Nonmetal doping is a convenient method to adjust the visible light photocatalytic activity of graphitic carbon nitride (g-C₃N₄).

It is still a challenge to design an efficient and low-cost electrocatalyst for the hydrogen evolution reaction (HER) in an alkaline electrolyte. Herein, ultra-low amount Pt-doped Co₂P/Ni₂P on nickel foam (Pt/Co₂P/Ni₂P/NF) was facilely synthesized via an in situ controlled growth and used as an efficient electrocatalyst for electrolytic water splitting into hydrogen. Pt/Co₂P/Ni₂P/NF was achieved by a two-step procedure that was conducted by the hydrothermal approach to obtain the precursor, followed by a subsequent in situ phosphorization procedure. Due to the NF substrate being supermacroporous, more active sites of Pt/Co₂P/Ni₂P/NF could be exposed, improving electron transport and providing open-channels for the rapid release of H₂. Pt/Co₂P/Ni₂P/NF exhibited remarkable electrocatalytic performance towards HER with an overpotential of 75 mV at 10 mA cm⁻² in an alkaline electrolyte and a small Tafel slope of 64 mV dec⁻¹. This work provided a facile and reliable synthetic approach to improve transition metal phosphides (TMPs) for electrocatalytic HER performance in alkaline electrolytes.

Hydrogen production technology has triggered a research boom in order to alleviate the problems of environmental pollution and the pressure on non-renewable energy sources. The key factor of this technology is the use of an efficient photocatalyst. g-C₃N₄ is a typical semiconductor photocatalytic material that is non-toxic and environmentally friendly and does not cause any serious harm to human beings. Therefore, it can be applied to drug degradation and the photocatalytic production of H₂. Combined with ZnIn₂S₄, this semiconductor photocatalytic material, with a typical lamellar structure, has become one of the most promising catalysts for research due to its suitable bandgap structure and excellent photoelectric properties. In this study, 10% g-C₃N₄/ZnIn₂S₄ nano-heterojunction composite photocatalytic materials were successfully prepared by compounding ZnIn₂S₄ and g-C₃N₄ semiconductor materials with good visible-light-trapping ability. Under visible light irradiation, the photocatalytic activity of the composites was significantly better than that of pure g-C₃N₄ and ZnIn₂S₄. This is attributed to the formation of a heterojunction structure, which effectively inhibited the recombination of photogenerated carriers through the interfacial contact between the two semiconducting materials, and then improved the separation efficiency of the photogenerated electron–hole pairs, thus enhancing the catalytic activity. In this study, pure g-C₃N₄ and ZnIn₂S₄ were prepared using calcination and hydrothermal methods, and then, the composites were synthesized using ultrasonic and hydrothermal means. The differences in the structure, morphology, and hydrogen production performance of the materials before and after recombination were analyzed in detail using XRD, SEM, and FTIR characterization, which further verified that the 10% g-C₃N₄/ZnIn₂S₄ nano-heterojunction composites possessed excellent photocatalytic activity and stability, providing new possibilities for the optimization and application of photocatalytic hydrogen production technology.

The SnS₂/MoS₂ nanospheres (NPs) were prepared by a facile hydrothermal route, and microstructure and morphology were investigated by SEM, TEM, XRD and BET. The SnS₂/MoS₂ NPs exhibited the excellent adsorption properties for organic dyes, and the maximum adsorption capacity of SnS₂/MoS₂ to Rhodamine B (RhB) is 125 mg g⁻¹ at room temperature. The adsorption process is well fit by the pseudo-second-order adsorption model and Langmuir isotherm model. Moreover, SnS₂/MoS₂ NPs has outstanding adsorption capacity for both cations and anions organic dyes, and the maximum adsorption capacity for methylene blue (MB), crystal violet (CV) and malachite green (MG) were 202, 165 and 175 mg g⁻¹ respectively. It is attribute to the high specific surface area (101.06 m² g⁻¹) and small mesopores (3.23 nm) provide numerous adsorption active sites for adsorption of organic dyes. The reusability experiment demonstrated the SnS₂/MnS₂ NPs could be reused for 5 times. The result show that the SnS₂/MoS₂ NPs is a potential adsorbent for removal of organic dyes from wastewater.

Excess fluoride in aqueous solutions can significantly affect dental and bone health. This study used two methods to prepare hydroxyapatite to remove fluoride ions from water. The experiments showed that the adsorption capacity and removal rate of hydroxyapatite (Xq-HAP) prepared by the novel method were higher than for the hydroxyapatite (Yt-HAP) prepared by the conventional method. The maximum fluoride ion trapping capacity of Xq-HAP could reach 29.04 mg g⁻¹ under the conditions of pH = 5 and an F ion concentration of 10 mg L⁻¹. The materials were characterized by SEM, XRD, BET, XPS, and FTIR. An investigation was conducted to examine the impact of contact time, adsorbent dosage, fluoride concentration, solution pH, temperature, and several other parameters on the removal of fluoride. Adsorption equilibrium was reached in approximately 3 h at an initial fluoride concentration of 10 mg L⁻¹. It can be seen that the adsorbent has a faster ability to trap fluoride ions. The adsorption kinetics and Langmuir isotherm indicated that fluoride ion adsorption is a monolayer chemisorption process. Further characterization and kinetic studies indicated that the removal mechanism involves ion exchange, electrostatic interactions, and complexation. After five adsorption cycles, the adsorption capacity reaches 23 mg g⁻¹.

Schematic illustration of the preparation of P-doped ultrathin g-C ₃ N ₄ .