. Here, a comparative study of two BTO-based compositions having differences in the concentration of oxygen and cationic vacancies by varying the donor (Nb)–acceptor (Ni) doping concentration is carried out. Interestingly, the results show that the sample having more cationic vacancy concentration exhibits large band-gap reduction, enhanced light absorption, low leakage current magnitude, better ferroelectric hysteresis loop, and switchable photovoltaic response. Notably, this study unveils that oxygen defects are not a necessary condition for band-gap tuning. Overall, the present work opens a pathway to tune the optical band-gap without deteriorating the ferroelectric properties by controlling donor–acceptor dopant concentration.

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“…The hydrothermal synthesis method also enables CQDs to be directly synthesized onto photoanodes as sole photosensitizers. Other methods have been used to adhere CQDs to photoanodes, such as drop-casting, but yield poor adsorption and stability. , Zhang et al synthesized CQDs directly onto a TiO 2 photoanode via an in situ hydrothermal reaction of CA and ethanediamine with an immersed TiO 2 -coated photoanode . A CQD thin-film coating formed homogeneously on the porous TiO 2 layer, comprising spherical nanostructures with 2–6 nm particles that did not block the TiO 2 pores.…”

Section: Synthesis Methods For Cqdsmentioning

confidence: 99%

Carbon-Based Quantum Dots for Photovoltaic Devices: A Review

Kim

Dash

Kumar

et al. 2021

ACS Appl. Electron. Mater.

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Interest in carbon quantum dots (CQDs) has recently boomed due to their potential to enhance the performance of various solar technologies as nontoxic, naturally abundant, and cleanly produced nanomaterials. CQDs and their other variations, such as nitrogen-doped carbon quantum dots (NCQDs) and graphene quantum dots (GQDs), have improved the performance of luminescent solar concentrators (LSCs) and photovoltaic (PV) cells due to their excellent optical properties. As fluorophores in LSCs, CQDs are mostly transparent to visible light and have absorption/re-emission spectra that can be easily controlled. The outstanding optical properties of CQDs make them promising materials to replace expensive, heavy-metal-based fluorophores. Various CQDs have also been used as or doped into the photoanode, counter electrode, hole transport layer (HTL), and electron transport layer (ETL) of dye-sensitized solar cells (DSSCs), organic solar cells (OSC), perovskite solar cells (PSCs), and other PV cell configurations. The addition of CQDs into the various solar cell components has reduced electron recombination, increased charge density, and boosted electron mobility, improving the performance of the PV cells. Enhancing the power conversion efficiency (PCE) of photovoltaic devices is essential in propagating green energy technology. Thus, CQDs offer an affordable, safe, and environmentally friendly method to advance photovoltaic performance.

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Charge transfer mediated photoluminescence enhancement in carbon dots embedded in TiO2 nanotube matrix

Cited by 22 publications

References 42 publications

Carbon Dots as Ligand Operons to Expand Cluster Size Distribution for High Load‐bearing Liquid Superlubricity

Carbon Dots as Ligand Operons to Expand Cluster Size Distribution for High Load‐bearing Liquid Superlubricity

Cationic Vacancies Induced Enhanced Light Absorption with Controlled Leakage Current in Perovskite Ferroelectric Oxides

Carbon-Based Quantum Dots for Photovoltaic Devices: A Review

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