Effect of Molecular Substitution and Isomerization on Charge-Transport Parameters in Molecular Organic Semiconductors

The carrier dynamics for self-assembled black phosphorus and perovskite nanocrystals enable photocatalytic conversion

Few-layer black phosphorus (BP) becomes an ideal self-assembled material with perovskite nanocrystals (NCs) for photoluminescence (PL) and photocatalysis, due to the feasible control of photogenerated charge carriers. Until now, it is still a challenge to figure out the intrinsic carrier dynamics for multifunctional photodegradation in water. In this work, a series of few-layer BP components were successfully incorporated into CsPbBr3 NCs to achieve apparent PL quenching and ˙O2--dominated photocatalytic degradation of rhodamine B in aqueous solution. The strategy of BP modification can extend photoabsorption ensuring optimized photocatalytic activity by facilitating electron transfer from CsPbBr3 to BP with strong van der Waals interactions. In particular, CsPbBr3:5%BP NC eliminates the effect of sub-bandgap luminescence centers, resulting in a low charge transfer resistance, good carrier mobility, and high photocurrent densities under light irradiation.

Unlocking Enhanced Catalysis Stability in Acidic Oxygen Evolution: Structural Insights for PEM Applications under High-Current Density

In proton exchange membrane water electrolysis (PEMWE), catalysts for acidic oxygen evolution reaction (OER) that demonstrate high current density and stability are essential. Herein, we synthesized La-doped RuO2 (La-RuO2@TM) nanorod composite catalysts in situ on titanium mesh (TM) using a one-step low-temperature pyrolysis method. La-RuO2@TM displays excellent catalytic performance (1.533 V at 100 mA cm-2) and remarkable stability, showing no significant degradation in performance over 450 hours of operation. Density functional theory (DFT) calculations indicate that the formation of the La-O-Ru local structure modulates the adsorption strength of reaction intermediates, alleviates metal (Ru) leaching, and reduces oxygen loss, significantly enhancing the material's durability in acidic OER. The PEM electrolyzer utilizing La-RuO2@TM operates at 1.815 V with a current density of 1.0 A cm-2, maintaining stable performance for 120 h at 60 °C. This study offers valuable insights for designing efficient and durable acidic OER catalysts.

Many-Body Molecular Interactions in a Memristor

Electronic transitions in molecular-circuit elements hinge on complex interactions between molecules and ions, offering a multidimensional parameter space to embed, access, and optimize material functionalities for target-specific applications. This opportunity is not cultivated in molecular memristors because their low-temperature charge transport, which is a route to decipher molecular many-body interactions, is unexplored. To address this, robust, temperature-resilient molecular memristors based on a Ru complex of an azo aromatic ligand are designed, and current-voltage sweep measurements from room temperature down to 2 K with different cooling protocols are performed. By freezing out or activating different components of supramolecular dynamics, the local Coulombic interactions between the molecules and counterions that affect the electronic transport can be controlled. Operating conditions are designed where functionalities spanning bipolar, unipolar, nonvolatile, and volatile memristors with sharp as well as gradual analog transitions are captured within a single device. A mathematical design space evolves, thereof comprising 36 tuneable parameters in which all possible steady-state functional variations in a memristor characteristic can be attainable. This enables a deterministic design route to engineer neuromorphic devices with unprecedented control over the transformation characteristics governing their functional flexibility and tunability.