An annealing-assisted preparation method of well-crystallized VxW1-xO2(M)@SiO2 core-shell nanoparticles for VO2-based thermochromic smart coatings (VTSC) is presented. The additional annealing process reduces the defect density of the initial hydrothermally prepared VxW1-xO2(M) nanoparticles and enhances their crystallinity so that the thermochromic film based on VxW1-xO2(M)@SiO2 nanoparticles can exhibit outstanding thermochromic performance with balanced solar regulation efficiency (ΔTsol) of 17.3%, luminous transmittance (Tlum) up to 52.2%, and critical phase transition temperature (Tc) around 40.4 °C, which is very promising for practical application. Furthermore, it makes great progress in reducing Tc of VTSC to near room temperature (25.2 °C) and simutaneously maintaining excellent optical properties (ΔTsol = 14.7% and Tlum = 50.6%). Such thermochromic performance is good enough to make VTSC applicable to practical architecture.

Enhancing catalytic activity by decorating noble metals in catalysts provides an opportunity for promoting the electrocatalytic hydrogen evolution reaction (HER) application. However, there are few systematic studies on regulating the structures of noble metals in catalytic materials and investigating their influence on HER. Herein, Pt catalysts with different structures including single atoms (SAs), clusters, and nanoparticles well-controllably anchored on VS2 nanosheets through a cost-effective optothermal method are reported, and their HER performance is studied. The most efficient Pt-decorated VS2 catalyst (with both Pt SAs and clusters) delivers an overpotential of 77 mV at 10 mA cm–2, close to that of Pt/C (48 mV). However, the optimal mass activity of Pt (normalizing to Pt content) is obtained from only SA Pt-decorated VS2 (i.e., 22.88 A mgPt –1 at 200 mV) and is 12 times greater than that of the Pt/C (1.87 A mgPt –1), attributed to the greatly enhanced Pt utilization. Additionally, the theoretical simulations reveal that Pt SA decoration makes the adsorption free energy of H* closer to the thermoneutral value and improves the charge-transfer kinetics, significantly enhancing HER activity. This work offers a pathway to prepare the desired catalyst based on synergy of Pt structures and VS2 and reveals the intrinsic mechanism for enhancing catalytic activity, which is important for HER applications.

Vanadium dioxide (VO), as a typical thermochromic material used in smart windows, is always limited by its weaker solar regulation efficiency (ΔT) and lower luminous transmittance (T). Except for common approaches such as doping, coating, and special structure, compositing is another effective method. The macroscopic thermochromic (from colorless to blue) ionic liquid-nickel-chlorine (IL-Ni-Cl) complexes are selected in this paper to be combined with VO nanoparticles forming a composite film. This novel scheme demonstrates outstanding optical properties: ΔT = 26.45% and T = 66.44%, T = 43.93%. Besides, the addition of the IL-Ni-Cl complexes endows the film with an obvious color change from light brown to dark green as temperature rises. This splendid visible thermochromic performance makes the composite film superior in function exhibiting and application of smart windows.

For VO-based thermochromic smart windows, high luminous transmittance (T) and solar regulation efficiency (ΔT) are usually pursued as the most critical issues, which have been discussed in numerous researches. However, environmental durability, which has rarely been considered, is also so vital for practical application because it determines lifetime and cycle times of smart windows. In this paper, we report novel VO@ZnO core-shell nanoparticles with ultrahigh durability as well as improved thermochromic performance. The VO@ZnO nanoparticles-based thermochromic film exhibits a robust durability that the ΔT keeps 77% (from 19.1% to 14.7%) after 10 hours in a hyperthermal and humid environment, while a relevant property of uncoated VO nanoparticles-based film badly deteriorates after 30 h. Meanwhile, compared with the uncoated VO-based film, the VO@ZnO-based film demonstrates an 11.0% increase (from 17.2% to 19.1%) in ΔT and a 31.1% increase (from 38.9% to 51.0%) in T. Such integrated thermochromic performance expresses good potential for practical application of VO-based smart windows.