Search

Near‐infrared (NIR) phosphor‐converted light–emitting diodes (pc‐LEDs) are increasingly used in night vision, surveillance, and biomedicine. A major challenge is to identify a phosphor that efficiently converts blue light into wideband NIR emission. In this paper, a rare‐earth divalent europium (Eu2+)‐activated halogen oxide (Sr3GeO4Cl2) phosphor is unlocked via a high‐temperature solid‐state reaction. The Sr3GeO4Cl2:Eu2+ phosphor emits a wide spectrum (500–950 nm) with a peak at 700 nm when excited by 450 nm blue light. Extended X‐ray absorption fine structure (EXAFS) analysis reveals that the NIR emission primarily originates from Eu2+ ions, and the Eu─O bond length closely resembles the Sr─O bond length. Lattice engineering, specifically Ge/Si cation substitution, increased Eu2+ incorporation into the crystal lattice, boosting luminescence intensity by 75%–122% and quantum efficiency from 15% to 26%. This is related to the combined effect of reduced non‐radiative energy transfer and changes in the local lattice structure of Eu2+. A NIR pc‐LED device using the optimized phosphor showed a photoelectric efficiency of 16.5% and an optical output of 25.07 mW at 100 mA. This study not only explores new Eu2+‐activated NIR phosphors but also highlights the importance of crystal engineering to enhance luminescence properties, guiding future research for efficient NIR pc‐LED development. [ABSTRACT FROM AUTHOR]

Construction of bifunctional catalysts with balanced adsorption toward multiple reactants and intermediates is crucial for efficient urea‐assisted water splitting. Nickel Sulfide (NiS) is considered as a promising choice for both urea oxidation reaction (UOR) and hydrogen evolution reaction (HER), whereas the highly occupied d orbital of Ni sites results in too weak reactant adsorption to achieve satisfactory bifunctionality. Herein, considering the adsorption‐energy scaling limitations, another Mo4+ site with empty d orbital is introduced into NiS crumpled nanoflowers as a reactant mediator for accelerated urea electrolysis. Based on the in situ characterizations and theoretical calculations, a dual‐center catalytic mechanism is proposed that the Mo4+ sites govern the reactant adsorption, subsequently cooperate with nearby Ni sites to promote the reactant dissociation, intermediate formation, and product desorption. The crumpled flower‐like nanostructure also provides abundant active sites and rapid mass transfer. Consequently, the Mo‐NiS exhibits excellent UOR/HER bifunctionality in an anion‐exchange membrane (AEM) flow electrolyzer. Compared with the pure‐water electrolysis system, the urea‐assisted water electrolyzer saves 15% energy to produce hydrogen. Besides, this electrolyzer obtains an ampere‐level current density of 1 A cm−2 at the cell voltage of 2.0 V, about 2.56 times higher than that of the assembly of RuO2||Pt/C, and robust durability. [ABSTRACT FROM AUTHOR]