The low denitration activity and stability of MnO_x/TiO₂ catalyst are still challenging. In this work, a MnO_x/TiO₂ catalyst was modified via a polarization effect with tourmaline. Tourmaline with a proper fineness can improve the denitration performance of the catalytic material, obtaining the greater denitration rate above 90% in a wide temperature range and the prolonged high-efficiency denitration time. Based on the results of in-situ Fourier transform infrared spectroscopy, the reaction mechanism of the catalysts before and after modification with tourmaline follows the Langmuir-Hinshelwood mechanism, and tourmaline polarization can accelerate the adsorption rate of reaction gas and generate intermediate products liable for subsequent reaction, thus improving the denitration performance.

Twinned Mn_0.5Cd_0.5S (T-MCS) solid solution was prepared by a hydrothermal method, and then Zn_0.76Co_0.24S/T-MCS heterojunction was fabricated by an in-situ hydrothermal method. The results show that Mn_0.5Cd_0.5S solid solutions is a twinned homojunction consisting of wurtzite Mn_0.5Cd_0.5S (WZ-MCS) and zinc-blende Mn_0.5Cd_0.5S (ZB-MCS) alternately. The introduction of Zn_0.76Co_0.24S can enhance the light harvesting ability of the system and increase the number of the surface charge carriers, the H₂ production rate of 3% Zn_0.76Co_0.24S/T-MCS reaches 132.9 mmol·g^-1·h^-1 in Na₂S/Na₂SO₃ mixture solution (300 W Xe lamp, λ > 420 nm), which is 332.2 and 1.9 times greater than those of Zn_0.76Co_0.24S and T-MCS, respectively. According to the results by energy band structure analysis, the type-Ⅱ twinned homojunction between WZ-MCS and ZB-MCS can improve the bulk phase charge separation, the S-scheme heterojunction between T-MCS and Zn_0.76Co_0.24S can accelerate the interfacial charge transfer, and the REDOX capacity of the holes in T-MCS valence band and electrons in Zn_0.76Co_0.24S conduction band is retained, therefore resulting in a faster H₂ production.

To eradicate antibiotics from aqueous solution, cerium(Ce) doped ZnFe₂O₄ microspheres with different Ce mass ratios were prepared by a hydrothermal method and applied for the photocatalytic decomposition of tetracycline antibiotic. The results reveal that the introduction of Ce improves the charge separation for the photogenerated electron-hole pairs, which can be confirmed form the photocurrent spectra. The optimized sample ZnFe_1.96Ce_0.04O₄ shows a decomposition rate of 56.6% under simulated solar light within 40 min. The trapping experiments show that hydroxyl radical and superoxide radical are the main degrading species, directly involving in the decomposition of antibiotics. Moreover, the rate of hydrogen produced from water splitting photocatalyzed by ZnFe_1.96Ce_0.04O₄ reaches 230.4 μmol/(g·h) under simulated solar light irradiation.

The design and synthesis of organic polymers for photocatalytic hydrogen evolution have attracted recent attention. However, the corresponding work on the synthesis methods and optimal synthesis sites of organic polymers are not complete. This paper was to synthesize five organic polymer photocatalysts via a Suzuki cross-coupling polymerization reaction. The effect of linking position content on the photocatalytic H₂-evolution and photoelectrochemical performances of organic polymer semiconductors was investigated. The results show that the increase of 1,6-linkage pattern severely affects the photocatalytic hydrogen evolution effect. A 1,6-linked pyrene benzothiadiazole polymer (L16-PyBT) has a photocatalytic hydrogen evolution rate of 6.81 mmol/(h·g) under visible-light irradiation, which is greater than that of L2 (i.e., 2.80 mmol/(h·g) and L27-PyBT (i.e., 0.34 mmol/(h·g). The increased photocatalysis is since 1,6-linkage has a stronger π-π stacking, and better absorption/wettability. The evolution of this connection mode provides an important idea for the synthesis and design of organic polymers in the future.

The construction of step scheme (S-scheme) heterojunction with a great redox ability and a high charge transfer efficiency is an effective strategy to enhance the photocatalytic activity. ZnIn₂S₄ nanosheets were grown in-situ on the surface of perylenimide (PDI) rods via a solvothermal method. A PDI/ZnIn₂S₄ heterojunction exhibits an excellent photocatalytic performance due to its tight interfacial contact and matched band structures. Moreover, the 5% PDI/ZnIn₂S₄ affords high H₂/benzaldehyde production rates of 21.66 mmol/(g·h) and 1.02 mmol/(g·h), respectively, which is 2.12 and 3.00 folds of pristine ZnIn₂S₄, respectively when coupling the photocatalytic H₂ evolution and the benzyl alcohol oxidation in the reaction system. Based on the results by X-ray photoelectron spectroscopy, transient photoluminescence spectroscopy and electron paramagnetic resonance analysis, the formation of the built-in electric field at the interface of PDI/ZnIn₂S₄ and the S-scheme electron transfer path was confirmed. The enhanced photocatalytic performance and stability can be attributed to the close contact and rich active sites of PDI/ZnIn₂S₄, and the charge carrier migration and increased photoredox properties were improved by a S-scheme charge-transfer route. This organic-inorganic PDI/ZnIn₂S₄ S-scheme heterojunction photocatalyst can be used as a novel bifunctional photocatalyst in converting solar light into clean fuel and chemicals.

Bismuth oxide (Bi₂O₃) is an important visible-light-driven photocatalyst, which possesses an application potential in photocatalytic degradation of organic pollutants and treatment of wastewater. However, low specific surface area and rapid recombination of carriers lead to a poor photocatalytic performance of Bi₂O₃, seriously restricting its application. Besides, the particle morphology of Bi₂O₃ is also not conducive to recycling and application. In this work, a flexible Bi₂O₃/carbon paper composite photocatalyst was prepared via electrochemical deposition and subsequent in-situ oxidation to improve its photocatalytic performance and operation convenience. In the as-prepared composite photocatalysts, fern-like β-Bi₂O₃ with a hierarchical structure is grown on the carbon paper substrate. In the visible-light-driven photocatalytic degradation of phenol in water, the photocatalytic performance of Bi₂O₃/carbon paper composite can surpasses α-Bi₂O₃ powder without a hierarchical structure and precedes the β-Bi₂O₃ with a hierarchical structure. Based on the analysis of N₂ adsorption, diffuse reflection spectra, photoluminescence and reactive radical, the improved activity of Bi₂O₃/carbon paper composite is ascribed to the fern-like hierarchical structure of Bi₂O₃ and the electron capturing role of conductive carbon paper. The hierarchical structure favors the light absorption of Bi₂O₃ and its contact with reactants, while the electron capturing role of carbon paper can effectively separate the photogenerated electrons and holes in Bi₂O₃, thus promoting the utilization of carriers. In addition, the macro-size, flexibility and two-dimensional morphology of the composite also make the operation and recycling more convenient. This study provides an effective strategy for the design of flexible photocatalysts with a hierarchical structure.

In this work, the palygorskite-based aerogel was used as the carrier of essential oil to prepare high-loading fragrances and achieve long-term controlled release of essential oil. Palygorskite/wood fiber composite aerogels with a high specific surface area, a high porosity and a superior machinability were prepared with palygorskite as a three-dimensional network skeleton and wood fiber as a toughening/reinforcing material. The loading efficiency of sweet orange essential oil on the aerogels is 96% and the volatile residual oil rate is <5%. The hydrophobic modification can increase the loading efficiency of aerogels on essential oil, thus prolonging the release time of essential oil. The volatilization rate of essential oil follows a three-stage change law of short-term rapid decline, stable rate and slow decline, showing a good speed control ability of composite aerogels on the volatilization of essential oil. The fragrance agent can maintain a constant release rate of 80 mg/h for 27 h at 60 ℃, and the cumulative release time is 31 h when the aerogels volume is 4 cm³. The controlled release rate of essential oil increases with the increase of aerogels volume. The release behavior of essential oil in aerogels follows the Korsmyer-Peppa model, which belongs to the Non-Fickian diffusion.

Photocatalysis is one of the effective approaches to solve the energy and environmental problems. In the process of photocatalytic reaction, the catalysts structures, surfaces, and interfaces as well as the defects are the key factors affecting their catalytic efficiency, which can be precisely adjusted by optimizing the synthesis method and enhancing the specific performance. Different from the conventional heat transfer type heating modes, microwave-assisted synthesis is an improved strategy for synthesizing micro- and nano-materials based on the heating mechanisms such as dipole polarization, ionic conduction, conduction loss, and hysteresis loss.This method has some advantages like fast heating, uniform thermal effect and good reproducibility in the thermal synthesis of photocatalytic materials. The pointed heating and directional assembly can be induced by the specific thermal effect under microwave irradiation. Microwave-assisted synthesis has attracted wide attention. This review mainly summarized recent research progress on the microwave photocatalysts synthesis, focusing on the superhot interaction between microwave and condensed matter in the synthesis process. It is indicated that the photocatalytic performance can be enhanced through the optimization of structures, surfaces, and interfaces as well as defects of photocatalysts synthesized in microwave-assisted synthesis method.

Two-dimensional TiO₂ nanosheets at large size are of importance in the electronic devices, but the synthesis is challenging. A few-layered titanate was prepared via high-temperature solid-state reaction with Cs₂CO₃ and anatase TiO₂ as precursors. The results show that the crystallinity of cesium titanate (Cs_0.7Ti_1.825O₄) as a solid reaction product is related to the several pretreatment parameters, i.e., mixing method for precursors, molar ratio of Cs/Ti, feeding amount, and calcination duration. A single phase of Cs_0.7Ti_1.825O₄ can be obtained by calcinating the precursor mixture. However, a mixed phase of rutile TiO₂ and Cs_0.7Ti_1.825O₄ is obtained when the precursors are mixed in solution. A product Cs_0.7Ti_1.825O₄ can be obtained at 800 ℃ in a molar ratio range of n(Cs)/n(Ti) of 1/(2.6-4.0). The crystallinity of cesium titanate improves with the increase of feeding amount of total precursors or calcination duration. After calcination, cesium titanate is treated using hydrochloric acid and the protonated product of H_0.7Ti_1.825O₄ is obtained. Also, few-layered titania nanosheets (Ti_0.91O₂) are obtained via exfoliation of the protonated product with amine-based macromolecules (TBAOH). The well-ordered lamellar structure of Ti_0.91O₂ is formed when the molar ratio between TBAOH ions to the exchangeable protons in the titanate is 0.5 (n(TBAOH)/n(H⁺)=0.5). Such a layered structure is annealed and used as a photocatalyst for hydrogen evolution in water under simulated solar light with ethanol as a sacrificial agent. The photocatalytic activity of the final product is related to the ratio of TBAOH/H⁺ during exfoliation, and it is indicated that the product obtained at TBAOH/H⁺ of 0.5 exhibits the optimum hydrogen evolution activity.