YCl3-Substituted CsPbI3 Perovskite Nanorods for Efficient Red-Light-Emitting Diodes

Cesium lead iodide (CsPbI₃) perovskite nanocrystals (NCs) are a promising material for red-light-emitting diodes (LEDs) due to their excellent color purity and high luminous efficiency. However, small-sized CsPbI₃ colloidal NCs, such as nanocubes, used in LEDs suffer from confinement effects, negatively impacting their photoluminescence quantum yield (PLQY) and overall efficiency. Here, we introduced YCl₃ into the CsPbI₃ perovskite, which formed anisotropic, one-dimensional (1D) nanorods. This was achieved by taking advantage of the difference in bond energies among iodide and chloride ions, which caused YCl₃ to promote the anisotropic growth of CsPbI₃ NCs. The addition of YCl₃ significantly improved the PLQY by passivating nonradiative recombination rates. The resulting YCl₃-substituted CsPbI₃ nanorods were applied to the emissive layer in LEDs, and we achieved an external quantum efficiency of ~3.16%, which is 1.86-fold higher than the pristine CsPbI₃ NCs (1.69%) based LED. Notably, the ratio of horizontal transition dipole moments (TDMs) in the anisotropic YCl₃:CsPbI₃ nanorods was found to be 75%, which is higher than the isotropically-oriented TDMs in CsPbI₃ nanocrystals (67%). This increased the TDM ratio and led to higher light outcoupling efficiency in nanorod-based LEDs. Overall, the results suggest that YCl₃-substituted CsPbI₃ nanorods could be promising for achieving high-performance perovskite LEDs.

Orientation-Adjustable Metal-Organic Framework Nanorods for Efficient Oxygen Evolution Reaction

A series of orientation-adjustable metal-organic framework (MOF) nanorods, CoFe(dobpdc)-I to CoFe(dobpdc)-III (dobpdc = 4,4'-dihydroxybiphenyl-3,3'-dicarboxylate), is developed on a 3D nickel foam (NF) template. By modulating the solvent composition for synthesis, the feature of MOF nanorods on the template can be varied from disorganized to a unidirectional orientation perpendicular to the NF. Well-aligned, vertically oriented CoFe(dobpdc)-III nanorods are hydrophilic and have more exposed active sites and interfacial charge transfer ability. Consequently, they exhibit a superior activity for oxygen evolution reaction (OER) with ultralow overpotentials of 176 and 240 mV at 10 and 300 mA cm^-2 in 1.0 M KOH (aq), respectively. CoFe(dobpdc)-III also shows a record low overpotential of 204 mV at J₁₀ mA cm^-2 among the electrocatalysts based on CoFe MOF and an excellent overpotential at a high current density (100 mA cm^-2) of 312 mV in 0.1 M KOH (aq). This is the first report of a convenient method to straighten up MOF nanorods on a template for highly efficient OER.

High Na+ Mobility in rGO Wrapped High Aspect Ratio 1D SbSe Nano Structure Renders Better Electrochemical Na+ Battery Performance

We chose to understand the cyclic instability and rate instability issues in the promising class of Na⁺ conversion and alloying anodes with Sb₂ Se₃ as a typical example. We employ a synthetic strategy that ensures efficient rGO (reduced graphene oxide) wrapping over Sb₂ Se₃ material. By utilization of the minimum weight of additive (5 wt.% of rGO), we achieved a commendable performance with a reversible capacity of 550 mAh g^-1 at a specific current of 100 mA g^-1 and an impressive rate performance with 100 % capacity retention after high current cycling involving a 2 Ag^-1 intermediate current step. The electrochemical galvanostatic intermittent titration technique (GITT) has been employed for the first time to draw a rationale between the enhanced performance and the increased mobility in the rGO wrapped composite (Sb₂ Se₃ -rGO) compared to bare Sb₂ Se₃ . GITT analysis reveals higher Na⁺ diffusion coefficients (approx. 30 fold higher) in the case of Sb₂ Se₃ -rGO as compared to bare Sb₂ Se₃ throughout the operating voltage window. For Sb₂ Se₃ -rGO the diffusion coefficients in the range of 8.0×10^-15  cm²  s^-1 to 2.2×10^-12  cm²  s^-1 were observed, while in case of bare Sb₂ Se₃ the diffusion coefficients in the range of 1.6×10^-15  cm²  s^-1 to 9.4×10^-15  cm²  s^-1 were observed.

Preparation of silver-loaded titanium dioxide hedgehog-like architecture composed of hundreds of nanorods and its fast response to xylene

Hedgehog-like titanium dioxide (TiO₂) architectures composed of hundreds of one-dimensional (1D) nanorods and silver (Ag) loaded TiO₂ with different amounts (0.2 at%, 0.5 at% and 1 at%) were successfully prepared by facile hydrothermal process and simple isometric impregnation route. The high electron mobility of 1D nanorods on the surface of TiO₂ and the high porosity of Ag loaded hedgehog-like TiO₂ architectures enable the sensor with fast responsive and recovered properties. TiO₂ loaded with 0.5 at% Ag exhibited the highest response to xylene with low response/recovery time at the operating temperature of 375 °C. In addition, the sensitivity and selectivity of the TiO₂ sensor were enhanced markedly with Ag loading.