Temperature is a basic parameter influencing the behavior of systems in physics, chemistry and biology. From living cells to microcircuits, a wide range of cases require thermometry techniques that can be applied to reduced areas, offering sub-micrometric resolution and high accuracy. Since traditional thermometers cannot be applied in such systems, alternative tools have been specifically designed to measure temperature at the nanoscale; including scanning thermal microscopy, non-contact optical techniques or various types of luminescent nanoparticles. Each option presents interesting advantages, but also limitations that need to be considered and understood. We provide here an overview of the main currently available nanothermometry tools, discussing their pros and cons toward potential applications.

1wileyonlinelibrary.com uniform core@shell structures with highly functional inner core and porous outer shell by a simple approach.Titanium dioxide (TiO 2 ) has been a semiconductor material of signifi cant research interest due to its fascinating features, such as nontoxicity, good chemical and thermal stability, and excellent electronic, optical, and catalytic properties, [ 5,6 ] which render it a greatly promising material in photocatalysis for the removal of inorganic and organic pollutants, [ 7 ] and for hydrogen generation, [ 8 ] as well as in dye-sensitized solar cells. [ 9 ] However, TiO 2 has a bandgap of 3.0-3.2 eV, and mainly absorbs ultraviolet (UV) light, which accounts for only ≈5% of the incoming solar energy. [ 10,11 ] Therefore, photons with energy lower than the band gap energy of TiO 2 , that is, more than 90% of the solar energy, cannot be harvested for photocatalysis. Furthermore, the fast recombination of charge carriers signifi cantly reduces the catalytic activity in practical applications. To resolve these problems, much effort, including metal-ion, and nonmetal doping, [ 12 ] dye sensitization, [ 13 ] and coupling with narrower band gap semiconductors, [ 14 ] has been undertaken toward developing the next-generation of TiO 2 -based materials. These methods have been able to extend the absorption of TiO 2 -based photocatalysts into the visible region to some extent and/or enhance the charge separation. However, to date, the photocatalytic performance of these materials remains poor and in general, they also suffer from thermal instability and photocorrosion, and are not environmentally friendly. [ 15 ] Therefore, it is challenging, yet highly desirable to develop a simple method for synthesizing a photocatalyst, which can absorb solar photons over a broad wavelength range and show largely improved photocatalytic activity, as well as overcome other problems mentioned above.Au nanoparticles (NPs) show unique, size-tunable surface plasmon resonance (SPR) in the visible range, offering a new opportunity to overcome the limits of current photocatalysts. [16][17][18] -core@porous-TiO 2 -shell microspheres is reported. They exhibit high surface area, good stability, broadband absorption from ultraviolet to near infrared, and excellent photocatalytic activity, signifi cantly better than the benchmark P25 TiO 2 . The enhanced activity is attributed to synergistic effects from nanocomponents arranged into the nanostructured architecture in such a way that favors the effi cient charge/energy transfer among nanocomponents and largely reduced charge recombination. Optical and energy-transfer properties are modeled theoretically to support our interpretations of catalytic mechanisms. In addition to yielding novel materials and interesting properties, the current work provides physical insights that can contribute to the future development of plasmon-enhanced broadband catalysts.

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SERS and plasmonic heating efficiency are combined by adjusting the ratio of radiative and non-radiative properties of self-assembled anisotropic superstructures.