Yousong Gu

Two-dimensional (2D) van der Waals (vdWs) magnetic materials provide an ideal platform for exploring long-range magnetic ordering at the 2D limit and show promising applications in next-generation spintronics devices. In this works, VCl 2 / WTe 2 vdWs heterostructures are investigated to study the electronic structure and magnetic anisotropy, as well as their modulation via external electric field and biaxial strain in the plane based on first-principles calculations. The results show that the VCl 2 / WTe 2 heterostructure is semiconducting with a band gap of 0.82 eV, a 0.4 meV valley splitting and a system magnetic anisotropy energy (MAE) of 0.033 mJ m − 2 (2.61 meV/f.u.) after taking into account of spin–orbital coupling. The application of bi-axial strain and vertical electric field to the heterostructures changes the electronic structure. A maximum MAE of −0.5 mJ m − 2 (−39.55 meV/f.u.) and a maximum valley splitting value (4.9 meV) are found for the VCl 2 / WTe 2 heterostructures at a strain of −6%. The system MAE reaches 3.2 mJ m − 2 (253 meV/f.u.) at an electric field strength of 0.3 V Å⁻¹, and reaches 0.96 mJ m − 2 (75.9 meV/f.u.)at −0.3 V Å⁻¹. It also reaches a maximum valley splitting of 3.53 meV. Under the modulation of biaxial strains and positive and negative electric fields, the VCl 2 / WTe 2 heterostructures have significant tunable electronic structure and magnetic anisotropy, which suggests that the VCl 2 / WTe 2 heterostructure has potential applications in spintronic devices.

Lithium (Li) is a promising anode material for all‐solid‐state Li metal batteries (ASSLMBs) due to its high energy density. However, the interface incompatibility of Li/solid electrolyte and uneven Li deposition induces the penetration of Li dendrites. Herein, a multifunctional rich‐LiF/Mg artificial solid electrolyte interphase (SEI) layer is constructed from a MgF₂‐PVDF‐HFP film to passivate the Li anode and achieve effective inhibition of Li dendrites. Notably, the triggered Li_xMg alloys rivet the Li₆PS₅Cl (LPSCl) electrolyte and Li anode together well, producing satisfactory interface contact and reducing overpotential. The mechanism of LiF and Li_xMg alloys to enhance the stability of the Li/LPSCl interface is further elucidated by density functional theory (DFT). Moreover, the synergistic interaction of LiF with high interfacial energy and Li_xMg alloys with low diffusion barrier promotes uniform deposition of Li during plating/stripping and structural stability. Therefore, the modified Li‐symmetric cell exhibits ultra‐high critical current density (2.0 mA cm⁻²) and considerable cyclic stability (more than 1000 h at 0.5 mA cm⁻²). Remarkably, NCM//LPSCl//3% MgF₂‐PVDF‐HFP@Li ASSLMBs exhibit considerable long‐term cycle stability (86.9% capacity retention after 100 cycles at 0.2 C). This work highlights the critical role of the intermediate passivating layer in mitigating side reactions and preventing Li penetration.

A growth-limited and self-polymerizing carbon layer-coated fluoride electrode creates refined nanodomains during cycling that cooperate with amorphous phases to promote Li⁺ conduction, providing excellent cycling life and specific capacity.

Sulfide solid electrolytes (SSEs) have become an ideal candidate material for all‐solid‐state Li metal batteries (ASSLMBs) because of their high ionic conductivity. However, the vile Li incompatibility and poor air stability of SSEs barriers their commercial application. Herein, novel Li_6+2xP_1−xIn_xS_5−1.5xO_1.5xCl (0 ≤ x ≤ 0.1) SSEs are synthesized via In and O co‐doped Li₆PS₅Cl. By regulating the substitution concentration, the prepared Li_6.12P_0.92In_0.08S_4.88O_0.12Cl exhibits considerable ionic conductivity (2.67 × 10⁻³ S cm⁻¹) and enhanced air stability. Based on the first‐principles density functional theory (DFT) calculation, it is predicted that In³⁺ replaces P⁵⁺ to form InS₄⁵⁻ tetrahedron and O²⁻ replaces S²⁻ to form PS₃O⁴⁻ group. The mechanism of enhancing air stability by In, O co‐substituting Li₆PS₅Cl is clarified. More remarkably, the formation of Li‐In alloys induced by Li_6.16P_0.92In_0.08S_4.88O_0.12Cl electrolyte at the anode interface is beneficial to reducing the migration barrier of Li‐ions, promoting their remote migration, and enhancing the stability of the Li/SSEs interface. The optimized electrolyte shows superior critical current density (1.4 mA cm⁻²) and satisfactory Li dendrite inhibition (stable cycle at 0.1 mA cm⁻² over 3000 h). The ASSLMBs with Li_6.16P_0.92In_0.08S_4.88O_0.12Cl electrolyte reveal considerable cycle stability. This work emphasizes In, O co‐doping to address redox issues of sulfide electrolytes.

The photogalvanic effect (PGE) generated under linearly polarized light irradiation has remarkable applications in 2D nanodevices. The PGE of 2D WS₂/Mo₂CF₂ van der Waals (vdW) heterostructure can generate photocurrent and high sensitivity to polarized light. However, the PGE has less photogenerated current. On this basis, the photocurrent transport mechanism of PGE under low bias voltage is investigated. The results show that the photocurrent of the photon energy has , and dependence on the polarization angle θ under the considered external bias voltage. Under a bias voltage of 1.0 V, the maximum photocurrent of 3.7 eV photon energy in the zigzag direction can reach 4.61. Under a bias voltage of 1 V, the maximum photocurrent of 1.8 eV photon energy in the armchair direction can reach 6.71. The maximum photocurrents are in the order of 10⁻¹ for both zigzag and armchair directions with 0 V bias. Furthermore, 2D WS₂/Mo₂CF₂ vdW heterostructure has a stable and high extinction ratio. These results show that 2D WS₂/Mo₂CF₂ vdW heterostructure is a potential candidate material for future optoelectronics in the visible light region.

With the increasing demand for renewable energy and clean energy, photocatalysis is considered an economical and feasible source of energy. In this work, we select two-dimensional (2D) materials of X₂CT₂ (X = Cr, Hf, Mo, Sc, Ti, Zr; T = Cl, F, O, OH), Mxene, and MS₂ (M = Mo, W) to form 20 systems of 2D van der Waals (vdW) heterostructures. We establish five screening steps, and the 2D Mo₂CF₂/WS₂ vdW heterostructures meet all the screening conditions. Mo₂CF₂/WS₂ is a type II semiconductor with a band gap of 1.58 eV, proper band edge position and high solar-to-hydrogen efficiency (17.15%) and power conversion efficiency (23.4%). An excellent electron-hole recombination time of 21.2 ps and electron (hole) migration time of 149 (265) fs are obtained in the 2D Mo₂CF₂/WS₂ vdW heterostructure. In addition, the calculation results of Gibbs free energy show that a hydrogen reduction reaction and water oxidation reaction can proceed smoothly under the driving of photogenerated holes.

Two-dimensional (2D) van der Waals (vdW) heterostructures have attracted much attention due to their unique properties in photocatalysis, electronics, and energy storage. This work comprehensively analyzed the electronic properties and photocatalytic efficiency properties of 2D vdW MoS₂/Hf₂CO₂ heterostructure by first-principles calculations and molecular dynamics simulation. An ideal band gap of 1.44 eV was found for visible light absorption. Meanwhile, a high solar-to-hydrogen efficiency of 17.14% is obtained from the calculated band-edge positions, and a high power conversion efficiency of 13.84% is also confirmed by spectroscopy limited maximum efficiency simulation. We estimate the time scale for electron–hole transfer and recombination times using a combination of non-adiabatic molecular dynamics and time-dependent density functional theory. A suitable e-h recombination time of 1.86 ns and electron (hole) transfer time of 331 (978) fs are obtained in the 2D MoS₂/Hf₂CO₂ heterostructure, which is expected to ensure high photocatalytic efficiency. Therefore, the constructed MoS₂/Hf₂CO₂ heterostructures provide a new example for the prediction of high-performance nano optoelectronic devices.

A strong metal-support interaction (SMSI) type catalyst has been synthesized and applied to a molten hydroxide direct carbon fuel cell (MHDCFC) to enhance the reaction activity of the anode carbon fuel through the interaction between the metal Ni and the support CeO₂. Two catalysts have been prepared by a direct precipitation method (denoted NiO@CeO₂) and a hydrothermal method (denoted NiO-CeO₂), which are reduced by H₂ to obtain Ni@CeO₂ and Ni-CeO₂, respectively. X-ray photoelectron spectroscopy (XPS), Raman, and temperature-programmed hydrogen reduction (H₂-TPR) analysis results show that there are obvious oxygen vacancies and a Ni-O-Ce interface structure in NiO-CeO₂ and Ni-CeO₂, which is induced by the interaction between Ni and CeO₂. The calculation results of current density and power density show that the performance of the MHDCFC is significantly improved in the presence of Ni-CeO₂. The function fitting curves of the logarithm of the reaction rate constant (ln k) and the reciprocal of the temperature (1/T) show that the slope of the curve is decreased significantly after the addition of Ni-CeO₂. In combination with density functional theory (DFT), the anode carbon reaction path is simulated in the MHDCFC, and the calculation results show that the reaction energy for the anodic carbon to generate carbon dioxide is decreased by 1.03 eV in the presence of Ni-CeO₂.

Here we report an Ag-modified Cu/CuO (Cu/CuO–Ag) catalyst with a porous 3D structure, which can efficiently electrochemically reduce CO₂ to ethylene and other C₂₊ products.