Due to surface effects and quantum size effects, nanomaterials have properties that are vastly different from those of bulk materials due to surface effects. The particle size distribution plays an important role in chemical and physical properties. The measurement and control of this parameter are crucial for nanomaterial synthesis. Dynamic light scattering (DLS) is a fast and non-invasive tool used to measure particle size, size distribution and stability in solutions or suspensions during nanomaterial preparation. In this review, we focus on the in situ sizing of nanomaterial preparation in the form of colloids, especially for metal oxide nanoparticles (MONs). The measuring principle, including an overview of sizing techniques, advantages and limitations and theories of DLS were first discussed. The instrument design was then investigated. Ex-situ and in situ configuration of DLS, sample preparations, measurement conditions and reaction cell design for in situ configuration were studied. The MONs preparation monitored by DLS was presented, taking into consideration both ex situ and in situ configuration.

The spatial distribution of heavy metals, representative detection methods of heavy metals and related research trends are summarized.

Dielectric barrier discharge plasma is one of the most popular methods to generate nanthermal plasma, which is made up of a host of high-energy electrons, free radicals, chemically active ions and excited species, so it has the property of being prone to chemical reactions. Due to these unique advantages, the plasma technology has been widely used in the catalytic fields. Compared with the conventional method, the heterogeneous catalyst prepared by plasma technology has good dispersion and smaller particle size, and its catalytic activity, selectivity and stability are significantly improved. In addition, the interaction between plasma and catalyst can achieve synergistic effects, so the catalytic effect is further improved. The review mainly introduces the characteristics of dielectric barrier discharge plasma, development trend and its recent advances in catalysis; then, we sum up the advantages of using plasma technology to prepare catalysts. At the same time, the synergistic effect of plasma technology combined with catalyst on methanation, CH₄ reforming, NO_x decomposition, H₂O₂ synthesis, Fischer–Tropsch synthesis, volatile organic compounds removal, catalytic sterilization, wastewater treatment and degradation of pesticide residues are discussed. Finally, the properties of plasma in catalytic reaction are summarized, and the application prospect of plasma in the future catalytic field is prospected.

Re@MoS₂ possesses the best NRR catalytic activity with a limiting potential of −0.43 V among TM@MoS₂ systems.

In this paper, dielectric columns with different dielectric constants are employed as dielectric materials in the packed bed reactor to investigate the dynamic behaviors of plasma interaction processes. The effects of the dielectric constants (zirconia: ε = 25 and PTFE: ε = 2.5) on the production of reactive species are studied for plasma catalysis applications. Comparison studies of discharge images, electrical characteristics, discharge dynamic evolution and spatial-temporal resolved optical emission spectroscopy are carried on when zirconia and PTFE columns are employed. The results show that there are four discharge processes existing in the packed bed reactor: surface streamer on the dielectric column, local discharge at the contact point, surface discharge on the grounded dielectric plate, and the volume discharge. The production of reactive species such as N ₂ (C ³ П _u ), N ₂ ⁺ (B ² Σ _u ⁺ ) and O(3p ⁵ P) depend on the discharge processes to a great extent. The production of the N ₂ ⁺ (B ² Σ _u ⁺ ) always accompanies the formation of the streamer by electrons direct impact process to excite the ground state nitrogen molecules to N ₂ ⁺ (B ² Σ _u ⁺ ). The O(3p ⁵ P) is generated in two different ways, which plays a major role during the voltage pulse raising and falling time, respectively. The first way is the direct and fast one-step ionization and excitation by high energy electrons with O ₂ . The second way is the energy transfer from the nitrogen metastable N ₂ (A ³ Σ _u ⁺ ) and energetic electrons, in which the O is first ionized from O ₂ and then excited to O(3p ⁵ P). Furthermore, compared with a zirconia column, a PTFE column is more conductive to the generation of reactive species.