resumo
In this study, the morphology, size, and optical properties of carbon dots (CDs) synthesized at various temperatures (250, 300, 350 and 400 degrees C) are investigated, along with their incorporation into kappa-carrageenan (kappa-Cg)-based membranes. A simple, low-cost, and environmentally friendly method is proposed for synthesizing photoluminescent CDs using a single natural source precursor, the Arundo donax leaf. Through a systematic experimental approach we assess the influence of the synthesis conditions on the optical properties of the resulting CDs. The CDs, predominantly spherical with sizes ranging from 3.2 to 4.8 nm, exhibit an essentially graphitic structure. Surface functional groups, such as C 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 O and O-H, enhance their hydrophilicity. The CDs display strong blue-to-green fluorescence in aqueous solutions. When integrated into kappa-Cg-based films, the CDs influence the structural and morphological properties of the host matrix. These flexible, scalable, thermally stable, eco-friendly, and mechanically robust films demonstrate quantum yield values comparable to that in aqueous solutions, suggesting that the kappa-Cg matrix mantains the CDs' emission properties due to weak interactions, preserving electronic transitions. Additionally we develop a sun-actuated zero-energy dual-mode thermotropic device (TTDs) featuring kappa-Cg doped with CDs and 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) thermotropic ionic liquid. At 40 and 60 degrees C, this TTD operates as a dual-mode system with transmittance variation (Delta T) values of 10/8% and 13/10% at 550/1000 nm, respectively. Upon addition of silver islands the surface plasmon resonance effect (SPRE)-mediated TTD offers a three-mode operation (a bright hot mode (visible and NIR admitted), a semi-bright warm mode (visible and NIR semi-blocked), and a semi-dark semi-cool mode (visible and NIR further semi-blocked) with Delta T values of 42/40% and 58/55% at 40 and 60 degrees C, respectively), and stable performance over multiple cycles. Overall, our findings highlight the potential of kappa-Cg matrices for developing luminescent materials with stable and predictable optical properties for advanced optoelectronics and sensing applications.
palavras-chave
GREEN SYNTHESIS; QUANTUM DOTS; SMART WINDOWS; NITROGEN; FLUORESCENCE; ELECTROLYTE; EMISSION; GRAPHENE; LAYERS
categoria
Chemistry; Energy & Fuels; Materials Science
autores
Nunes, SC; Duarte, TAG; Pereira, RFP; Fu, L; Ferreira, RAS; Almeida, P; Bermudez, VD
nossos autores
Lianshe Fu
Investigador JúniorProjectos
Solar-Powered Smart Windows for Sustainable Buildings (SOLPOWINS)
Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
The work was funded by projects SOLPOWINS - Solar-Powered Smart Windows for Sustainable Buildings (PTDC/CTM-REF/4304/2020), financed by FCT and FEDER, NORTE2020, and A-MOVER - "Mobilizing Agenda for the Development of Products & Systems towards an Intelligent and Green Mobility", operation no. 02/C05-i01.01/2022.PC646908627-00000069, approved under the terms of the call no. 02/C05-i01/2022 - Mobilizing Agendas for Business Innovation, financed by European funds provided to Portugal by the Recovery and Resilience Plan (RRP), in the scope of the European Recovery and Resilience Facility (RRF), framed in the Next Generation UE, for the period from 2021-2026. The authors acknowledge funding from CQ-VR (UIDB/00616/2020 (https://doi.org/10.54499/UIDB/00616/2020)) and UIDP/00616/2020 (https://doi.org/10.54499/UIDP/00616/2020), CQ-UM (UIDB/00686/2020 (https://doi.org/10.54499/UIDB/00686/2020) and UIDP/00686/2020 (https://doi.org/10.54499/UIDP/00686/2020)), CICECO-Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020, and LA/P/0006/2020) and Instituto de Telecomunicacoes (UIDB/50008/2020 and UIDP/50008/2020), financed by National funds through the FCT/MEC (PIDDAC), and when appropriate co-financed by FEDER under the PT2020 Partnership through European Regional Development Fund (ERDF) in the frame of Operational Competitiveness and Internationalization Programme (POCI), and FibEnTech-UBI (UIDB/00195/2020 and https://doi.org/10.54499/UIDB/00195/2020), financed by National funds through the FCT/MCTES (PIDDAC). S. C. Nunes acknowledges FCT for Assistant Research contract ((2020-00805.CEEIND; https://doi.org/10.54499/2020.00805.CEECIND/CP1625/CT0001) in the scope of Scientific Employment Stimulus. R. F. P. Pereira acknowledge FCT for the contract in the scope of Decreto-Lei 57/2016 (https://doi.org/10.54499/DL57/2016/CP1377/CT0050) and for the Assistant Research contract (2023.07994.CEECIND).