The corrosion properties of 316L stainless steel (316L SS) alloy within molten NaCl-KCl salt were explored through a static immersion experiment carried out at 700 °C under Ar flow for 25, 50, 100, 200, and 400 h. The loss in weight of the corroded 316L SS alloy increased from 0.06 to 1.71 mg/cm², while the maximum corrosion depth increased from 1.71 to 14.09 μm. However, the corrosion rate initially increased from 27.54 μm/year to 93.45 μm/year and then decreased to 47.22 μm/year as the soaking time was increased from 25 to 400 h. The impurities in the molten salts produced corrosive Cl₂ and HCl, which corroded the 316L SS matrix. The accelerated selective Cr dissolution with small amounts of Fe and Ni resulted in intergranular corrosion as the time of corrosion was increased. The depletion depths for Ni, Cr, and Fe at 400 h were found to be 0.87 μm, 3.94 μm, and 1.47 μm, respectively. The formation of Cr and Fe oxides might potentially play a vital role. The grain boundary and outward diffusion of Mo may prevent the outward diffusion of Cr, thereby mitigating alloy corrosion. Therefore, molten chloride salt purification and the selection of stainless steel are crucial for developing future concentrated solar power technologies. The findings of this study provide guidelines for the use of 316L SS in NaCl-KCl salt at high temperatures.

As a well-known photocatalyst, TiO₂ still suffers from rapid electron–hole recombination and limited visible light absorption. To overcome these challenges, the combination of graphene and TiO₂ has been proposed. However, traditional methods such as ball milling and hydrothermal synthesis face limitations, including high energy consumption and complex procedures. Here, we develop a simple and industrially feasible method to prepare reduced graphene oxide (rGO)-coated TiO₂ nanoparticles, referred to as rGO-TiO₂ composites. The optimized rGO-TiO₂ composites exhibit an enhanced photocatalytic degradation of rhodamine B (RhB) under simulated sunlight conditions, about 99.95% for 4% rGO-TiO₂ within 80 min. The first-order reaction rate constant (k) of 4% rGO-TiO₂ (0.0867 min⁻¹) is 5.42 times higher than that of nano TiO₂ (0.0135 min⁻¹). The key reactive species involved in the degradation process are identified. Additionally, the effects of pH and NaCl concentration on the degradation efficiency of rGO-TiO₂ are also investigated. The 4% rGO-TiO₂ composite exhibits an excellent photocatalytic activity within the pH range of 3.87–11.89, and the NaCl concentration does not affect its photocatalytic efficiency. After characterization, the enhanced photocatalytic activity is ascribed to the introduction of rGO and the generation of surface oxygen vacancies (O_V) and Ti³⁺ in TiO₂ crystals.

The ion-enrichment inside carbon nanotubes (CNTs) offers the possibility of applications in water purification, ion batteries, memory devices, supercapacitors, field emission and functional hybrid nanostructures. However, the low filling capacity of CNTs in salt solutions due to end caps and blockages remains a barrier to the practical use of such applications. In this study, we fabricated ultra-short CNTs that were free from end caps and blockages using ball milling and acid pickling. We then compared their ion-enrichment capacity with that of long CNTs. The results showed that the ion-enrichment capacity of ultra-short CNTs was much higher than that of long CNTs. Furthermore, a broad range of ions could be enriched in the ultra-short CNTs including alkali-metal ions (e.g., K⁺), alkaline-earth-metal ions (e.g., Ca²⁺) and heavy-metal ions (e.g., Pb²⁺). The ultra-short CNTs were much more unobstructed than the raw long CNTs, which was due to the increased orifice number per unit mass of CNTs and the decreased difficulty in removing the blockages in the middle section inside the CNTs. Under the hydrated-cation–π interactions, the ultra-short CNTs with few end caps and blockages could highly efficiently enrich ions.

As a well-known photocatalyst, TiO₂, still suffers from rapid electron-hole recombination and limited visible light absorption. To overcome these challenges, the combination of graphene and TiO₂ has been proposed. However, traditional methods such as ball milling and hydrothermal synthesis face limitations, including high energy consumption and complex procedures. Here, we developed a simple and industrially feasible method to prepare reduced graphene oxide (rGO) coated TiO₂ nanoparticles, referred to as rGO-TiO₂ composites. The optimized rGO-TiO₂ composites exhibited enhanced photocatalytic degradation of of Rhodamine B (RhB) under simulated sunlight condition. The effects of pH and NaCl concentration on the degradation efficiency of rGO-TiO₂ were also investigated. Additionally, the key reactive species involved in the degradation process were identified. After characterization, the enhanced photocatalytic activity is ascribed to the introduction of rGO and the generation of surface oxygen vacancies (OV) and Ti³⁺ in TiO₂ crystals.