Wei Liu

Molten-salt chemical vapor deposition (CVD), using water-soluble metal salts such as Na2MoO4 and Na2WO4 as precursors, has emerged as an important strategy for growing high-quality transition metal dichalcogenides (TMDCs). Although generally regarded as a liquid-mediated process, the role of precursor volatilization remains unclear. Here, an in situ optical visualization CVD platform directly tracks Na2WO4 precursor evolution during monolayer WS2 growth. By tuning the growth temperature, two distinct growth regimes, namely weak-volatilization and strong-volatilization regimes, are identified. Under the weak-volatilization, persistent liquid droplets drive nonuniform lateral expansion, producing irregular domain morphologies and high substrate coverage. In contrast, enhanced vapor-phase precursor transport produces smoother domain edges but lower coverage. Atomic-scale characterization further reveals regime-dependent edge structure evolution and structural uniformity. These findings demonstrate that Na2WO4-mediated WS2 growth is governed by the competition between precursor retention and volatilization rather than retained liquid intermediates alone, establishing a general framework for understanding crystal growth in molten-salt CVD.

Electron acceptors such as tetracyanoquinodimethane (TCNQ) and its fluorinated analogue F4TCNQ are foundational to charge-transfer and doping chemistry. At interfaces formed by deposition of these acceptors onto donor substrates, reduced anionic species can naturally coexist with unreacted neutral acceptors, creating mixed-valence environments beyond conventional one-way charge transfer. Here, we report charge-resonance polymerization of acceptors at donor–acceptor interfaces. Deposition of neutral acceptors onto electron-donor substrates partially reduces the acceptors to anion salts, establishing neutral/radical-anion contact. This mixed-valence interface enables cyclic neutral–anion charge-resonance interactions that initiate a self-propagating polymerization process. This dynamic process operates across diverse donor substrates and from room temperature to 250 °C, producing large-area membranes up to 30 × 30 cm with persistent radicals and room-temperature magnetic hysteresis. These findings establish intraspecies charge resonance as a design principle for self-activating polymerization and offer fresh insight into charge behavior at donor–acceptor interfaces.

Pyridinic nitrogen lowers debromination temperature, enabling solid-state polymerization into a nitrogen-rich polymer for high-performance lithium storage.

Aqueous copper‐ion batteries are attractive for their cost, safety, and sustainability but are limited by a narrow voltage window and modest rate performance. A coupled‐redox strategy is proposed in which the organic molecular cathode 7,7,8,8‐ tetracyanoquinodimethane (TCNQ) and Cu ²⁺ each accept one electron to form TCNQ ^– and Cu ⁺ , which then coordinate into a conductive CuTCNQ phase formed in situ. This phase accelerates charge transport and stabilizes the redox process, delivering a specific capacity of 171 mAh g ⁻¹ at 0.5 A g ⁻¹ . Owing to the fast kinetics of CuTCNQ, the cell retains a specific capacity of 82 mAh g ⁻¹ after 700 cycles at a high current density of 5 A g ⁻¹ . Extending the concept to a decoupled Zn//TCNQ aqueous battery with a TCNQ cathode and Zn anode yields an operating voltage of 1.32 V. These results show that pairing an organic‐molecule with Cu ²⁺ to form a conductive coordination phase is an effective route to high‐rate, long‐life aqueous copper‐ion storage and broadens the role of organic electrodes in aqueous batteries.

Scalable fabrication of multiple quantum-well (MQW) superlattices via layer-by-layer stacking of two-dimensional (2D) materials remains challenging. Here, we propose a plasma-assisted electrochemical intercalation strategy to overcome this limitation. By intercalating 1-ethyl-3-methylimidazolium (EMIM⁺) cations into multilayer molybdenum disulfide (MoS₂), followed by oxygen plasma intercalation, we achieve large-area (∼100 μm) MQW superlattices with hundreds of active layers. This approach enhances MoS₂ photoluminescence (PL) by 2 orders of magnitude, with the PL quantum yield (PLQY) increasing with both excitation power and thickness. The enhancement arises from interlayer-decoupling-induced bandgap directness and electron extraction induced by oxygen plasma, effectively suppressing charge transfer between heterointerfaces. Our findings provide a scalable route for fabricating quasi-MQW superlattices, opening new avenues for photophysics research and next-generation optoelectronics.

The integration of renewable energy sources, such as solar and wind, requires efficient energy storage systems. Aqueous batteries, with their safety, low cost, and flexibility, have gained attention as promising solutions for energy storage. In this study, we developed an aqueous copper-ion storage device based on an iron hexacyanoferrate (FeHCF) cathode, which offers high capacities of 190 mA h g⁻¹ at 1 A g⁻¹ and 102 mA h g⁻¹ even at 3 A g⁻¹, with a discharge plateau at 0.59 V vs. SHE and a low polarization voltage of 0.2 V. In situ XRD, Raman, and XPS characterization techniques show that copper-ion insertion induces structural changes in FeHCF, leading to a valence state transition between Fe²⁺ and Fe³⁺, with a partial conversion of Cu²⁺ to Cu⁺. To improve the working voltage, we replaced the Cu²⁺/Cu⁰ anode reaction with the lower potential Zn/Zn(OH)₄ ²⁻ reaction, achieving an aqueous battery with a voltage range of 1.6–2.5 V. These findings highlight FeHCF-based aqueous batteries’ potential for high-performance and safe energy storage.

In this study, ultrathin conjugated microporous thermoset nanosheets are synthesized using a thermally initiated polymerization strategy and investigated as anode materials for Li-ion storage. The resulting nanosheets demonstrate a discharging capacity of ∼545.2 mA h g⁻¹ at 0.5 A g⁻¹ and maintain a reversible capacity of ∼329.3 mA h g⁻¹ at 3.0 A g⁻¹ over 1500 cycles. Electrochemical reaction mechanism studies indicate that the π-conjugated network structure, featuring nitrogen-decorated pores and edges, facilitates exceptionally stable and reversible electrochemical lithiation processes.

In this study, we have created and investigated ultrathin, large‐size two‐dimensional C₂N nanosheets, which serve as promising anode materials for sodium ion batteries. Those ultrathin C₂N nanosheets were produced through a chemical vapor deposition process, involving the polymerization of the precursor molecule HAT‐CN on sodium chloride templates. Notably, these nanosheets inherit an abundance of nitrogen sites from the precursor molecules, which are highly advantageous for sodium ion storage. In addition, the ultrathin nature of these nanosheets leads to significantly shorter ion transport pathways, enhancing their capacity for rapid ion storage compared to C₂N particles. As a result, the anode constructed using C₂N nanosheets demonstrates a notably higher capacity of 335.1 mAh g⁻¹ at 0.5 A g⁻¹, outperforming the 211.5 mAh g⁻¹ of C₂N particles. Furthermore, it exhibits outstanding rate performance, achieving 255.4 mAh g⁻¹ at a current density of 2.0 A g⁻¹, along with excellent cycle stability, maintaining a reversible capacity retention of 92.9 % over 1500 cycles at 2.0 A g⁻¹. This research introduces a novel approach to developing high‐capacity anode materials for sodium storage by utilizing carbon nitride materials.

Integrating reactive radicals into membranes that resemble biological membranes has always been a pursuit for simultaneous organics degradation and water filtration. In this research, we discovered that a radical polymer (RP) that can directly trigger the oxidative degradation of sulfamethozaxole (SMX). Mechanistic studies by experiment and density functional theory simulations revealed that peroxyl radicals are the reactive species, and the radicals could be regenerated in the presence of O ₂ . Furthermore, an interpenetrating RP network membrane consisting of polyvinyl alcohol and the RP was fabricated to demonstrate the simultaneous filtration of large molecules in the model wastewater stream and the degradation of ~ 85% of SMX with a steady permeation flux. This study offers valuable insights into the mechanism of RP-triggered advanced oxidation processes and provides an energy-efficient solution for the degradation of organic compounds and water filtration in wastewater treatment.