Controlled Synthesis of Terbium-Doped Colloidal Gd2O2S Nanoplatelets Enables High-Performance X-ray Scintillators.

Terbium-doped gadolinium oxysulfide (Gd2O2S:Tb3+), commonly referred to as Gadox, is a widely used scintillator material due to its exceptional X-ray attenuation efficiency and high light yield. However, Gadox-based scintillators suffer from low X-ray spatial resolution due to their large particle size, which causes significant light scattering. To address this limitation, we report the synthesis of terbium-doped colloidal Gadox nanoplatelets (NPLs) with near-unity photoluminescence quantum yield (PLQY) and high radioluminescence light yield (LY). In particular, our investigation reveals a strong correlation between PLQY, LY, particle size, and Tb3+concentration. Our synthetic approach allows precise control over the lateral size and thickness of the Gadox NPLs, resulting in a LY of 50,000 photons/MeV. Flexible scintillating screens fabricated with the solution-processable Gadox NPLs exhibited a 20 lp/mm X-ray spatial resolution, surpassing commercial Gadox scintillators. These high-performance and flexible Gadox NPL-based scintillators enable enhanced X-ray imaging capabilities in medicine and security. Our work provides a framework for designing nanomaterial scintillators with superior spatial resolution and efficiency through precise control of dimensions and dopant concentration.

Organic-Inorganic Hybrid Glasses of Atomically Precise Nanoclusters.

Organic-inorganic atomically precise nanoclusters provide indispensable building blocks for establishing structure-property links in hybrid condensed matter. However, robust glasses of ligand-protected nanocluster solids have yet to be demonstrated. Herein, we show [Cu4I4(PR3)4] cubane nanoclusters coordinated by phosphine ligands (PR3) form robust melt-quenched glasses in air with reversible crystal-liquid-glass transitions. Protective phosphine ligands critically influence the glass formation mechanism, modulating the glasses' physical properties. A hybrid glass utilizing ethyldiphenylphosphine-based nanoclusters, [Cu4I4(PPh2Et)4], exhibits superb optical properties, including >90% transmission in both visible and near-infrared wavelengths, negligible self-absorption, near-unity quantum yield, and high light yield. Experimental and theoretical analyses demonstrate the structural integrity of the [Cu4I4(PPh2Et)4] nanocluster, i.e., iodine-bridged tetranuclear cubane, has been fully preserved in the glass state. The strong internanocluster CH-π interactions found in the [Cu4I4(PPh2Et)4] glass and subsequently reduced structural vibration account for its enhanced luminescence properties. Moreover, this highly transparent glass enables performant X-ray imaging and low-loss waveguiding in fibers drawn above the glass transition. The discovery of "nanocluster glass" opens avenues for unraveling glass formation mechanisms and designing novel luminescent glasses of well-defined building blocks for advanced photonics.

Real-Time Tracking of Hot Carrier Injection at the Interface of FAPbBr3 Perovskite Using Femtosecond Mid-IR Spectroscopy.

One of the most effective approaches to optimizing the performance of perovskite solar cells is to fully understand the ultrafast carrier dynamics at the interfaces between absorber and transporting layers at both the molecular and atomic levels. Here, the injection dynamics of hot and relaxed charge carriers at the interface between the hybrid perovskite, formamidinium lead bromide (FAPbBr3), and the organic electron acceptor, IEICO-4F, are investigated and deciphered by using femtosecond (fs) mid-infrared (IR), transient absorption (TA), and fluorescence spectroscopies. The visible femtosecond-TA measurements reveal the generation of hot carriers and their transition to free carriers in the pure FAPbBr3 film. Meanwhile, the efficient extraction of hot carriers in the mixed FAPbBr3/IEICO-4F film is clearly evidenced by the complete disappearance of their spectral signature. More specifically, the time-resolved results reveal that hot carriers are injected from FAPbBr3 to IEICO-4F within 150 fs, while the transfer time for the relaxed carriers is about 205 fs. The time-resolved mid-IR experiments also demonstrate the ultrafast formation of two peaks at 2115 and 2233 cm-1, which can be attributed to the C≡N symmetrical and asymmetrical vibrational modes of anionic IEICO-4F, thus providing crystal clear evidence for the electron transfer process between the donor and acceptor units. Moreover, photoluminescence (PL) lifetime measurements reveal an approximately 10-fold decrease in the donor lifetime in the presence of IEICO-4F, thereby confirming the efficient electron injection from the perovskite to the acceptor unit. In addition, the efficient electron injection at the FAPbBr3/IEICO-4F interface and its impact on the C≡N bond character are experimentally evidenced and align with density functional theory (DFT) calculations. This work offers new insights into the electron injection process at the FAPbBr3/IEICO-4F interface, which is crucial for developing efficient optoelectronic devices.

Atomically Precise Defective Copper Nanocluster Catalysts for Highly Selective C-C Cross-Coupling Reactions.

Point defects in nanoparticles have long been hypothesized to play an important role in governing the particle's electronic structure and physicochemical properties. However, single point defects in material systems usually exist with other heterogeneities, obscuring the chemical role of the effects. Herein, we report the synthesis of novel atomically precise, copper hydride nanoclusters (NCs), [Cu28 H10 (C7 H7 S)18 (TPP)3 ] (Cu28 ; TPP: triphenylphosphine; C7 H7 S: o-thiocresol) with a defined defect in the gram scale via a one-pot reduction method. The Cu28 acts as a highly selective catalyst for C-C cross-couplings. The work highlights the potential of defective NCs as model systems for investigating individual defects, correlating defects with physiochemical properties, and rationally designing new nanoparticle catalysts.

Activated Carbon from Palm Date Seeds for CO2 Capture.

The process of carbon dioxide capture and storage is seen as a critical strategy to mitigate the so-called greenhouse effect and the planetary climate changes associated with it. In this study, we investigated the CO2 adsorption capacity of various microporous carbon materials originating from palm date seeds (PDS) using green chemistry synthesis. The PDS was used as a precursor for the hydrochar and activated carbon (AC). Typically, by using the hydrothermal carbonization (HTC) process, we obtained a powder that was then subjected to an activation step using KOH, H3PO4 or CO2, thereby producing the activated HTC-PDS samples. Beyond their morphological and textural characteristics, we investigated the chemical composition and lattice ordering. Most PDS-derived powders have a high surface area (>1000 m2 g-1) and large micropore volume (>0.5 cm3 g-1). However, the defining characteristic for the maximal CO2 uptake (5.44 mmol g-1, by one of the alkaline activated samples) was the lattice restructuring that occurred. This work highlights the need to conduct structural and elemental analysis of carbon powders used as gas adsorbents and activated with chemicals that can produce graphite intercalation compounds.