Gang Liu

The catalytic performance of PtN ₂ doped single transition metal atoms in the OER, ORR and HER is studied using density functional theory.

High-speed rotating flywheel bearings, designed for space applications, generate a high-resistance hydrodynamic lubrication film, which isolates the rotor, transforming it into a conductor. This phenomenon introduces a novel failure mode—flywheel bearing electrical damage caused by space charging effects. This paper first reviews the sources of common shaft voltages in flywheels and the mechanisms of electrical damage and improves the principle of deep charge causing shaft voltages in flywheel bearings, proposing that surface charge is another source of shaft voltages. The quantified analysis model of flywheel bearing electrical damage in relation to rotational speed and high-energy electron flux is derived, indicating that the damage caused by space charge–discharge to the bearing is of small magnitude and only becomes apparent after long-term accumulation, thus being easily overlooked. Based on the causal chain of electrical damage, a correlation analysis model consistent with physical principles is constructed, and the correlation between on-orbit anomalies of the flywheel and high-energy electron flux is confirmed through the use of big data. Preliminary experiments are conducted to validate all of the research results. Finally, suggestions are given for the reliable design, application, and testing of flywheels.

This study designs a high-performance GeC/SGaSnP Z-scheme photocatalyst with excellent charge separation, strong visible light absorption, and superior HER/OER activity, making it a promising candidate for efficient water splitting.

The design of photonic crystals using novel materials holds significant importance in constructing high-performance, next-generation photonic crystal devices. In this study, aiming at the requirements for enhanced transmission and selectivity, we utilized a topology optimization method based on the method of moving asymptotes (MMA) to realize a high-temperature superconducting photonic crystal power splitter with low transmission loss and selectivity effects, which allows for flexible control and manipulation of optical signals. The method addresses the shortcomings of traditional scanning techniques, such as low efficiency and high resource consumption, by allowing for multi-parameter optimization. This improvement enhances the precision and effectiveness of the numerical computational iterative process. The research offers insights into the design of novel optical devices.

We used first-principles methods to investigate how oxygen vacancy defects affect the optical properties of YBa₂Cu₃O_7−δ (0 < δ < 1). Oxygen vacancies can be used as a tool to manipulate the optical response of YBa₂Cu₃O_7−δ.

Photonic crystal structures have excellent optical properties, so they are widely studied in conventional optical materials. Recent research shows that high-temperature superconducting periodic structures have natural photonic crystal features and they are favourable candidates for single-photon detection. Considering that superconductors have completely different properties from conventional optical materials, we study the energy level diagram and mid-infrared 3 μm–5 μm transmission spectrum of two-dimensional superconducting photonic crystals in both superconducting and quenched states with the finite element method. The energy level diagram of the circular crystal column superconducting structure shows that the structure has a large band gap width in both states. At the same fill factor, the circular crystal column superconducting structure has a larger band gap width than the others structures. For lattice structures, the zero transmission point of the square lattice structure is robust to the incident angle and environmental temperature. Our research has guiding significance for the design of new material photonic crystals, photon modulation and detection.

The designed defect MA ₂ Z ₄ monolayer family is highly activated toward HER electrocatalysts.

The HER electrocatalytic activity of pentagonal PdX₂ (X = S, Se) can significantly be improved by S/Se and Pd vacancies and can be further regulated by vacancy concentration.