Engineering wood with synergistic salt mitigation and microbial suppression for efficient and durable solar desalination

• Achieves 1.44 kg m −2 h −1 evaporation rate and 92 % efficiency in 3.5 wt % brine. • Synergistic salt rejection and biofilm resistance ensure long-term stability. • Anisotropic heat confinement and rapid water supply sustain evaporation. • Carbon microspheres enhance light absorption for efficient heating. Interfacial solar evaporation offers an energy-efficient and sustainable alternative to conventional desalination and wastewater treatment technologies. Ensuring long-term operational stability necessitates effective thermal management, robust salt rejection capabilities, and reliable biofouling resistance. Herein, we develop a multifunctional wood-derived solar absorber via p-toluenesulfonic acid monohydrate (p-TsOH)-catalyzed hydrothermal carbonization of natural forest wood. This dual-phase process produces light-trapping carbon microspheres while simultaneously restructuring the hierarchical microarchitecture. The engineered absorber achieves exceptional performance metrics—an evaporation rate of 1.44 kg m −2 h −1 and a solar-thermal conversion efficiency of 92% under 1 sun illumination in 3.5 wt% NaCl solution—attributed to optimized thermal localization through anisotropic heat confinement. Notably, the carbonized matrix maintains an interconnected porous network with enhanced hydrophilicity, establishing efficient hydraulic pathways that facilitate rapid salt ion diffusion from the evaporation interface, thereby preventing salt crystallization. Furthermore, in situ generated phenolic compounds and furfural derivatives impart intrinsic antibacterial properties by inhibiting microbial ATP synthesis and compromising membrane integrity, thereby ensuring sustained operational stability. This integrated approach demonstrates that p-TsOH-delignified wood absorbers present a scalable platform for high-performance desalination, combining efficient solar utilization, autonomous salt rejection, and microbial suppression within a carbon-negative material system, advancing sustainable water purification technologies.