Nitrogen-doped microporous graphite-enhanced copper plasmonic effect for solar evaporation

Water scarcity is a global challenge, and solar evaporation technology offers a promising and eco-friendly solution for freshwater production. Photothermal conversion materials (PCMs) are crucial for solar evaporation. Improving photothermal conversion efficiency and reducing water evaporation enthalpy are the two key strategies for the designing of PCMs. The desired PCMs that combine both of these properties remain a challenging task, even with the latest advancements in the field. Herein, we developed copper nanoparticles (NPs) with different conjugated nitrogen-doped microporous carbon coatings (Cu@C-N) as PCMs. The microporous carbon enveloping layer provides a highly efficient pathway for water transport and a nanoconfined environment that protects Cu NPs and facilitates the evaporation of water clusters, reducing the enthalpy of water evaporation. Meanwhile, the conjugated nitrogen nodes form strong metal-organic coordination bonds with the surface of copper NPs, acting as an energy bridge to achieve rapid energy transfer and provide high solar-to-vapor conversion efficiency. The Cu@C-N exhibited up to 89.4% solar-to-vapor conversion efficiency and an evaporation rate of 1.94 kg m-2 h-1 under one sun irradiation, outperforming conventional PCMs, including carbon-based materials and semiconductor materials. These findings offer an efficient design scheme for high-performance PCMs essential for solar evaporators to address global water scarcity. It has been proved that conjugated nitrogen-doped carbon which bridges the energy transmission between the plasmonic metal-surface and carbon plane via the formed metal-organic coordination bond, could enhance photothermal conversion efficiency in Cu-carbon composites. Combined with the desired water-cluster evaporation effect in microporous structure, the obtained Cu-carbon composites exhibit a high water-evaporation rate. image