The development of low-cost electrocatalysts with high performance is important to provide sustainable hydrogen energy. In this work, via one-step sulfuration of MoO 4 2 − intercalated NiFe-layered double hydroxide ( abbr. NiFe-MoO ₄ -LDH), hierarchical microspheres are assembled by intersecting nanoplates (15–30 nm in thickness) which are then decorated with MoS ₂ and (NiFe)S _x nanoparticles (∼25 nm in size). The NiFe-MoO ₄ -LDH is synthesized beforehand by a one-pot hydrothermal reaction. Under sulfuration at 300 °C, 400 °C and 600 °C, the NiFe-MoO ₄ -LDH transforms into multi-metal sulfides of NiFeMoS- T ( T is applied temperature). During sulfuration, the confinement effect of LDH limits the growth of metal sulfides, causing formation of nanoparticles of MoS ₂ and (NiFe)S _x to expose more catalytic active sites. In an alkaline medium, NiFeMoS-400 depicts superior performance for hydrogen evolution reaction (HER), giving an overpotential of 210 mV at 10 mA cm ⁻² . A Tafel slope of 88 mV dec ⁻¹ indicates a mixed Volmer–Heyrovsky rate-determining step. The electrode also maintains long-term electrochemical durability during 15 h electrolysis at 25 mA cm ⁻² . The NiFe-MoO ₄ -LDH precursor owns three metal elements (Ni, Fe and Mo), which ensure the formation of polymetallic sulfides, and maximum utilization of the LDH layer and interlayer metals contributes to the optimal electrocatalytic activity. The NiFeMoS nanoassembly is a potential low-cost and high-efficiency electrocatalyst.

Mercury is the most toxic and harmful heavy metal pollutant, and it is essential to detect and remove mercury from beverages. Inducing the porphyrin molecules into the chitosan structure, a novel membrane sensor tetrakis(4-carboxyphenyl)porphyrin-grafted chitosan fiber membrane (TCPP-CS) was prepared by electrospinning method and applied to recognize Hg²⁺ contaminant selectively. Compared with other common metal ions (Pb²⁺, Cu²⁺, Fe³⁺, Cr³⁺, Mg²⁺, and Zn²⁺), the colorimetric sensor has specific color development and sensitivity to Hg²⁺ and the detection limit of the sensor reaches 1 × 10⁻⁵ mol·L⁻¹. The response time of the membrane is 5 s, and it can be specifically colored in various pH environments convenient for practical application. Hg²⁺ resulted in a visual color change of the fiber membrane from brown to yellow-green, indicating a potential interaction between the porphyrin-functionalized chitosan fiber membrane and Hg²⁺ ions, and the wavelength shift of the UV–visible spectrum can be observed. It has the advantages of simplicity, rapidity, high selectivity, and high sensitivity, providing a new method for removing and detecting heavy metals in traditional Chinese medicine and drinks.

Polyethersulfone-sulfonated polyethersulfone (PES-SPES)/NaY zeolite/nylon sandwich structure membranes were prepared and used to adsorb Cu²⁺ from water. The adsorption kinetics, adsorption isotherm, dynamic adsorption experiment, and reusability were discussed. The experimental data showed that the Langmuir isotherm model, Dubinin–Radushkevich (D-R) isotherm model, and the pseudo-first-order kinetic model can well represent the adsorption of Cu²⁺ on the membrane, indicating an ion exchange mechanism, with the maximum adsorption capacity of 111.25 mg·g⁻¹. Repeatability experiments show that the sandwich film still has good adsorption performance after five times of adsorption and desorption. The as-prepared membrane showed considerable separation performance in removing Cu²⁺ from aspirin solution, providing a feasible method to remove heavy metals from drugs.