Realizing an evaporation rate of 4.31 kg·m−2·h−1 and an energy efficiency of 97.88% by assembling efficient mass transfer channels and full-spectrum solar-absorbing semiconductors into Janus evaporators

Janus evaporators achieve an energy utilization efficiency of 97.88%. • Janus evaporators demonstrate evaporation rates of 4.31 kg·m −2 ·h −1 . • Janus evaporators exhibit excellent long-term stability for 12 days. • Janus evaporators produce 18.53 kg·m −2 of fresh water per day. Solar interfacial evaporation is an emerging sustainable freshwater production technology. However, its effectiveness is often hindered by insufficient heat and mass transfer, the inherently high enthalpy of vaporization of water, and salt management issues. This study proposes a Janus-type photothermal semiconductor@biomass porous hydrogel evaporator to achieve high-rate and highly energy-efficient solar interfacial evaporation. Efficient biomass-based water transport channels were constructed through a microphase separation process and in-situ ionic crosslinking. The hydrophilic microenvironment of polar polymers was utilized to regulate the aggregation state of water molecules and reduce the equivalent enthalpy of vaporization. The Janus evaporator was assembled from photothermal semiconductors (tellurium nanoparticles) and biomass porous hydrogels to synergistically improve evaporation efficiency. Under one sun illumination, the evaporator achieved evaporation rates of 4.31 kg·m −2 ·h −1 in deionized water and 3.10 kg·m −2 ·h −1 in 3.5% simulated seawater, with an energy efficiency of 97.88%. Furthermore, due to the salt diffusion facilitated by the porous structure, it exhibited stable salt tolerance in simulated seawater with a high salinity of 10%. Outdoor natural seawater desalination experiments further confirmed its water production capacity and long-term stability, and the desalinated water quality met drinking water standards. This work provides a novel and forward-looking strategy for designing environmentally friendly, efficient, and stable solar evaporators.