With the development of nuclear energy, the long-lived radionuclides are inevitably released into the natural environment during the mine process, fuel manufacture, nuclear power usable and spent fuel management, which are dangerous to human health and environmental pollution. Thereby the efficient elimination of radionuclides is an important parameter which affects the development of nuclear power. In recent years, the metal-organic frameworks (MOFs) have attracted worldwide attention in the adsorption of radionuclides from large volume of aqueous solutions, because of their high chemical stability, abundant functional groups and changeable porous structures. In this review, we mainly summarized the recent works of MOFs in the efficient removal of radionuclides, and to understand the interaction mechanism from batch adsorption experiments, model analysis, advanced spectroscopy analysis, and theoretical calculation. The adsorption capacities of MOFs with other materials were also summarized, and the future research opportunities and challenges are given in the perspective.

Zeolite has an excellent ion-exchange property, rich acid sites and good structure and catalysis stability. Therefore, it has been widely used in many fields, i.e., industrial catalysis, separation and adsorption, etc. However, the application of zeolite is greatly limited in many catalytic reactions involved in the large molecules due to its smaller micropore size (< 1.5 nm). The introduction of hierarchically porous structure into conventional zeolite crystals not only keeps their crystalline framework, acidic active sites and high thermal and hydrothermal stability, but also accelerates the diffusion/transfer of larger molecules and greatly decreases the formation of carbon residue, thus prolonging the catalyst life, which enables them more popular applications in the catalytic field. Herein, the recent research progresses of the control of pore structural, the synthesis strategy and mechanism of some typical kinds of hierarchically porous zeolites, including disordered mesoporous/macroporous structure, ordered mesoporous/macroporous structure, dual mesopore structure with certain orientation, hollow structure and macroporous-mesoporous-microporous structure, etc, are concluded. In addition, the application progresses of these hierarchically porous zeolites in catalytic fields are summarized. Compared with the conventional zeolites and amorphous mesopore materials, the novel hierarchically porous zeolites show more excellent catalytic performance due to the crystalline framework and the introduce of hierarchically pore structure. Finally, an outlook for the hierarchically porous zeolite promising development in the future is put forward.

MoS₂ quantum dots (QDs) decorated NH₂-MIL-125 (MoS₂ QDs/NH₂-MIL-125) heterostructures were successfully fabricated by a facile method. XRD results exhibit that NH₂-MIL-125 and MoS₂ form crystals in the synthesis process of MoS₂ QDs/NH₂-MIL-125 heterojunctions. TEM results demonstrated clearly that the MoS₂ Quantum dots with size of about 4 nm successfully disperse on the surface of NH₂-MIL-125 plate. Compared with bulk MoS₂ and NH₂-MIL-125, the MoS₂ QDs/NH₂-MIL-125 heterostructures exhibit enhanced photocatalytic performance in degradation of methyl orange under visible light irradiation, about 5.8 and 7.4 times higher that of pure bulk MoS₂ and NH₂-MIL-125, respectively. Meanwhile, MoS₂ QDs/NH₂-MIL-125 composites exhibit good stability and reusability during cycle experiment. The excellent photocatalytic activity of MoS₂ QDs/NH₂-MIL-125 heterostructures is attributed to the formation of heterojunctions between MoS₂ QDs and NH₂-MIL-125, Tacilitating separation of the photogenerated charge carries. PL results prove that MoS₂ QDs/NH₂-MIL-125 composites own lower recombination of photogenerated electrons and holes, resulting in superior photocatalytic ability.

Pt/hierarchical ZSM-5 zeolites were successfully synthesized by the steam-assisted crystallization and subsequent wetness impregnation method. Structural features were characterized by XRD, N₂ isotherm, SEM, and TEM. Its catalytic behaviors for o-xylene storage at room temperature, and catalytic combustion of stored o-xylene at elevated temperatures were evaluated. It was found that crystallinity of the product underwent a reducing tendency after introduction of mesostructure, but the mesoporosity and pore volume were remarkably increased. Compared with Pt/conventional ZSM-5 zeolite, the o-xylene adsorption capacity of Pt/hierarchical HZSM-5 was around 8 times as that of the counterpart without mesostructure. Moreover, the Pt dispersion was improved due to mesoporosity. The highly dispersed Pt nanoparticles were beneficial for catalytic combustion of o-xylene. Futhermore, Pt/hierarchical ZSM-5 showed the efficient bi-functional performance during adsorption/catalytic combustion cycling process for o-xylene. Carbon balance was kept for three cycles without secondary pollutants, showing higher adsorption capacity and better reusing stability.

The pollution of nitrogen oxides has become a serious environmental problem. Selective catalytic reduction (SCR) with zeolites is one of the most effective ways to remove nitrogen oxides. To reduce the cost of the catalysts’ preparation, a facile fabrication method of high-performance Cu-SAPO-34 catalysts without removal of templating agents was proposed. Zeolite slurry containing templating agents was directly applied as a raw material to prepare the Cu-SAPO-34 catalyst followed by pretreatment, ion exchange and one-time calcination. As prepared catalysts were systematically investigated by XRD, BET, TG, ICP, XPS, SEM, TPR, TPD, and NH₃-SCR. In the ion exchange process, different pH conditions were studied and optimized. The optimized catalyst with Cu content of 2.43% performed a cubic crystal, high acidity and catalytic activity. The NO conversion rate was more than 80% in the range of 200~450℃, and the highest value was 97.8% obtained at 300℃. Compared with the catalyst prepared from commercial SAPO-34, the as-prepared Cu-SAPO-34 catalysts without removal of templating agents exhibited similar microstructure and catalytic performance. These results indicate that the presence of a small amount of templating agent in the SAPO-34 zeolites makes no difference to fabricate high-performance Cu-SAPO-34 catalysts. It is a feasible method to prepare high-performance Cu-SAPO-34 catalysts without removal of templating agents.

Membrane fouling is still the major problem for the application of membrane separation. In this study, different amounts of silver doped mesoporous graphitic carbon nitride (m-g-C₃N₄/Ag) were introduced into casting solution by blending. The polyethersulfone (PES) nanocomposite membrane was prepared via the phase-inversion method. The impacts of m-g-C₃N₄/Ag addition on the morphology, filtration, antibacterial, photocatalytic, and antifouling properties of nanocomposite membrane were systematically studied. The results showed that the addition of m-g-C₃N₄/Ag can improve the cross-section structure of the nanocomposite membrane as well as its surface hydrophilicity. Compared with pure PES membrane, the pure water flux of the modified nanocomposite membrane increased significantly with the increase of doping amount. The protein rejection rates of all samples were over 90%, indicating that the addition of m-g-C₃N₄/Ag can significantly improve the filtration performance of the nanocomposite membrane without sacrificing the rejection performance. The anti-bacterial activity of the nanocomposite membranes was improved with the increase of m-g-C₃N₄/Ag content in which the anti-bacterial activity to P. aeruginosa was much more significant than that to E. coli. The pure PES membrane almost had not photodegradation under light irradiation. By contrast, all nanocomposite membranes exhibited good photocatalytic properties under visible light irradiation, and the photocatalytic activity improved with increase of m-g-C₃N₄/Ag. The nanocomposite membrane in which the m-g-C₃N₄/Ag content was the highest that showed the optimal photocatalysis, and the decolorization rate of methyl orange reached 63% in 120 min. The comprehensive antifouling performances of all membranes were characterized by four-step filtration experiments. It can be seen that the flux recovery ratio (FRR) of all nanocomposite membranes is much higher than that of PES membrane. The FRR of all membranes was further increased after washing with water and irradiating with visible light. In summary, the addition of m-g-C₃N₄/Ag can endow the PES membrane with the antibacterial and the photocatalytic properties under visible light irradiation, thereby improving its comprehensive antifouling performance.

TiO₂ nanofibers with a diameter size of 8-10 nm were prepared on the surface of the mesoporous SiO₂ spheres through a vapor-phase growth method. And nitrogen doped TiO₂ (N-TiO₂) nanofibers were also successfully fabricated in the same way. The N atoms replaced the oxygen sites in the lattices of TiO₂. The N-TiO₂ nanofibers exhibited a highly catalytic activity under visible irradiation. XPS, UPS, XRD, SEM, TEM, UV-Vis, and PL were used to analyze and characterize the nanofibers. The annealed nanofibers were composed of highly crystalline anatase phase. Nitrogen doping narrowed band gap of the TiO₂ nanofibers and enhanced absorption of the visible light. Meanwhile, photo-generated electrons over the N-TiO₂ nanofibers exhibited more reductive potential than those over the TiO₂ nanofibers. Thus, methanol yield was remarkably improved in CO₂ photocatalytic reduction. Upon irradiation of 300 W Xe lamp for 2 h, methanol yield was 493.4 μmol∙g^-1∙h^-1 over the N-doped TiO₂ nanofibers, and the corresponding turnover frequency (TOF) was 0.089 h^-1. Comparatively, methanol yield reached 695.1 μmol∙g^-1∙h^-1 for N-TiO₂ with a TOF of 0.125 h^-1, which enhanced by 40.1% and 40.4%, respectioely.

Improving catalysis efficiency and reducing production cost attract extensive interest for the study of photocatalyst. Herein a blue titania crystal with aluminum atoms modified on the surface was prepared by aluminum reduction and deposition. The blue titania displays a unique core-shell structure with crystallization nuclei inside and with oxygen vacancies and aluminum atoms outside. And the blue titania shows excellent photocatalytic and electrochemical performance under simulated sunlight. Under high vacuum, with vapored aluminum atoms being deposited on titania nanocrystals, Ti⁴⁺ is reduced to Ti³⁺, which creates a large number of oxygen vacancies on the surface. Additionally, moderate amounts of aluminum atoms coated on titania become photo-induced charge carrier traps, facilitating the separation and transport of charge carriers, which enhances the photocatalytic capability. TiO₂-Al_0.36 exhibits the best photocatalytic performance, degrading methyl orange in 8 min, and it shows excellent photochemical property with the photocurrent of 1.47 mA·cm^-2, which is more than 8 times as high as that of pristine titania (0.17 mA·cm^-2).