Jingwei Li's research while affiliated with Chongqing University and other places

Hydrodeoxygenation (HDO) of lignin derivatives at room‐temperature (RT) is still of challenge due to the lack of satisfactory activity reported in previous literature. Here, it is successfully designed a Pd/UiO‐66‐(COOH) 2 catalyst by using UiO‐66‐(COOH) 2 as the support with uncoordinated carboxyl groups. This catalyst, featuring a moderate Pd loading, exhibited exceptional activity in RT HDO of vanillin (VAN, a typical model lignin derivative) to 2‐methoxyl‐4‐methylpheonol (MMP), and >99% VAN conversion with >99% MMP yield is achieved, which is the first metal‐organic framework (MOF)‐based catalyst realizing the goal of RT HDO of lignin derivatives, surpassing previous reports in the literature. Detailed investigations reveal a linear relationship between the amount of uncoordinated carboxyl group and MMP yield. These uncoordinated carboxyl groups accelerate the conversion of intermediate such as vanillyl alcohol (VAL), ultimately leading to a higher yield of MMP over Pd/UiO‐66‐(COOH) 2 catalyst. Furthermore, Pd/UiO‐66‐(COOH) 2 catalyst also exhibits exceptional reusability and excellent substrate generality, highlighting its promising potential for further biomass utilization.

Environmentally friendly tin (Sn) perovskites have received considerable attention due to their great potential for replacing their toxic lead counterparts in applications of photovoltaics and light-emitting diodes (LEDs). However, the device performance of Sn perovskites lags far behind that of lead perovskites, and the highest reported external quantum efficiencies of near-infrared Sn perovskite LEDs are below 10%. The poor performance stems mainly from the numerous defects within Sn perovskite crystallites and grain boundaries, leading to serious non-radiative recombination. Various epitaxy methods have been introduced to obtain high-quality perovskites, although their sophisticated processes limit the scalable fabrication of functional devices. Here we demonstrate that epitaxial heterodimensional Sn perovskite films can be fabricated using a spin-coating process, and efficient LEDs with an external quantum efficiency of 11.6% can be achieved based on these films. The film is composed of a two-dimensional perovskite layer and a three-dimensional perovskite layer, which is highly ordered and has a well-defined interface with minimal interfacial areas between the different dimensional perovskites. This unique nanostructure is formed through direct spin coating of the perovskite precursor solution with tryptophan and SnF2 additives onto indium tin oxide glass. We believe that our approach will provide new opportunities for further developing high-performance optoelectronic devices based on heterodimensional perovskites.

The investigation of the oxidation behavior of van der Waals chalcogenides holds significant importance in terms of preventing and controlling oxidation, utilizing surface oxidation structures to regulate properties, and advancing applications. Here, taking GaSe as a candidate, its thermal oxidation and surface structure evolution are intensively studied. Through systematic microscopic analyses, oxidized structures at multi‐scale (from atomic scale to millimeters) are resolved, and various assembly heterogeneous surfaces including Ga2Se3/Ga2O3 and Ga2O3 multilayers are uncovered at different oxidation temperatures. The temperature‐dependent oxidation behavior and surface structure evolution of the GaSe are revealed, and the oxidation mechanisms in the entire temperature range are also disclosed. Finally, the photoluminescence regulation of the GaSe is initially explored via thermal oxidation, demonstrating great potential for surface oxidation engineering. This study is not only of great importance for the deep understanding and utilization of GaSe oxidation, but also beneficial for materials/device design and development of relative systems.

The susceptibility to moisture of metal-organic frameworks (MOFs) is a critical bottleneck for their wider practical application. Constructing core-shell composites has been postulated as an effective strategy for enhancing moisture resistance, but for fragile MOFs this has rarely been accomplished. We report herein, for the first time, the construction of a customized hydrophobic porous shell, NTU-COF, on the particularly fragile MOF-5 by a "Plug-Socket Anchoring" strategy. Notably, the pore structure of MOF-5 was well maintained, and it could still achieve complete CO2/N2 separation under humid conditions. The homogeneous interface between MOF-5 and NTU-COF has been inspected at atomic resolution by a combination of cryogenic focused ion beam (cryo-FIB) and ultralow-dose (scanning) transmission electron microscope giving profound insight into the mechanism of assembly of the core-shell structure. This work presents a facile strategy for the fabrication of a hydrophobic porous shell for labile MOFs, and provides a general approach for solving the problem of moisture instability of porous materials for practical applications.

The main bottlenecks limiting the photovoltaic performance and stability of inverted perovskite solar cells (PSCs) are trap-assisted non-radiative recombination losses and photochemical degradation at the interface between perovskite and charge-transport layers. We propose a strategy to manipulate the crystallization of methylammonium-free perovskite by incorporating a small amount of 2-aminoindan hydrochloride into the precursor inks. This additive also modulates carrier recombination and extraction dynamics at the buried interface via the formation of a bottom-up two-dimensional/three-dimensional heterojunction. The resultant inverted PSC achieves a power conversion efficiency of 25.12% (certified 24.6%) at laboratory scale (0.09 cm²) and 22.48% at a larger area (1 cm²) with negligible hysteresis. More importantly, the resulting unencapsulated devices show superior operational stability, maintaining >98% of their initial efficiency of >24% after 1,500 hours of continuous maximum power point tracking under simulated AM1.5 illumination. Meanwhile, the encapsulated devices retain >92% of initial performance for 1,200 hours under the damp-heat test (85 °C and 85% relative humidity).

Although isomerism is a typical and significant phenomenon in organic chemistry, it is rarely found in covalent organic framework (COF) materials. Herein, for the first time, we report a controllable synthesis of topological isomers in three-dimensional COFs via a distinctive tetrahedral building unit under different solvents. Based on this strategy, both isomers with a dia or qtz net (termed JUC-620 and JUC-621) have been obtained, and their structures are determined by combining powder X-ray diffraction and transmission electron microscopy. Remarkably, these architectures show a distinct difference in their porous features; for example, JUC-621 with a qtz net exhibits permanent mesopores (up to ∼23 Å) and high surface area (∼2060 m2 g-1), which far surpasses those of JUC-620 with a dia net (pore size of ∼12 Å and surface area of 980 m2 g-1). Furthermore, mesoporous JUC-621 can remove dye molecules efficiently and achieves excellent iodine adsorption (up to 6.7 g g-1), which is 2.3 times that of microporous JUC-620 (∼2.9 g g-1). This work thus provides a new way for constructing COF isomers and promotes structural diversity and promising applications of COF materials.