Abstract:Perovskite-based photocatalysts are of significant interest in the field of photocatalysis. To date, several perovskite material systems have been developed and their applications in visible light photocatalysis studied. This article provides a review of the visible light (λ > 400 nm) active perovskite-based photocatalyst systems. The materials systems are classified by the B site cations and their crystal structure, optical properties, electronic structure, and photocatalytic performance are reviewed in detail. Titanates, tantalates, niobates, vanadates, and ferrites form important photocatalysts which show promise in visible light-driven photoreactions. Along with simple perovskite (ABO3) structures, development of double/complex perovskites that are active under visible light is also reviewed. Various strategies employed for enhancing the photocatalytic performance have been discussed, emphasizing the specific advantages and challenges offered by perovskite-based photocatalysts. This review provides a broad overview of the perovskite photocatalysts, summarizing the current state of the work and offering useful insights for their future development.

Efficient hydrogen (H 2 ) production from renewable energy source is the most important requirement to produce clean fuels. Developing materials systems with high activity and good stability for solar energy conversion has become one of the most prominent and challenging research fields in the interdisciplinary scientific community. Recently, metal-free and graphite-like carbon nitiride (g-C 3 N 4 ) based on tri-s-triazine (heptazine) units has received much attention in the photocatalysis research due to its low cost, good stability and excellent optical and electronic properties.

Photon‐coupling and electron dynamics are the key processes leading to the photocatalytic activity of plasmonic metal‐semiconductor nanohybrids. To better utilize and explore these effects, a facile large‐scale synthesis route to form Ag@AgCl cubic cages with well‐defined hollow interiors is carried out using a water‐soluble sacrificial salt‐crystal‐template process. Theoretical calculations and experimental probes of the electron transfer process are used in an effort to gain insight into the underlying plasmonic properties of the Ag@AgCl materials. Efficient utilization of solar energy to create electron‐hole pairs is attributed to the significant light confinement and enhancement around the Ag/AgCl interfacial plasmon hot spots and multilight‐reflection inside the cage structure. More importantly, an ultrafast electron transfer process (≤150 fs) from Ag nanoparticles to the AgCl surface is detected, which facilitates the charge separation efficiency in this system, contributing to high photocatalytic activity and stability of Ag@AgCl photocatalyst towards organic dye degradation.

Sol-gel coatings with different roughness and surface energy were prepared on glass substrates. Methyl triethoxysilane (MTEOS), 3-Glycidyloxypropyl trimethoxysilane (GLYMO) and fluoroalkylsilane (FAS) were used to obtain a mechanically robust icephobic coating. Different amount of hydrophobic silica nano particles was added as fillers to introduce different roughness and surface energy to the coatings. The microstructure, roughness, and surface energy, together with elemental information and surface chemical state, were investigated at room temperature. The contact angle and sliding angle were measured at different temperatures to correlate the wetting behavior at low temperature with the anti-icing performance. The ice adhesion shear strength was measured inside an ice chamber using a self-designed tester. The factors influencing the ice adhesion were discussed, and the optimum anti-icing performance found in the series of coatings. It was found that lower surface energy leads to lower ice adhesion regardless of the roughness, while the roughness plays a more complicated role. The wetting behavior of the droplet on surface changes as temperature decreases. The anti-icing performance is closely related to the antiwetting property of the surfaces at subzero temperatures.

Three-dimensional TiO 2 microspheres with different hierarchical nanostructures were synthesized by the synergistic strategies of ultrafast electrochemical spark discharge spallation process followed by thermal treatment. The morphology, crystal structure, surface area, and photocatalytic activity of the hierarchical nanostructures were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, surface area analysis, and UV−vis spectroscopy respectively. The nanostructure of hierarchical microspheres undergoes three evolution steps, which includes the change from nanosheets into hybrid nanoflakes/ nanoparticles and finally to nanoparticles as calcination temperature increases, in line with the predicable trend of increase in crystallinity and decrease in specific surface area. Compared to other forms of calcined TiO 2 samples (nanosheets and nanoparticles), the hybrid TiO 2 nanoflake/ nanoparticle hierarchical porous structure exhibits a higher photocatalytic activity for the degradation of organic compounds (methyl orange and bisphenol A). This is attributed to their larger specific surface area (∼116 m 2 /g), more abundant porosity, and good crystallinity. On the basis of this hybrid structure, a visible light sensitive Ag/TiO 2 microsphere photocatalyst is designed which shows faster degradation rate under the visible light illumination (>420 nm). The porous microspheric photocatalyst does not lose its activities after recycled use, showing great potential for practical application in environmental cleanup.