Solar-driven steam generation is anticipated as one of the most promising and inventive technologies to address the primitive issues of water shortage. Although extensive attempts have been made to develop highly efficient solar steam generators, hindrances are faced to integrate all desired functions in a single evaporating system. Herein, we designed semiconductive in situpolymerized MnO 2 nanowires/chitosan (SPM-CH) hydrogels as flexible, built-in, vertically aligned, macropore-based water channels (∼0.5 μm pore size) for enhanced solar water generation (17.02 kg m −2 in 1 day). The nonradiative relaxation-dependent defect engineering of SPM-CH hydrogel promotes more lattice vibrations, and its polymeric network endorses the formation of enhanced intermediate water clusters for vapor generation. The self-floating and salt-resistant device possesses an excellent evaporation rate (1.78 kg m −2 h −1 ) during a single sunny day along with efficient solar energy conversion efficiency (90.6%) under 1 sun intensity, good solar absorption (94%), and good compressing flexibility (42% compressive strain). Moreover, COMSOL Multiphysics simulations of SPM-CH hydrogels under experimental conditions reveal its superior centralized heat accumulation within the top-interface matrix. The single-step execution for a freshwater supply purified from various contaminations including industrial wastewater and oil-emulsified water shows its potential as a reusable device toward real-life applications.

Solar‐powered water evaporation is a primitive technology but interest has revived in the last five years due to the use of nanoenabled photothermal absorbers. The cutting‐edge nanoenabled photothermal materials can exploit a full spectrum of solar radiation with exceptionally high photothermal conversion efficiency. Additionally, photothermal design through heat management and the hierarchy of smooth water‐flow channels have evolved in parallel. Indeed, the integration of all desirable functions into one photothermal layer remains an essential challenge for an effective yield of clean water in remote‐sensing areas. Some nanoenabled photothermal prototypes equipped with unprecedented water evaporation rates have been reported recently for clean water production. Many barriers and difficulties remain, despite the latest scientific and practical implementation developments. This Review seeks to inspire nanoenvironmental research communities to drive onward toward real‐time solar‐driven clean water production.

Solar‐driven interfacial steam generation has emerged as an innovative technique for seawater desalination due to its high photothermal conversion efficiency and potential industrial applications. Herein, a superior interfacial heat accumulation structure composed of semiconductive in situ polymerization (polypyrrole) of nickel foam (IPNF) is reported. The IPNF photothermal layer is assembled with superhydrophilic polyurethane substrate for synchronous water transport and excellent thermal insulation. The 2D ultrablack mesh induces multiple incident rays within the diffused polymerized surface, which allows omnidirectional solar absorption (88.5 %) and intensifying heat localization (49.5 °C @ 1 sun). The state‐of‐the‐art evaporation performances reveal that the integrated IPNF solar evaporator exhibits an excellent evaporation rate (1.74 kg m−2 h−1) and solar‐to‐vapor conversion efficiency (90% excluding heat losses) under 1 kW m−2 solar intensity. Besides this, the long‐term evaporation experiments show negligible discrepancy under seawater conditions (13.27 kg m−2/8 h under 1 kW m−2) and engrain its functioning potential for multimedia and salt rejection (3.2 g × NaCl/240 min). More importantly, herein, insights into different water states in the polymeric network systems during solar‐driven evaporation are provided. This work shows a significant potential to generate freshwater excluding heavy metals and other oil emulsions for industrial applications.

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