A New “Turn-on” Naphthalenedimide-Based Chemosensor for Mercury Ions with High Selectivity: Successful Utilization of the Mechanism of Twisted Intramolecular Charge Transfer, Near-IR Fluorescence, and Cell Images

For the first time, a new near-IR “turn-on” fluorescent chemosensor with high selectivity for Hg²⁺ ions was designed according to the twisted intramolecular charge transfer (TICT) mechanism. The selective fluorescence enhancement effect can be optimized by modulating the solvent systems. And this naphthalenedimide-based sensor with long wavelength absorption and emission can be used to image intracellular Hg²⁺ ions in living Hela cells

Rapid Screening of Photoanode Materials Using Scanning Photoelectrochemical Microscopy Technique and Formation of Z‑Scheme Solar Water Splitting System by Coupling p- and n‑type Heterojunction Photoelectrodes

A scanning photoelectrochemical microscopy (SPECM) technique is applied to rapidly screening the photoelectrochemical (PEC) activities of cobalt (Co)-incorporated bismuth vanadate (BiVO₄) photocatalyst arrays with varying Co concentrations on conducting FTO and Ti substrates. The SPECM screening study is successfully utilized to determine an optimal Co concentration of 6% to improve the photocatalytic performance of BiVO₄. Subsequently, pristine and Co-doped BiVO₄ thin film photoanodes are fabricated by spin-coating/drop-casting methods with optimal precursor concentrations of Co, Bi, and V to validate the results of SPECM. Structural characterization by X-ray diffraction shows that 6% Co-BiVO₄ contains a photocatalytically active scheelite-monoclinic phase of BiVO₄. Scanning electron microscopy images and EDAX show that 6% Co is partly incorporated into the BiVO₄ lattice and the remaining accumulates on the surface in the form of cobalt oxide, which is further evidenced by X-ray photoelectron spectroscopy (XPS) and Raman studies. Co-doped BiVO₄ thin film photoanode prepared by spin-coating method exhibits similar remarkable PEC response with ∼150% increase in photocurrent density at 1.0 V vs RHE with respect to the pristine BiVO₄ photoanode. Additionally, such photoanode exhibits a cathodic shift of ∼200 mV in the onset of water oxidation photocurrent. The Mott–Schottky analysis confirms an increase in charge carrier density of Co-doped BiVO₄ photoanode. Thus, the enhanced water splitting performance by Co is attributed to largely due to (1) enhancement in water oxidation kinetics via formation of cobalt oxide (Co₃O₄) on the surface of BiVO₄, and partially due to (2) enrichment in electronic conductivity of BiVO₄ in the presence of Co. An unbiased Z-scheme solar water splitting system is demonstrated at the end of this work by combining an optimized Co-doped BiVO₄/WO₃ photoanode with a CuO/CuBi₂O₄ photocathode in a two-electrode configuration

Loading Cd_0.5Zn_0.5S Quantum Dots onto Onion-Like Carbon Nanoparticles to Boost Photocatalytic Hydrogen Generation

Carbon dots (C dots, size < 10 nm) have been conventionally decorated onto semiconductor matrixes for photocatalytic H₂ evolution, but the efficiency is largely limited by the low loading ratio of the C dots on the photocatalyst. Here, we propose an inverse structure of Cd_0.5Zn_0.5S quantum dots (QDs) loaded onto the onionlike carbon (OLC) matrix for noble metal-free photocatalytic H₂ evolution. Cd_0.5Zn_0.5S QDs (6.9 nm) were uniformly distributed on an OLC (30 nm) matrix with both upconverted and downconverted photoluminescence property. Such an inverse structure allows the full optimization of the QD/OLC interfaces for effective energy transfer and charge separation, both of which contribute to efficient H₂ generation. An optimized H₂ generation rate of 2018 μmol/h/g (under the irradiation of visible light) and 58.6 μmol/h/g (under the irradiation of 550–900 nm light) was achieved in the Cd_0.5Zn_0.5S/OLC composite samples. The present work shows that using the OLC matrix in such a reverse construction is a promising strategy for noble metal-free solar hydrogen production