Modulating Photothermal Properties of Carbon Dots through Nitrogen Incorporation Enables Efficient Solar Water Evaporation

Ita Rahmawati, Indriyati, Fitri A. Permatasari, Muhammad A. Irham, Mohamad Insan Nugraha, Thomas D. Anthopoulos, Ferry Iskandar

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


As a new family in carbon nanomaterials, carbon dots (CDs) are potential candidates for solar water evaporator, owing to their cost-effectiveness, non-toxicity, high solubility, and tunable optical properties. Despite such potentials, however, CDs mainly absorb solar spectrum in the ultraviolet region while their absorption in the visible region is limited, the characteristics that hinder their functionality in generating steam from solar energy. Herein, the optical and photothermal properties of CDs, derived from urea and citric acid, can be modulated by controlling their surface stoichiometry through varying the molar ratio of the precursors. Our approach is simple, fast, and highly scalable by utilizing a microwave irradiation technique. We found that increasing the nitrogen content results in broadening of the absorption spectra into the visible region due to more functional groups introduced on the CD surface that reduce the band gap, as confirmed both by X-ray photoelectron spectroscopy and theoretical calculation. Employing the CDs as photothermal materials in the volumetric solar evaporator, we demonstrate a remarkable evaporation efficiency of up to 70% along with a volumetric evaporation rate of 1.11 kg m–2 h–1 under 1 sun illumination, superior to direct bulk water heating. Furthermore, the CDs show excellent durability and stability, as demonstrated by their stable evaporation rate for 10 days, with no significant decrease in the optical and photothermal properties. This finding provides a pathway to design and functionalize CDs with controllable optical and photothermal properties for an efficient solar evaporation system.
Original languageEnglish (US)
JournalACS Applied Nano Materials
StatePublished - Feb 16 2023

Bibliographical note

KAUST Repository Item: Exported on 2023-02-21
Acknowledged KAUST grant number(s): OSR-2018-CARF/CCF-3079, OSR-2019-CRG8-4095
Acknowledgements: This work was fully supported by the Indonesian Endowment Fund for Education and the Indonesian Science Fund through the International Collaboration RISPRO Funding Program grant no. RISPRO/KI/B1/KOM/11/4542/2/2020. I.R. and F.A.P. would like to thank the Ministry of Finance, Indonesia, through Endowment Fund for Education (LPDP) for their master’s and doctoral scholarship. I. acknowledges Degree by Research (DBR) Program from the National Research and Innovation Agency (BRIN) for the doctoral scholarship. M.A.I. is supported by the PMDSU Program of the Ministry of Education and Culture, Indonesia. M.I.N. and T.D.A. acknowledge the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) for funding under award no: OSR-2018-CARF/CCF-3079 and OSR-2019-CRG8-4095. The authors acknowledge the facilities and technical support from the Advanced Characterization Laboratories Serpong, National Research and Innovation Agency through E-Layanan Sains BRIN.


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