Mechanochromic response is of great importance in designing bionic robot systems and colorimetric devices. Unfortunately, compared to mimicking motions of natural creatures, fabricating mechanochromic systems with programmable colorimetric responses remains challenging. Herein, we report the development of unconventional mechanochromic films based on hybrid nanorods integrated with magnetic and plasmonic anisotropy. Magneticplasmonic hybrid nanorods have been synthesized through a unique space-confined seedmediated process, which represents an open platform for preparing next-generation complex nanostructures. By coupling magnetic and plasmonic anisotropy, the plasmonic excitation of the hybrid nanorods could be collectively regulated using magnetic fields. It facilitates convenient incorporation of the hybrid nanorods into polymer films with a well-controlled orientation and enables sensitive colorimetric changes in response to linear and angular motions. The combination of unique synthesis and convenient magnetic alignment provides an advanced approach for designing programmable mechanochromic devices with the desired precision, flexibility, and scalability.

Magnetic assembly at the nanoscale level holds great potential for producing smart materials with high functional and structural diversity. Generally, the chemical, physical, and mechanical properties of the resulting materials can be engineered or dynamically tuned by controlling external magnetic fields. This Review reviews the recent research progress on nanoscale magnetic assembly approaches toward the development of smart materials. The magnetic interactions between nanoparticles (both magnetic and nonmagnetic) and the interactions between nanoparticles and external magnetic fields are fully expatiated based on numerical simulations. In particular, the advancements of nanoscale magnetic assembly in responsive optical nanostructures, shape-morphing systems, and advanced materials with tunable surface properties are introduced in three subsections. The key roles of magnetic interactions in nanoscale assembly toward customizable physical and chemical properties are highlighted, with focus on how to enable direct manipulation of the positional and orientational orders of the building blocks and orientational control of soft matrices through the incorporation of anisotropic magnetic structures.

Solar-driven interfacial steam generation is a promising technique for clean water production because it can minimize thermal loss by localizing solar-to-heat conversion at the air/liquid interface. Here we report an integrated solar evaporator by partially growing 2D polypyrrole microsheets within a melamine foam through chemical vapor polymerization. These microsheets can induce multiple light reflections within the foam, enable omnidirectional light absorption, provide abundant surfaces to promote heat transfer, and achieve spatially defined hydrophobicity to facilitate vapor escape. Meanwhile, the inherent hydrophilicity of the bottom part of the foam promotes spontaneous upward water transport and suppresses heat loss. The composite foam exhibits an excellent apparent evaporation rate of ∼2 kg/(m 2 •h) and solar-to-vapor efficiency of ∼91%. The combined advantages of large surface area, high efficiency, low cost, all-weather application, excellent durability, and scalable manufacturing make our integrated design promising for fabricating large-scale solar steam generation systems that are suitable for practical clean water production.

The nonradiative conversion of light to heat by plasmonic nanostructures, the so‐called plasmonic photothermal effect, has attracted enormous attention due to their widespread potential applications. Herein, the perspectives on the design and preparation of plasmonic nanostructures for light to heat or photothermal conversion are provided. The general principle of plasmonic photothermal conversion is first introduced, and then, the strategies for improving efficiency are discussed, which is the focus of this field. Then, five typical application types are used, including solar energy harvesting, photothermal actuation, photothermal therapy, laser‐induced color printing, and high‐temperature photothermal devices, to elucidate how to tailor the nanomaterials to meet the requirements of these specific applications. In addition to the photothermal effect, other unique physical and chemical properties are coupled to further explore the application scenarios of plasmonic photothermal materials. Finally, a summary and the perspectives on the directions that may lead to the future development of this exciting field are also given.

Bottom-up nanowires are attractive for realizing semiconductor devices with extreme heterostructures because strain relaxation through the nanowire sidewalls allows the combination of highly lattice mismatched materials without creating dislocations. The resulting nanowires are used to fabricate light-emitting diodes (LEDs), lasers, solar cells, and sensors. However, expensive single crystalline substrates are commonly used as substrates for nanowire heterostructures as well as for epitaxial devices, which limits the manufacturability of nanowire devices. Here, nanowire LEDs directly grown and electrically integrated on metal are demonstrated. Optical and structural measurements reveal high-quality, vertically aligned GaN nanowires on molybdenum and titanium films. Transmission electron microscopy confirms the composition variation in the polarization-graded AlGaN nanowire LEDs. Blue to green electroluminescence is observed from InGaN quantum well active regions, while GaN active regions exhibit ultraviolet emission. These results demonstrate a pathway for large-scale fabrication of solid state lighting and optoelectronics on metal foils or sheets.