harvested and converted into heat for steam generation. [3] Because the existing ions, organics, and bacteria can be separated in the cost-effective and environmentally friendly process, solar energy-driven water evaporation is considered as a highly promising technology to purify water. [3b,4] Conventional water steam generation systems require many optical concentrators to achieve sufficiently high temperatures for heating water, low efficiency and high investment are the shortcomings. [3b] In this regard, recent studies focused on the localized heating of interfacial water based on photothermal materials with effective light absorption and light-to-heat conversion capabilities. [5] Nanoparticles such as gold, [6] titanium sesquioxide, [7] and alumina [8] were proposed for steam generation and water purification, but the low chemical stability, high cost, and low yield limit their large-scale applications. Carbon-based materials including graphene, carbon black, and carbon nanotubes have promising applications owing to their broadband light absorption, high stability, and low cost, [9] which are the most important prerequisites to ensure high solar energy conversion and practical application in water purification.Rational structural design for solar energy-driven water steam generation devices is significant to achieve high water evaporation efficiency and potential large-scale application. In the concept of heat localization, [10] the light-absorbing materials are integrated into the floating and thermally insulating substrates, which can effectively reduce the heat loss to the bulk water and enhance the water evaporation efficiency. Chen and co-workers developed a floating double-layer structure composed of exfoliated graphite and porous carbon foam with a water steam generation efficiency as high as 85% under 10 kW m −2 irradiation. [10a] A variety of solar energy-driven water evaporation devices with a bilayer structure, such as carbonized mushroom/polystyrene foam, [11] reduced graphene oxide/ bacterial nanocellulose biofoam, [12] graphene aerogel/polystyrene foam, [13] and carbon nanotube-coated wood, [14] were reported for high-efficiency water steam generation. However, these designed devices require precise and complicated fabrication processes, which limit their practicability and large-scale applications.Efficient utilization of abundant solar energy for clean water generation is considered a sustainable and environment friendly approach to mitigate the global water crisis. For this purpose, this study reports a flexible fire-resistant photothermal paper by combining carbon nanotubes (CNTs) and fire-resistant inorganic paper based on ultralong hydroxyapatite nanowires (HNs) for efficient solar energy-driven water steam generation and water purification. Benefiting from the structural characteristics of the HN/CNT photothermal paper, the black CNT surface layer exhibits a high light absorbability and photothermal conversion capability, the HN-based inorganic paper acts as a thermal insulator wit...

Wallpaper with multiple functions, such as fire resistance and an automatic alarm in fire disasters, will be attractive for the interior decoration of houses. Herein, we report a smart fire alarm wallpaper prepared using fire-resistant inorganic paper based on ultralong hydroxyapatite nanowires (HNs) and graphene oxide (GO) thermosensitive sensors. At room temperature, the GO thermosensitive sensor is in a state of electrical insulation; however, it becomes electrically conductive at high temperatures. In a fire disaster, high temperature will rapidly remove the oxygen-containing groups of GO, leading to the transformation process of GO from an electrically insulated state into an electrically conductive one. In this way, the alarm lamp and alarm buzzer connected with the GO thermosensitive sensor will send out the alerts to people immediately for taking emergency actions. After the surface modification with polydopamine of GO (PGO), the sensitivity and flame retardancy of the GO thermosensitive sensor are further improved, resulting in a low responsive temperature (126.9 °C), fast response (2 s), and sustained working time in the flame (at least 5 min). Compared with combustible commercial wallpaper, the smart fire alarm wallpaper based on HNs and GO (or PGO) is superior owing to excellent nonflammability and high-temperature resistance of HNs, which can protect the GO (or PGO) thermosensitive sensor from the flames. The smart fire alarm wallpaper can be processed into various shapes, dyed with different colors, and printed with the commercial printer and thus has promising applications in high-safety interior decoration of houses.