Lithium–sulfur batteries (LSBs) take a leading stand in developing next-generation secondary batteries with an exceptionally high theoretical energy density. However, the insulating nature and undesirable shuttle effect still need to be solved to improve the electrochemical performance. Herein, a freestanding graphene supported N-doped Ti₃C₂T_x MXene@S cathode is successfully synthesized via a straightforward no-slurry method. Due to its unique hierarchical microstructure, the MXene-C/S ternary hybrids with high capacity can effectively adsorb polysulfides and accelerate their conversion. Cooperatively, conductive rGO can ameliorate N-MXene nanosheet' restacking, making the lamellar N-Mxene coated sulfur particles disperse uniformly. The assembled Li–S battery with a freestanding Ti₃C₂T_x@S/graphene electrode provides an initial capacity of 1342.6 mA h g⁻¹ at 0.1C and only experiences a low capacity decay rate of 0.067% per cycle after. Even at a relatively high loading amount of 5 mg cm⁻², the battery can still yield a high specific capacity of 684.9 mA h g⁻¹ at 0.2C, and a capacity retention of 89.3% after 200 cycles.

The ultrafast demagnetization dynamics of 3d and 4f spins, respectively, in FeCo and Tb of TbFeCo alloy film are studied independently by employing a dual-color time-resolved magneto-optical Kerr spectroscopy. The demagnetization dynamics of 3d and 4f spins are independently probed, respectively, by 800 and 400 nm light. Two-step demagnetization dynamics are observed for both the 3d and 4f spins under the excitation of 800 nm laser. In particular, the onset of 4f spin dynamics presents a delayed time with respect to the one of 3d spin dynamics. Those results clearly reveal a strong inter-atomic 3d–5d–4f exchange coupling which drives the first-step subpicosecond ultrafast demagnetization process of 4f spins, and a spin(4f)-lattice coupling which drives the second-step slower demagnetization process of 4f spins. A numerical calculation based on four temperature model reproduces the coupling characteristics in the demagnetization dynamics, and reveals the energy evolution dynamics among the different subsystems. These results provide a direct demonstration of strong coupling dynamics between the two spin subsystems in rare earth-transition metal alloy occurring within subpicosecond timescale, and show a new approach for ultrafast control of 4f spins via an indirect excitation.

Target signal acquisition and detection based on sonar images is a challenging task due to the complex underwater environment. In order to solve the problem that some semantic information in sonar images is lost and model detection performance is degraded due to the complex imaging environment, we proposed a more effective and robust target detection framework based on deep learning, which can make full use of the acoustic shadow information in the forward-looking sonar images to assist underwater target detection. Firstly, the weighted box fusion method is adopted to generate a fusion box by weighted fusion of prediction boxes with high confidence, so as to obtain accurate acoustic shadow boxes. Further, the acoustic shadow box is cut down to get the feature map containing the acoustic shadow information, and then the acoustic shadow feature map and the target information feature map are adaptively fused to make full use of the acoustic shadow feature information. In addition, we introduce a threshold processing module to improve the attention of the model to important feature information. Through the underwater sonar dataset provided by Pengcheng Laboratory, the proposed method improved the average accuracy by 3.14% at the IoU threshold of 0.7, which is better than the current traditional target detection model.

Developing clean and renewable ocean wave energy is a top priority and an effective way to achieve carbon neutrality. Triboelectric nanogenerators (TENGs) have emerged as promising green and clean energy-harvesting devices. To harvest low-frequency wave energy efficiently, much effort has been made on the modification of the contact surface, which leads to a higher fabrication cost. In this work, we designed a novel “Lucky-Bag” core (LBC) for spherical TENGs with a low-cost and easy fabricating process. The nanofiber/silicone hybrid porous outer layer of the LBC can switch freely from plane to surface and improve the output performance of both the plane and spherical TENGs. Several factors, such as the input frequency, direction, and resistive load, together with the thickness were systematically investigated; the unique porous soft-contact structure increased the triboelectric contact area, and the working mechanism was studied by using the COMSOL software. The experimental results showed that the peak-to-peak open-circuit voltage (V${}_{oc}$) and short-circuit current (I${}_{sc}$) could reach 580 V and 23.5 $\mathsf{\mu }$A at 1.5 Hz, even under 2D linear motion. Besides, the maximum output power of the spherical TENGs reached 9.10 mW, which can fully power electronic devices such as capacitors and LEDs under water wave triggering. These findings provide useful guidance for optimizing the performance of spherical TENGs for practical applications in harvesting water wave energy.

The second-order planar Hall effect is an easy and effective method for the effective fields of current induced spin–orbit torque (SOT) in the in-plane magnetized ferromagnetic metal and heavy metal multilayers. Here, we report a simulation on this method by using the Stoner–Wohlfarth model. For NiFe/Pt, the experimental results are well fitted by our model. As for Pt/NiFe/Pt, it is found a strong magnetic anisotropy cannot be neglected. The contribution of magnetic anisotropy to the SOT-induced effective fields is further analyzed. Our results give us a better understanding of the SOT in such multilayers.