Linker-Based Bandgap Tuning in Conductive MOF Solid Solutions

Herein, the synthesis of Cu₃(HAB)_x(TATHB)_2-x (HAB: hexaaminobenzene, TATHB: triaminotrihydroxybenzene) is reported. Synthetic improvement of Cu₃(TATHB)₂ leads to a more crystalline framework with higher electrical conductivity value than previously reported. The improved crystallinity and analogous structure between TATHB and HAB enable the synthesis of Cu₃(HAB)_x(TATHB)_2-x with ligand compositions precisely controlled by precursor ratios. The electrical conductivity is tuned from 4.2 × 10⁻⁸ to 2.9 × 10⁻⁵ S cm⁻¹ by simply increasing the nitrogen content in the crystal lattice. Furthermore, computational calculation supports that the solid solution facilitates the band structure tuning. It is envisioned that the findings not only shed light on the ligand-dependent structure–property relationship but create new prospects in synthesizing multicomponent electrically conductive metal-organic frameworks (MOFs) for tailoring optoelectronic device applications.     

Design Principles to Maximize Non-Bonding States for Highly Tribopositive Behavior

The development of highly tribopositive materials is crucial for realizing high-performance triboelectric nanogenerators. In this study, a novel protocol to maximize the number of non-bonding electrons with local dipoles for designing highly tribopositive materials is introduced, and nitrogen-based dimethylol urea, diazolidinyl urea, and imidazolidinyl urea as promising tribopositive materials are suggested. The mechanism by which nitrogen-based materials provide highly tribopositive properties is investigated using calculations based on density functional theory. Highly electronegative atoms, such as nitrogen and oxygen, attract electrons from neighboring atoms, resulting in the formation of negative local dipoles in the highest occupied molecular orbital band composed of non-bonding electrons, thereby creating an electron-donating environment. The proposed design protocol is confirmed by quantitatively investigating the triboelectric properties of nitrogen-based materials, and analyzing the charge transfer characteristics of dimethylol urea based on dipole interactions.     

Rugged Forest Morphology of Magnetoplasmonic Nanorods that Collect Maximum Light for Photoelectrochemical Water Splitting

A feasible nanoscale framework of heterogeneous plasmonic materials and proper surface engineering can enhance photoelectrochemical (PEC) water-splitting performance owing to increased light absorbance, efficient bulk carrier transport, and interfacial charge transfer. This article introduces a new magnetoplasmonic (MagPlas) Ni-doped Au@Fe_xO_y nanorods (NRs) based material as a novel photoanode for PEC water-splitting. A two stage procedure produces core–shell Ni/Au@Fe_xO_y MagPlas NRs. The first-step is a one-pot solvothermal synthesis of Au@Fe_xO_y. The hollow Fe_xO_y nanotubes (NTs) are a hybrid of Fe₂O₃ and Fe₃O₄, and the second-step is a sequential hydrothermal treatment for Ni doping. Then, a transverse magnetic field-induced assembly is adopted to decorate Ni/Au@Fe_xO_y on FTO glass to be an artificially roughened morphologic surface called a rugged forest, allowing more light absorption and active electrochemical sites. Then, to characterize its optical and surface properties, COMSOL Multiphysics simulations are carried out. The core–shell Ni/Au@Fe_xO_y MagPlas NRs increase photoanode interface charge transfer to 2.73 mAcm⁻² at 1.23 V RHE. This improvement is made possible by the rugged morphology of the NRs, which provide more active sites and oxygen vacancies as the hole transfer medium. The recent finding may provide light on plasmonic photocatalytic hybrids and surface morphology for effective PEC photoanodes.