Biomass-derived carbon quantum dot: "On-off-on" fluorescent sensor for rapid detection of multi-metal ions and green photocatalytic CO2 reduction in water

Author(s)

Raja, Sebastian ; da Silva, Gelson T. S. T. ; Anbu, Sellamuthu ; Ribeiro, Caue ; Mattoso, Luiz H. C.

• Document type: Journal article
• Source: BIOMASS CONVERSION AND BIOREFINERY; v. N/A, p. 13-pg., 2023-05-02.

Abstract

We have developed carbon quantum dots (CQDs) with excellent photoluminescence (PL) properties from macauba (Acrocomia aculeate) fibers; a widely available cellulosic biomass species of palm trees in South America. As-prepared CQDs showed quasi-spherical morphology with high aqueous solubility and strong excitation-dependent fluorescence behaviour. Interestingly, the CQDs display fluorescence 'turn-off' response with excellent sensitivity toward multi-metal ions including Fe3+, Cu2+ and Hg2+ with very low detection limits of 0.69 mu M, 0.99 mu M, 0.25 mu M, respectively. Notably, ascorbic acid (AA) induced a change in the (turn-off) fluorescence of Fe3+-CQDs, which caused an almost 70% revival of fluorescence (turn-on) by displacing Fe3+ ions. We have also harnessed CQDs as the visible-light-induced photocatalyst to reduce CO2 in water. Especially, the CQDs efficiently promote the photocatalytic reduction of CO2 into methane (CH4) with an evolution rate of 99.8 nmol/g at 436 nm in aqueous conditions. This indicates that the CQDs provide abundant active sites for CO2 adsorption and thus enhance the separation and migration of photo-induced charge carriers that efficiently reduce CO2 into CH4 without any co-catalyst in 100% water. (AU)

• FAPESP's process: 18/01258-5 - Novel chemical catalytic and photocatalytic processes for the direct conversion of methane and CO2 to products
• Grantee: José Maria Correa Bueno
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 13/07296-2 - CDMF - Center for the Development of Functional Materials
• Grantee: Elson Longo da Silva
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 17/22017-3 - Near - infrared (NIR) cellulose nanocrystals (NIR - CNC) for cellular bioimaging
• Grantee: Raja Sebastian
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 15/00094-0 - Chemical modifications of cellulose nanowhiskers
• Grantee: Raja Sebastian
• Support Opportunities: Scholarships in Brazil - Post-Doctoral