In the search for photocatalysts that can directly utilize near-IR (NIR) light, we investigated three oxides Cu₃(OH)₄SO₄ (antlerite), Cu₄(OH)₆SO₄, and Cu₂(OH)₃Cl by photodecomposing 2,4-dichlorophenol over them under NIR irradiation and by comparing their electronic structures with that of the known NIR photocatalyst Cu₂(OH)PO₄. Both Cu₃(OH)₄SO₄ and Cu₄(OH)₆SO₄ are NIR photocatalysts, but Cu₂(OH)₃Cl is not. Thus, in addition to the presence of two different CuO_m and Cu′O_n polyhedra linked with CuOCu′ bridges, the presence of acceptor groups (e.g., SO₄, PO₄) linked to the metal oxygen polyhedra is necessary for NIR photocatalysts.

A visible-light-responsive bismuth-based metal–organic framework (Bi-mna) is demonstrated to show good photoelectric and photocatalytic properties. Combining experimental and theoretical results, a ligand-to-ligand charge transfer (LLCT) process is found to be responsible for the high performance, which gives rise to a longer lifetime of photogenerated charge carriers. Our results suggest that bismuth-based MOFs could be promising candidates for the development of efficient visible-light photocatalysts.

A series of amorphous silver silicates with different compositions were synthesized for the first time by one-step co-precipitation. Silicate ions were found to have important role on determining visible light absorption and photocatalytic activities of amorphous silver silicates, and the sample with Ag/Si ratio of 3.20 exhibits optimal photocatalytic activity.

Plasmonic photocatalysts, which have intensive light absorption and high charge-separation efficiencies, are regarded as promising candidates to solve energy and environmental issues in the future. In this Review, we summarize recent developments in the synthesis, activity, and mechanism of plasmonic photocatalysts, with the aim of stimulating improvements in photocatalytic activities and promoting the development of photocatalysis. The materials systems, energy-transfer mechanisms, and factors that influence the photocatalytic activities of plasmonic photocatalysts are discussed. Some perspectives for the future development of the design of highly efficient plasmonic photocatalysts are proposed.

A novel 3D AgCl hierarchical superstructure, with fast growth along the 〈111〉 directions of cubic seeds, is synthesized by using a wet chemical oxidation method. The morphological structures and the growth process are investigated by scanning electron microscopy and X-ray diffraction. The crystal structures are analyzed by their crystallographic orientations. The surface energy of AgCl facets {100}, {110}, and {111} with absorbance of Cl⁻ ions is studied by density functional theory calculations. Based on the experimental and computational results, a plausible mechanism is proposed to illustrate the formation of the 3D AgCl hierarchical superstructures. With more active sites, the photocatalytic activity of the 3D AgCl hierarchical superstructures is better than those of concave and cubic ones in oxygen evolution under irradiation by visible light.

We prepared BiOCl_1−xBr_x (x=0–1) solid solutions and characterized their structures, morphologies, and photocatalytic properties by X-ray diffraction, diffuse reflectance spectroscopy, scanning electron microscopy, Raman spectroscopy, photocurrent and photocatalytic activity measurements and also by density functional theory calculations for BiOCl, BiOBr, BiOCl_0.5Br_0.5. Under visible-light irradiation BiOCl_1−xBr_x exhibits a stronger photocatalytic activity than do BiOCl and BiOBr, with the activity reaching the maximum at x=0.5 and decreasing gradually as x is increased toward 1 or decreased toward 0. This trend is closely mimicked by the photogenerated current of BiOCl_1−xBr_x, indicating that the enhanced photocatalytic activity of BiOCl_1−xBr_x with respect to those of BiOCl and BiOBr originates from the trapping of photogenerated carriers. Our electronic structure calculations for BiOCl_0.5Br_0.5 with the anion (O²⁻, Cl⁻, Br⁻) and cation (Bi³⁺) vacancies suggest that the trapping of photogenerated carriers is caused most likely by Bi³⁺ cation vacancies, which generate hole states above the conduction band maximum.

Well-faceted nanocrystals of anatase TiO₂ with specific reactive facets have attracted extraordinary research interest due to their many intrinsic shape-dependent properties. In this work, hierarchical TiO₂ microspheres consisting of anatase nanosheets or decahedrons were synthesized by means of a facile hydrothermal technique; meanwhile, the percentage of {001} facets can be tuned from 82 to 45 %. Importantly, by investigating the photo-oxidation reactions for ^.OH radical generation and photoreduction reactions for hydrogen evolution, the TiO₂ microspheres consisting of nano-decahedrons with 45 % {001} facets show superior photoreactivity (more than 4.8-times) compared to the nanosheets with 82 % {001} facets. By analyzing the results of scanning electron microscopy (SEM), photoluminescence (PL) and first-principles density functional theory (DFT) calculations, a model of charge separation between the well-formed {001} and {101} facets is proposed, and the enhanced photocatalytic efficiency is largely attributed to the efficient separation of photogenerated charges among the crystal facets co-exposed.

New plasmonic photocatalysts Ag@Ag(Cl,Br) and Ag@AgCl-AgI were synthesized by the ion-exchange process between AgCl and a potassium halide (KBr, KI), then by reducing some Ag⁺ ions in the surface region of Ag(Cl,Br) and AgCl-AgI particles to Ag⁰ species. The Ag nanoparticles were formed from Ag(Cl,Br) and AgCl-AgI by a light-induced chemical reduction. The Ag@Ag(Cl,Br) and Ag@AgCl-AgI particles have irregular shapes and their sizes vary between 100 nm and 1.3 μm. The as-grown plasmonic photocatalysts show strong absorption in the visible-light region, owing to the plasmon resonance of Ag nanoparticles. The ability of this compound to oxidize methylic orange and reduce Cr^VI under visible light was compared with those of other reference photocatalysts. These plasmonic photocatalysts have been shown to be highly efficient under visible-light irradiation.

By means of a simple ion-exchange process (using different precursors) and a light-induced chemical reduction reaction, highly efficient Ag@AgCl plasmonic photocatalysts with various self-assembled structures—including microrods, irregular balls, and hollow spheres—have been fabricated. All the obtained Ag@AgCl catalysts were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and UV-visible diffuse reflectance spectroscopy. The effect of the different morphologies on the properties of the photocatalysts was studied. The average content of elemental Ag in Ag@AgCl was found to be about 3.2 mol %. All the catalysts show strong absorption in the visible-light region. The obtained Ag@AgCl samples exhibit enhanced photocatalytic activity for the degradation of organic contaminants under visible-light irradiation. The stability of the plasmonic photocatalysts was also investigated in detail.

The new plasmonic photocatalyst Ag@Ag(Br,I) was synthesized by the ion-exchange process between the silver bromide and potassium iodide, then by reducing some Ag⁺ ions in the surface region of Ag(Br,I) particles to Ag⁰ species. Ag nanoparticles are formed from Ag(Br,I) by the light-induced chemical reduction reaction. The Ag@Ag(Br,I) particles have irregular shapes with their sizes varying from 83 nm to 1 μm. The as-grown plasmonic photocatalyst shows strong absorption in the visible light region because of the plasmon resonance of Ag nanoparticles. The ability of this compound to reduce Cr^VI under visible light was compared with those of other reference photocatalyst. The plasmonic photocatalyst is shown to be highly efficient under visible light. The stability of the photocatalyst was examined by X-ray diffraction and X-ray photoelectron spectroscopy. The XRD pattern and XPS spectra prove the stability of the plasmonic photocatalyst Ag@Ag(Br,I).

Hierarchical Bi₂O₂CO₃ flowerlike microstructures have been synthesized for the first time using a facile, template-free, and low-temperature solution method. With an average diameter of about 3 μm, the as-prepared Bi₂O₂CO₃ microflowers are composed of numerous two-dimensional nanosheets with oriented terminal engagement. On the basis of electron microscopy observations, a plausible growth mechanism is proposed as a spatial self-assembly process accompanied by Ostwald ripening. The molar ratio of the initial reagents plays an important role in determining the morphologies of the Bi₂O₂CO₃ microstructures. UV/Vis spectroscopy is employed to analyze the band gaps of the products. Both mesopores and macropores are revealed in the Bi₂O₂CO₃ microflowers by means of nitrogen sorption and pore-size distribution. Moreover, evaluated by the degradation of methyl orange under UV illumination, the photocatalytic performance of the Bi₂O₂CO₃ hierarchical microflowers is almost six times higher than that of commercial Bi₂O₂CO₃. The higher specific surface area, the meso/macropores, and the intra-electric field formed between the (Bi₂O₂)²⁺ layer and the slabs comprising CO₃²⁻ in the Bi₂O₂CO₃ crystal structure, are believed to facilitate the separation of the photoinduced electrons and holes and thus improve the corresponding photocatalytic activity.