WC/C Composite as an Efficient Photothermal Material for Solar-Driven Seawater Evaporation

Solar-driven interfacial water evaporation has been recognized as an effective measure to address freshwater scarcity. Photothermal materials lie at the core of this process and have been extensively studied. However, conventional carbon-based materials typically suffer from high thermal emissivity, leading to significant heat loss. Here, we report a tungsten carbide/carbon composite polyvinyl alcohol hydrogel evaporator (PWC) for solar-driven interfacial seawater evaporation. Specifically, a tungsten carbide/carbon (WC/C) composite was synthesized via a straightforward one-step molten salt coating method and exhibited a remarkable photothermal conversion efficiency of 67.1%, attributed to the plasmon resonance absorption effect of WC nanoparticles. When incorporated into a polyvinyl alcohol (PVA) hydrogel via a physical-chemical dual-crosslinking strategy, the resulting PWC evaporator achieved a high evaporation rate of 2.99 kg m^-2 h^-1 and a conversion efficiency of 90.9% in a 5 wt% NaCl solution under 1 kW m^-2 illumination. In addition, the evaporator can purify seawater and effectively remove a variety of organic dyes. This study provides a viable strategy for a sustainable freshwater supply.