Efficient pollutant degradation under ultraviolet to near-infrared light irradiation and dark condition using CuSe nanosheets: Mechanistic insight into degradation

The hydrothermally prepared two-dimensional copper selenide nanosheets (2D CuSe NSs) have been employed for the first time to degrade rhodamine B (RhB) in the presence of hydrogen peroxide (H₂O₂) under ultraviolet to near-infrared (NIR) light irradiation and dark condition. The experimental measurements demonstrate that 99.7% RhB is degraded under NIR light irradiation for 120 min. Moreover, the experimental tests clearly demonstrate that the 2D CuSe NSs display excellent ability to degrade RhB under dark condition. The different degradation mechanisms under the light irradiation and dark condition have been revealed by the experimental tests through the investigation of H₂O₂ role and the evaluation of hydroxyl radicals (•OH) and H₂O₂ concentration during the degradation reaction. Under light irradiation, the H₂O₂ traps the photogenerated electrons of the CuSe to generate •OH and hydroxide ion (OH^-), and the holes react with OH^- to produce •OH, making RhB to be degraded efficiently. Under dark conduction, the 2D CuSe NSs react with H₂O₂ to exhibit Fenton-like process to degrade RhB with a degradation rate of 90.0% within 120 min. This work opens a pathway for developing nanostructures with full-solar-responsive and strong near-infrared photocatalytic activity as well as Fenton-like reaction to efficiently degrade pollutants under light irradiation and dark condition.

Heat-Up Colloidal Synthesis of Shape-Controlled Cu-Se-S Nanostructures-Role of Precursor and Surfactant Reactivity and Performance in N2 Electroreduction

Copper selenide-sulfide nanostructures were synthesized using metal-organic chemical routes in the presence of Cu- and Se-precursors as well as S-containing compounds. Our goal was first to examine if the initial Cu/Se 1:1 molar proportion in the starting reagents would always lead to equiatomic composition in the final product, depending on other synthesis parameters which affect the reagents reactivity. Such reaction conditions were the types of precursors, surfactants and other reagents, as well as the synthesis temperature. The use of 'hot-injection' processes was avoided, focusing on 'non-injection' ones; that is, only heat-up protocols were employed, which have the advantage of simple operation and scalability. All reagents were mixed at room temperature followed by further heating to a selected high temperature. It was found that for samples with particles of bigger size and anisotropic shape the CuSe composition was favored, whereas particles with smaller size and spherical shape possessed a Cu2-xSe phase, especially when no sulfur was present. Apart from elemental Se, Al2Se3 was used as an efficient selenium source for the first time for the acquisition of copper selenide nanostructures. The use of dodecanethiol in the presence of trioctylphosphine and elemental Se promoted the incorporation of sulfur in the materials crystal lattice, leading to Cu-Se-S compositions. A variety of techniques were used to characterize the formed nanomaterials such as XRD, TEM, HRTEM, STEM-EDX, AFM and UV-Vis-NIR. Promising results, especially for thin anisotropic nanoplates for use as electrocatalysts in nitrogen reduction reaction (NRR), were obtained.

A hierarchically-assembled Fe–MoS2/Ni3S2/nickel foam electrocatalyst for efficient water splitting

Hierarchically-assembled Fe–MoS₂/Ni₃S₂/NF demonstrates excellent HER, OER and full water splitting catalytic performances in an alkaline electrolyte.