Carbon-Nanodot Solar Cells from Renewable Precursors

This is the peer reviewed version of the following article: Adam Marinovic, Lim S. Kiat, Steve Dunn, Maria-Magdalena Titirici, and Joe Briscoe, ‘Carbon-Nanodot Solar Cells from Renewable Precursors’, Chemistry and Sustainability, Vol. 10 (5): 1004-1013, March 2017, which has been published in final form at https://doi.org/10.1002/cssc.201601741. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.It has recently been shown that waste biomass can be converted into a wide range of functional materials, including those with desirable optical and electronic properties, offering the opportunity to find new uses for these renewable resources. Photovoltaics is one area in which finding the combination of abundant, low-cost and non-toxic materials with the necessary functionality can be challenging. In this paper the performance of carbon nanodots derived from a wide range of biomaterials obtained from different biomass sources as sensitisers for TiO2-based nanostructured solar cells was compared; polysaccharides (chitosan and chitin), monosaccharide (d-glucose), amino acids (l-arginine and l-cysteine) and raw lobster shells were used to produce carbon nanodots through hydrothermal carbonisation. The highest solar power conversion efficiency (PCE) of 0.36 % was obtained by using l-arginine carbon nanodots as sensitisers, whereas lobster shells, as a model source of chitin from actual food waste, showed a PCE of 0.22 %. By comparing this wide range of materials, the performance of the solar cells was correlated with the materials characteristics by carefully investigating the structural and optical properties of each family of carbon nanodots, and it was shown that the combination of amine and carboxylic acid functionalisation is particularly beneficial for the solar-cell performance.Peer reviewedFinal Accepted Versio

Fluorescent nanoparticles for sensing

Nanoparticle-based fluorescent sensors have emerged as a competitive alternative to small molecule sensors, due to their excellent fluorescence-based sensing capabilities. The tailorability of design, architecture, and photophysical properties has attracted the attention of many research groups, resulting in numerous reports related to novel nanosensors applied in sensing a vast variety of biological analytes. Although semiconducting quantum dots have been the best-known representative of fluorescent nanoparticles for a long time, the increasing popularity of new classes of organic nanoparticle-based sensors, such as carbon dots and polymeric nanoparticles, is due to their biocompatibility, ease of synthesis, and biofunctionalization capabilities. For instance, fluorescent gold and silver nanoclusters have emerged as a less cytotoxic replacement for semiconducting quantum dot sensors. This chapter provides an overview of recent developments in nanoparticle-based sensors for chemical and biological sensing and includes a discussion on unique properties of nanoparticles of different composition, along with their basic mechanism of fluorescence, route of synthesis, and their advantages and limitations

Enhancing Light Absorption and Charge Transfer Efficiency in Carbon Dots Through Graphitization and Core Nitrogen Doping

Single-source precursor syntheses have been devised for the preparation of structurally similar graphitic carbon dots (CDs), with (g-N-CD) and without (g-CD) core nitrogen doping for artificial photosynthesis. An order of magnitude improvement has been realized in the rate of solar (AM1.5G) H$_{2}$ evolution using g-N-CD (7950 μmolH2 (gCD)$^{−1}$ h$^{−1}$ ) compared to undoped CDs. All graphitized CDs show significantly enhanced light absorption compared to amorphous CDs (a-CD) yet undoped g-CD display limited photosensitizer ability due to low extraction of photogenerated charges. Transient absorption spectroscopy showed that nitrogen doping in g-N-CD increases the efficiency of hole scavenging by the electron donor and thereby significantly extends the lifetime of the photogenerated electrons. Thus, nitrogen doping allows the high absorption coefficient of graphitic CDs to be translated into high charge extraction for efficient photocatalysis.Oppenheimer PhD scholarship, Poynton PhD scholarship, Marie Curie postdoctoral fellowship, FRQNT postdoctoral fellowship, ERC Intersolar project, Christian Doppler Research Association (Austrian Federal Ministry of Science, Research and Economy and the National Foundation for Research, Technology and Development), OM

Chemically Induced Fluorescence Switching of Carbon-Dots and Its Multiple Logic Gate Implementation

[[sponsorship]]原子與分子科學研究所[[note]]已出版;[SCI];有審查制度;具代表性[[note]]http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Drexel&SrcApp=hagerty_opac&KeyRecord=2045-2322&DestApp=JCR&RQ=IF_CAT_BOXPLO

Synthesis and Photoluminescence Properties of MoS2/Graphene Hetero-Structure by Liquid Phase Exfoliation

Synthesis of MoS2/Graphene hetero-structure in single stage, liquid-phase exfoliation in 7:3 isopropyl alcohol /water mixture and its consequences on the photoluminescence behavior of MoS2 have been studied. Thus synthesized hetero-structure was characterized using UV-visible, micro-Raman spectroscopy, Transmission electron microscopy(TEM), and Dynamic Light Scattering (DLS) analysis. UV-Visible and micro-Raman analysis confirm improved exfoliation to the level of monolayer hetero-structure. The photophysical properties of the hetero-structure were analyzed using steady state and time resolved luminescence techniques. An enhanced photoluminescence observed in the case of hetero-structure probably due to increase in the defect sites or reduction in the rate of non-radiative decay upon formation of sandwiched hetero-structure. Applications of this hetero-structure for fluorescence live cell imaging carried out and the hetero-structure demonstrated a better luminescence contrast compared to its individual counterpart MoS2 in phosphate buffered saline (PBS)

Ligand-dependent transient absorption studies of hybrid polymer:CdSe quantum dot composites

In this work, fourier transform infra-red (FTIR), photoluminescence (PL), optical and transient absorption (UV-vis & TA) spectroscopies have been used to monitor charge transfer from excited conjugated polymer (MEH-PPV) to smaller sized (5-7 nm) monodispersive CdSe quantum dots (QD) prepared by the chemical route using different capping ligands as trioctyl phosphine oxide (TOPO) and oleic acid (OA). CdSe (OA) QD's (similar to 7 nm) owing to its relatively smaller surface energies compared with CdSe (TOPO) QD's (similar to 5 nm) shows lesser quenching capabilities within the MEH-PPV polymer matrix. These studies demonstrate dominance of respective processes of photoinduced Forster energy transfer between host polymer (donors) and guest CdSe nanocrystals (acceptors) in polymer:CdSe(OA) nanocomposites and charge transfer in polymer:CdSe(TOPO) nanocomposites. Due to limitations of our nanosecond laser flash photolysis apparatus, transient absorption signatures of positive polaron of MEH-PPV could not be detected since it exhibits characteristic absorption in the mid-IR region. However, signatures of transient corresponding to CdSe-* radical in the visible region was seen only when the sample was excited in the presence of polymer (MEH-PPV). A model has been proposed, which elucidate the possibility to modulate charge/energy transfer rate between polymer and semiconductor quantum dots using a suitable ligand-exchange process. The various characterization techniques used in this work provide an insight into the charge separation, charge accumulation and/or trapping of charge carriers for the better understanding of hybrid organic-inorganic photovoltaics

Editorial: Chemical reactions and catalysis for a sustainable future

Editorial on the Research Topic: Chemical reactions and catalysis for a sustainable futureDeveloping catalytic chemical processes for a sustainable future is a constant challenge involving different knowledge áreas (Sakakura et al., 2007; Yang et al., 2013; Götz et al., 2016; Tian et al., 2023; Yu et al., 2023). It requires multidisciplinary actions that include economic sectors, industry, society, and the environment (Lee et al., 2006; Corma et al., 2007; Naik et al., 2010; Ferreira Mota et al., 2022; Tafete and Habtu, 2023). Furthermore, catalytic chemical processes require constant evaluation to achieve greater sustainability, mainly when applied in industries or on a domestic scale (Chheda et al., 2007; Khodakov et al., 2007; Oh et al., 2016; Deng et al., 2023). Indeed, chemical catalysis is inherent in developing a sustainable future (Kondratenko et al., 2013; Deng et al., 2023). Chemical reactions are inseparable from our subject since they are applied in different processes, such as the preparation of fuels, food, drugs, and energy (Arcadi, 2008; Lima et al., 2022; Moreira et al., 2022; Sales et al., 2022; de Sousa et al., 2023; Faizan and Song, 2023; Nogueira et al., 2023). In this context, we include scientific research to help make these processes more sustainable. Moreover, consequently, it reduce the negative impact on the environment (Wang et al., 2023a; Zhu et al., 2023). Regarding chemical catalysis, reducing the amount of energy involved in the processes is fundamental (Roy et al., 2010; Yang et al., 2023a; Nogueira et al., 2023). This has a positive impact on reducing the use of polluting energy sources so that these systems can happen, such as the use of petroleum-derived fuels (Torborg and Beller, 2009; Catumba et al., 2023; Jafarian et al., 2023; Park and Kim, 2023). Furthermore, the greater need to use high temperature and pressure conditions increases energy consumption and, consequently, the production of waste that pollutes the environment (Singh et al., 2018; Djandja et al., 2023). Thus, chemical catalysis must seek to reduce the energy required for these processes, for example, in the design of robust catalysts (Yang et al., 2023b); The design of robust catalysts for industrial applications can be presented in different physical states, such as solid, liquid, or gaseous (Mariscal et al., 2016; Ferreira Mota et al., 2022; Issaka et al., 2023). The principle of sustainable functioning of these catalysts must include the formation of desired products (Centi et al., 2013). Be highly efficient in guiding molecules of reagents to the formation of desired products and eliminating the generation of unwanted waste (Li et al., 2023a; Li et al., 2023b). Another crucial factor for the design of sustainable catalysts must include their stabilization power, that is, whether the catalyst can be used repeatedly in the same reused process, minimizing the formation of polluting species and being economically viable (Centi et al., 2013; Wang et al., 2023b). In this way, the formation of sustainable reaction processes is the realization of catalytic systems on a large scale (Abbas-Abadi et al., 2023; Abuzeyad et al., 2023). This strategy makes it possible to reduce energy and polluting waste generated in the environment (Zhao et al., 2023). This fact also implies a decrease in energy use from oil and contributes to green chemistry practices (Goyal et al., 2008; Akram et al., 2023). Therefore, catalysis is different in advancing clean, renewable, and consequently sustainable technologies (Waseem et al., 2023; Zhang et al., 2023). In this context, catalysis is fundamental in producing fuel cells, which convert chemical energy into electrical energy in an environmentally sustainable way (Zhao et al., 2015; Gong et al., 2023). Likewise, catalysis is fundamental in producing biofuels from renewable sources such as biomass (Li et al., 2023c; Jiang et al., 2023; Yu et al., 2023).Peer reviewe

Multisensing Capability of MoSe₂ Quantum Dots by Tuning Surface Functional Groups

Several distinct surface-functionalized molybdenum diselenide (MoSe₂) quantum dots (QDs) were developed as chemosensors based on the fluorescent probe. The carboxylic-, amine-, and thiol-functionalized MoSe₂ QDs (MoSe₂/COOH, MoSe₂/NH₂, and MoSe₂/SH) were synthesized by tuning their surface with thiol-containing capping agents. These MoSe₂/COOH and MoSe₂/NH₂ QD sensors were implemented for the highly selective and sensitive detection of copper ion (Cu²⁺) and 2,4,6-trinitrophenol (TNP) with a lower detection limit of 4.6 and 45.3 nM, respectively. Similarly, the MoSe₂/SH QDs while coupled with gold nanoparticles showed excellent selectivity toward melamine (MA) with a lower detection limit of 27.7 nM. It is surprising to find that each functionalized QD exhibits a distinct sensing mechanism in the detection of Cu²⁺, TNP, and MA, based on metal-ion-induced fluorescence turn-on, electron transfer, and energy transfer suppression, respectively. Moreover, these MoSe₂ QD-based chemosensors were successfully utilized in real samples, confirming their propitious application

Unravelling the Multiple Emissive States in Citric-Acid-Derived Carbon Dots

Steady-state and time-resolved fluorescence spectroscopy techniques were used to probe multifluorescence resulting from citric-acid-derived carbon dots (C-dots). Commonly, both carboxyl-/amine-functionalized C-dots exhibit three distinct emissive states corresponding to the carbon-core and surface domain. The shorter-wavelength fluorescence (below 400 nm) originates from the carbon-core absorption band at ∼290 nm, whereas the fluorescence (above 400 nm) is caused by two surface states at ∼350 and 385 nm. In addition to three emissive states, a molecular state was also found in amine-functionalized C-dots. Time-resolved emission spectra (TRES) and time-resolved area normalized emission spectra (TRANES) were analyzed to confirm the origin of excitation wavelength-dependent fluorescence of C-dots. The surface functional groups on the C-dots are capable of regulating the electron transfer to affect the multifluorescence behavior. The electron transfer takes place from the carbon-core to surface domain by the presence of −COOH on the surface and <i>vice versa</i> for the case of −NH₂ present on the surface. To the best of our knowledge, this is the first report that the multiemissive states are probed in C-dots systems using TRES and TRANES analyses, and related fluorescence mechanisms are verified clearly