Solar-powered water evaporation shows prominent advantages in extracting fresh water. To achieve high photothermal-conversion efficiency, development of efficient solar evaporators is highly pursued. Here, a new solar evaporator made of a carbonized carbon dot-modified starch aerogel (C-CDSA) was developed. Benefiting from the introduced carbon dots (CDs) that promoted the polymerization and carbonization of starch chains, C-CDSA exhibited a three-dimensional (3D) interconnected porous structure with a larger pore size and thinner pore wall as well as higher porosity. Due to the low carbonization temperature (270 °C) and the feature of CDs with rich oxygenated groups, a higher content of oxygenated groups was preserved in C-CDSA, which not only ensured the super hydrophilicity but also contributed to water activation. By virtue of the structural and compositional advantages, C-CDSA showed enhanced light harvesting, desired thermal insulation, fast water transportation and superiority in reducing the water evaporation enthalpy. Therefore, the designed low-cost and eco-friendly C-CDSA not only exhibited a high evaporation rate of 2.29 kg m⁻² h⁻¹ with an energy conversion efficiency of 93.5% under 1.0 sun irradiation, but also showed stable water evaporation performance in acidic, alkaline, high-salt (10 wt%) and organic pollutant solutions, holding great promise for practical solar water evaporation applications.

A controlled and effective strategy is offered for synthesizing carbon dots (CDs) with dual photoluminescence peaks and reliable fluorescence ratiometric pH sensing.

A novel solar-heating superhydrophobic sorbent system created by the in situ chemical reaction of carbon dots with commercial porous sponge has been developed for the high-speed sorption of viscous crude oil from a seawater surface.

Fluorescent resonance energy transfer between the carbon quantum dots and Rhodamine B can be used to enhance Fe³⁺ detection.

A simple and low-cost approach is developed, by which nitrogen-doped carbon dots (NCDs) with a negative potential are assembled inside the mesoporous channels of SBA-15 via capillary force. The unique confined microenvironment leads to a strong interaction between confined NCDs and the inner surface of SBA-15, thus effectively avoiding the aggregation of NCDs. The resultant composite (NCDs-in-SBA-15) exhibits blue fluorescence similar to the NCD aqueous solution, and shows excellent structural, thermal and photostability. Solid NCDs-in-SBA-15 still emits fluorescence even after heat treatment at 400 °C under ambient atmosphere. In addition, NCDs-in-SBA-15 possesses remarkable resistance to acid/alkali solvents. Furthermore, NCDs-in-SBA-15 shows superior selectivity and adsorption capacity to Fe³⁺. The facile approach and these advantageous performances could make CDs meet the requirements of fluorescent materials in the solid state and then have wider applications.