Kill two birds with one stone: In-situ carbon dots-integrated rGO achieves ultra-efficient solar steam generation driving artificially hydrologic cycle towards soil remediation

Solar-driven interfacial evaporation (SIE) offers a sustainable solution towards global water-energy-environment crises. Graphene as an advanced photothermal material represents a promising candidate for SIE to generate steam rapidly for multi-functional applications. However, an inherent trade-off between the π-conjugation and the hydrophilicity seriously hinders the SIE performance of graphene-based materials. Herein, we propose an innovative route to synchronously elevate both the hydrophilicity and the π-conjugation by in-situ growth of carbon dots on reduced graphene oxide (CDs-rGO). Fundamentally, the introduction of CDs shortens the bandgap and brings fluorescence resonance energy transfer effect, achieving an outstanding photothermal conversion efficiency of 99.3 %. Moreover, the abundant oxygen-containing groups of CDs ensure effective water activation of CDs-rGO, further reducing the solid-liquid interface thermal resistance and evaporation enthalpy of water. The corresponding three-dimensional porous aerogel demonstrates an unprecedentedly high water evaporation rate of 8.25 kg m −2  h −1 under 1 sun irradiation. Leveraging the ultra-efficient solar steam generation, a SIE-driven artificially hydrologic cycle system has been creatively designed for heavy metal-contaminated soil remediation, illustrating an impressive cobalt removal efficiency of 60.1 %. This work highlights the crucial roles of π-conjugation in elevating the solar-to-heat conversion and hydrophilicity in promoting water activation, and offers novel insights into expanding SIE to soil remediation.