Publications by authors named "Zongju Cheng"
Solid-state electrolytes (SSEs) are crucial to high-energy-density lithium metal batteries, but they commonly suffer from slow Li transfer kinetics and low mechanical strength, severely hampering the application for all-solid-state batteries. Here, we develop a two-dimensional (2D) high-entropy lithium-ion conductor, lithium-containing transition-metal phosphorus sulfide, HE-LiMPS (Li(FeCoNiMnZn)PS) with five transition-metal atoms and lithium ions (Li) dispersed into [PS] framework layers, exhibiting high lattice distortions and a large amount of cation vacancies. Such unique features enable to efficiently accelerate the migration of Li in 2D [PS] interlamination, delivering a high ionic conductivity of 5 × 10 S cm at room temperature.
View Article and Find Full Text PDFArticle Synopsis
- Current interconnect insulators like silicon dioxide have high dielectric constants (≈4), leading to issues like parasitic capacitance and slower response times in integrated circuits.
- Researchers developed a novel thin film of amorphous carbon nitride (a-CN) using a specific process involving MXene-Ti CNT and bromine vapor, which resulted in an ultra-low dielectric constant of 1.69 at 100 kHz.
- The a-CN film also demonstrates a high breakdown strength of 5.6 MV/cm, indicating significant potential for use in future integrated circuit technology.
Although 2D transition metal carbides and nitrides (MXenes) have fantastic physical and chemical properties as well as wide applications, it remains challenging to produce stable MXenes due to their rapid structural degradation. Here, unique metal-bonded atomic layers of transition metal carbides with high stabilities are produced via a simple topological reaction between chlorine-terminated MXenes and selected metals, where the metals enable them to not only remove partially Cl terminations, but also bond with adjacent atomic MXene slabs, driven by the symmetry of MAX phases. The films constructed from Al-bonded Ti C Cl atomic layers show high oxidation resistance up to 400 °C and low sheet resistance of 9.
View Article and Find Full Text PDFAlthough transition metal dichalcogenides (TMDs) monolayers are widely applied in electronics, optics, catalysis, and energy storage, their yield or output is commonly very low (<1 wt % or micrometer level) based on the well-known top-down (, exfoliation) and bottom-up (, chemical vapor deposition) approaches. Here, 1T MoS monolayers with a very high fraction of ∼90% were achieved the conversion of Mo-based MXenes (MoCT and MoCT) at high temperatures in hydrogen sulfide gas, in which the Mo-layer of Mo-based MXenes could be transformed to MoS monolayers and the Mo vacancies facilitate the gliding of sulfur layers to form 1T MoS. The resultant 1T MoS monolayers with numerous vacancies exhibit strong chemisorption and high catalytic activity for lithium polysulfides (LiPSs), delivering a reversible capacity of 736 mAh g at 0.
View Article and Find Full Text PDFArticle Synopsis
- Single atom catalysts show improved electrocatalytic activity for chemical reactions due to better geometric and electronic structures compared to bulk catalysts.
- Researchers developed a method to create single atom copper immobilized MXene that effectively reduces CO to methanol through selective etching of aluminum in hybrid A layers, preserving copper atoms.
- The new single atom Cu catalyst demonstrated a high Faradaic efficiency of 59.1% for producing methanol and exhibited strong electrocatalytic stability, attributed to its unique unsaturated electronic structure which lowers energy barriers for critical reaction steps.