KAUST Catalysis Center (KCC)

Compressive strain engineering improves perovskite stability. Two-dimensional compressive strain along the in-plane direction can be applied to perovskites through the substrate; however, this in-plane strain results in an offsetting tensile strain perpendicular to the substrate, linked to the positive Poisson ratio of perovskites. Substrate-induced strain engineering has not yet resulted in state-of-the-art operational stability. Here, we seek instead to implement hydrostatic strain in perovskites by embedding lattice-mismatched perovskite quantum dots (QDs) into a perovskite matrix. QD-in-matrix perovskites show a homogeneously strained lattice as evidenced by grazing-incidence X-ray diffraction. We fabricate mixed-halide wide-band-gap (Eg; 1.77 eV) QD-in-matrix perovskite solar cells that maintain >90% of their initial power conversion efficiency (PCE) after 200 h of one-sun operation at the maximum power point (MPP), a significant improvement relative to matrix-only devices, which lose 10% (relative) of their initial PCE after 5 h of MPP tracking.

Abstract: Developing fluorescence porous probe for detecting and eliminating Cu2+ contamination in water or biosystem is an essential research project that has attracted considerable attention. However, improving the fluorescence detecting efficiency while enhancing the adsorption capacity of the porous probe is of great challenge. Herein, a bifunctional two-dimensional imine-based porous covalent organic framework (TTP-COF) probe was designed and synthesized from 1,3,5-tris (4-aminophenyl) benzene (TAPB) and 2,4,6-Triformylphloroglucinol (TP) ligand. TTP-COF displayed rapid detection of Cu2+ (limit of detection (LOD) = 10 nmol·L−1 while achieving a high adsorption capacity of 214 mg·g−1 (pH = 6) at room temperature with high reusability (> 5 cycles). The key roles and contributions of high π-conjugate and delocalized electrons in TABP and functional –OH groups in TP were proved. More importantly, the fluorescence quenching mechanism of TTP-COF was studied by density functional theory theoretical calculations, revealing the crucial role of intramolecular hydrogen bonds among C=N and –OH groups and the blocking of the excited state intramolecular proton transfer process in detecting process of Cu2+. Graphical abstract: [Figure not available: see fulltext.].

Understanding the correlation between the structural evolution of electrocatalysts and their catalytic activity is both essential and challenging. In this study, we investigate this correlation in the context of the oxygen evolution reaction (OER) by examining the influence of structural disorder during/after the dynamic structural evolution on their OER activity of Fe-Ni (oxy)hydroxide catalysts using operando X-ray absorption spectroscopy, alongside other experiments and theoretical calculations. The Debye-Waller factors obtained from extended X-ray absorption fine structure analyses reflect the degree of structural disorder and exhibit a robust correlation with the intrinsic OER activities of the electrocatalysts. Enhanced OER activity of in-situ generated metal (oxy)hydroxides derived from different pre-catalysts is linked to increased structural disorder, offering a promising approach for designing efficient OER electrocatalysts. This strategy may inspire similar investigations in related electrocatalytic energy-conversion systems.

Activating O–H bonds in β,γ-unsaturated oximes is challenging due to high redox potential. Our method combines HAT and photoredox catalysis to allow the synthesis of diverse heterocycles using various radical acceptors. Mechanistic studies support the HAT process in O–H bond activation.

Well-defined multicrystalline multiblock polymers are essential model polymers for advancing crystallization physics, phase separation, self-assembly, and improving the mechanical properties of materials. However, due to different chain properties and incompatible synthetic methodologies, multicrystalline multiblock polymers with more than two crystallites are rarely reported. Herein, by combining polyhomologation, ring-opening polymerization, and catalyst switch strategy, we synthesized a pentacrystalline pentablock quintopolymer, polyethylene-b-poly(ethylene oxide)-b-poly(ε-caprolactone)-b-poly(L-lactide)-b-polyglycolide (PE-b-PEO-b-PCL-b-PLLA-b-PGA). The fluoroalcohol-assisted catalyst switch enables the successful incorporation of a high melting point polyglycolide block into the complex multiblock structure. Solid-state nuclear magnetic resonance spectroscopy, X-ray diffraction, and differential scanning calorimetry revealed the existence of five different crystalline phases.