The lack of fresh water resources is attracting concern worldwide. Recently, to address this global issue, researchers proposed the heat localization concept for interfacial solar seawater desalination in 2014. Since then, interfacial solar steam generation (ISSG) devices have attracted much attention, due to their potential for achieving highly enhanced optical‐thermal conversion through a single interface as compared with traditional solar seawater desalination. To date, the promising prospect of ISSG systems in seawater desalination has stimulated the rapid development of solar desalination technology based on heat localization. To comprehensively recognize ISSG devices and acquire more insights into their design associated with biological relevance, efficiency improvement, and applications, this review summarizes the progresses and prospects of ISSG devices in relation to the evolution of advanced materials, the engineering architecture, the collaborative application, and the current challenges.

Interfacial solar steam generation (ISSG) has received increasing attention in both industry and academia, and is considered a method with great potential for wastewater treatment and desalination. These practical applications require materials that fulfil several requirements: being low cost, being scalable in terms of processing, being environmentally friendly, and having a high, stable optical–thermal conversion efficiency of solar vaporization. Currently, biomass materials show very promising prospects for ISSG systems. Here, it is observed that bamboo charcoal (BC) possesses a series of unique advantages that make it a highly efficient ISSG device. The broadband light absorption and the arched and porous structural features of BC fulfil all the basic requirements of an ISSG device in localized heating, heat management, and water supply. The self‐contained arched BC device demonstrates high evaporation efficiency (84% under 1 sun radiation) and superb stability under strongly acidic, strongly alkaline, and intense light environment conditions. More importantly, the porous BC device can provide stable fresh water production that simultaneously promotes the purification of water via evaporation by heating. Finally, the low cost, environmentally sustainable, mechanically robust, and long‐term stable BC device is a potential opportunity for wastewater treatment and desalination in underdeveloped areas.

Solar-driven interfacial steam generation (SDISG), as an emerging green and renewable approach to overcome water shortage, is very suitable for remote locations, developing countries, and disaster zones because it does not require an additional energy supply. However, the traditional metal-based and carbon-based absorbers always suffered from fragility (or rigidity) and the complex preparation process, which dramatically inhibited their transportation and installation in areas with poor infrastructure. Therefore, there is an urgent need to develop a universal method to fabricate flexible solar evaporators. Herein, a novel solar evaporator that integrates a flexible matrix (Cu mesh or textile) and a hierarchical Fe-MOF-74 photothermal absorber component is perfectly prepared for the rapid and efficient SDISG. Notably, the results show that Fe-MOF-74-based flexible textile matrix composites exhibit outstanding light absorption (83.81%), low thermal conductivity (0.1730 W/m K), super hydrophilic properties (within 50 ms, the contact angle is close to 0°), excellent salt resistance, high evaporation rate (1.35 kg/m2 h), and photothermal conversion efficiency (η is 81.5% under one sun, stable for 30 days). Owing to the flexibility, recyclability, and above-mentioned excellent performance, the prepared hierarchical Fe-MOF-74-based flexible composite systems are more practical for transportation, large-scale production, and stable and efficient applications. As a result, this work offers new insight into the future development of the combination of a MOF-based photothermal absorber and flexible substrates, as well as for the application of interfacial solar seawater desalination, and provides a new reference for other applications.

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Thermoregulating textiles as an emerging approach to promote people comfort have attracted significant attention in recent years. However, a simple, efficient, and cost‐effective strategy that can autonomously absorb sunlight without extra power supply to warm the human body is lacking. Herein, a novel nanogradient MoOx absorber (NMOA) on flexible polymers and wearable fabrics for personal passive heating is successfully fabricated via a simple one‐step reactive sputtering technique. The surface steady‐state temperatures of the NMOA coated on polymers and fabrics reach 78 and 90 °C under one sun illumination, confirming efficient solar thermal conversion, resulting from the superior absorption of NMOA. More importantly, the heating property of NMOA is on par with those of silver nanowire or carbon nanotube‐coated textiles that use the Joule heating effect applied with a high voltage supply. It is noteworthy that achieving a high temperature at a low voltage is difficult, and hence the use of NMOA presents significant advantages. Due to the outstanding spectrally selective property of NMOA, the textile enables a 11 °C temperature enhancement in a cold environment (2 °C). Together with its superior light‐absorbing ability and excellent adhesion nature, the NMOA could be very promising in thermoregulating flexible and wearable applications.

Advances in flexible and wearable energy-related devices increase the need for highly efficient, low-cost, ultrathin solar selective absorber coatings (SSACs). Herein, the fabrication of nanogradient WO x -based SSACs with excellent properties, including a superior solar absorptance of 0.93, an outstanding thermal robustness of up to 300 C, and substrate independence, is reported. More importantly, the thickness of WO x -based SSACs is only approximately 100 nm, which is substantially thinner than all other reported SSACs. These features arise from the two intrinsically absorptive WO x layers on a thin nanoplasmonic W layer. The deposition process is based on self-doped reactive sputtering via limited tungsten oxidation due to a small amount of oxygen. The WO x -based SSACs on a flexible polyimide sheet demonstrate stable performance, strong adhesion, and bendable nature. The proposed self-doped fabrication process provides a new way to design cost-effective ultrathin SSACs to meet the demand for large-scale flexible energy harvesting and supply applications.

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