The heteroatom doping is considered a promising strategy for enhancing the performance of the MnO₂-based electrode materials for zinc-ion battery (ZIB). However, quickly discovering the high-performance doped-MnO₂ remains significant challenge to simultaneously give consideration to both the various metal types, doping concentration, and the essential screening mechanism. Herein, a novel research paradigm is developed by combining machine learning predictions with systematic experiments and theoretical calculations for solving this issue. The results simulated by machine learning from the two-dimensional perspective reveal that only when Co species are introduced into δ-MnO₂ can zinc ions (Zn²⁺) maintain the smaller binding energy gradient distribution and larger activation area ratio among the constructed various doping system database, further achieving qualitative “structure–activity” descriptor. Moreover, the density functional theory (DFT) calculations systematically unveil optimal adsorption energy/Gibbs free energy, higher negative integral crystal orbital Hamilton population (−ICOHP) (0.0125 Ha), and lower Zn²⁺ diffusion barrier (0.978 eV) for moderate Co-doped δ-MnO₂ with oxygen vacancy (Co_(M)-δ-MnO_2−x, where (M) denotes moderate Co-doping concentration) compared with the other samples, which can preserve the Zn²⁺ adsorption/desorption equilibrium and the structure integration, and accelerate the reaction kinetics. Benefiting from these advantages, the obtained ZIB using the optimized cathode can present the large specific capacity of 655.7 mAh·g⁻¹ at 0.5 A·g⁻¹ and high rate capability (209.8 mAh·g⁻¹ at 20 A·g⁻¹), which is far higher than those of the other compound cathode materials. This study offers new insights for the design and optimization of doped-δ-MnO₂ cathodes in ZIBs, and the obtained universal theoretical guidance is also suitable for constructing other high-performance layered electrode materials.

The regulation of pore structures plays a crucial role in optimizing the electromagnetic wave absorption performance of porous materials by facilitating multiple reflection/scattering effects and improving impedance matching. Among lightweight absorbers, morphable biomass-derived porous carbon has emerged as a research hotspot due to its shape-tunable morphology, adjustable porosity, low density, cost-effectiveness, and facile fabrication. In this study, tofu was employed as a precursor to prepare sponge-like tofu and porous carbon (PCM) with varying pore sizes and densities by controlling compression pressure. The results demonstrate that moderate compression pressure induces an optimized pore architecture, which effectively enhances conductive loss, polarization loss, and synergistic multiple reflection/scattering mechanisms. The optimized PCM-4K sample achieves a minimum reflection loss (RL_min) of −41.14 dB at a matching thickness of 1.3 mm, along with the broadest effective absorption bandwidth (EAB) of 4.08 GHz at 1.4 mm. This work not only presents a novel biomass-derived carbon synthesis strategy for precise pore structure engineering but also elucidates the porous-structure-mediated absorption mechanism, providing valuable insights for the design and optimization of next-generation lightweight electromagnetic wave absorbers.

Transition metal compounds (TMCs) with high theoretical capacity have been considered as promising battery-type electrode materials for hybrid supercapacitors (HSCs), yet they often encounter low rate capability and poor cycling performance. Herein, the NiCoSe₂ nanoparticles strongly bonded on the N-doped SiC nanowires (N-S@b-NCS) with Ni/Co–N bonds in their interfaces are firstly constructed via an electrodeposition method. Theoretical calculations indicate that the unique interfacial chemical bonding with built-in electric field can not only significantly facilitate charge transfer and reduce the ion diffusion barrier, but also effectively guarantee structure integration induced by the timely release of stress concentration. Benefiting from the advantages, the achieved N-S@b-NCS exhibits high specific capacity of 254.4 mAh·g⁻¹ at 1 A·g⁻¹ and still retains 183.2 mAh·g⁻¹ even at 100 A·g⁻¹, as well as outstanding cycling stability with ~ 90% capacity retention after 30,000 cycles. Additionally, a hybrid supercapacitor assembled by the obtained N-S@b-NCS displays a high energy density of 71.4 Wh·kg⁻¹ at 16 kW·kg⁻¹ and excellent durability. This work provides a creative strategy for how to construct the bonded interface with ions diffusion highway and long-term cycling stability, which can greatly push the large-scale applications of the TMCs.

Defect engineering acts as an efficiency method to modulate the microstructure and electronic structure of cathode for rechargeable magnesium batteries (RMBs). Owing to rich sulfur (S) vacancies tunes the electronic structure of VS₄ with rich S vacancies (V_S-VS₄), the lower oxidation state of V³⁺ is induced for achieving the V³⁺/V⁴⁺ and V⁴⁺/V⁵⁺ multi-electrons reaction for Mg²⁺ storage. Amorphous structure is also constructed in V_S-VS₄ by chemical vapor deposition (CVD) method under the high temperature for providing fast magnesium ions (Mg²⁺) diffusion channels and expanding inner stress release space to balance the structural stability of multi-electrons reaction process. The simple defect engineering realizes the stable multi-electrons reaction in V_S-VS₄ for enhancing its Mg²⁺ storage performance with higher specific capacity (158.6 mAh·g⁻¹ at 50 mA·g⁻¹), stable cycling performance (capacity retention ratio of 72.7% after 3600 cycles) and the superior rate capability. This work provides electrode designing guidance for achieving stable multi-electrons to fully utilize the bivalent property of multivalence metal batteries.

Carbon-based electromagnetic wave absorbing materials (absorbers) adhered with metallic sulfide nanoparticles of good electrical conductivity attract increasing researchers’ attention. In this study, on the basis of carbon fiber (C_f)@Fe₃O₄ nanocomposites obtained by the electrostatic spinning and reflow method, C_f@FeS₂ nanocomposite was successfully prepared during a further hydrothermal process. The products exhibit excellent electromagnetic wave absorption performances with a minimum reflection loss (RL_min) of −54.11 dB at 2.13 mm matching thickness. At the same time, the optimal effective absorption bandwidth (EAB) value of 6.04 GHz at a thickness of 1.98 mm covers the whole Ku band, suggesting its excellent electromagnetic wave absorption performances. In addition, the interlaced network structure constructed by carbon fiber, outstanding conductivity of FeS₂ nanoparticles, and interfacial polarization from hetero-structure play significant parts in enhancing the electromagnetic parameters and absorption performances. All these results suggest that the C_f@FeS₂ nanocomposites can be taken as a new electromagnetic wave-absorbing material under their low density, simple craft, and strong absorption characteristics.

In the last decade, electromagnetic pollution has caused people’s considerable attention. Developing absorbing material with low cost, lightweight, simple preparation, and high electromagnetic attenuation efficiency has become a feasible means to deal with this problem. In this work, core–shell SiC_NWs@MnO₂@PPy (NWs: nanowires, PPy: polypyrrole) heterostructures composed of SiC nanowires core, MnO₂ nanosheets inter-layer, and PPy coating were successfully prepared through chemical vapor deposition and two-step electrodeposition process. Taking advantage of the interfacial polarization and dipole polarization, the obtained product displays excellent electromagnetic wave absorption performances with the minimum reflection loss (RL_min) of −50.59 dB when the matching thickness is 2.41 mm, and the optimal effective absorption bandwidth (EAB) value reaches to 6.64 GHz at a matching thickness of 2.46 mm, revealing that the SiC_NWs@MnO₂@PPy nanocomposite could be served as a promising electromagnetic wave absorbing material. On the basis of systematic analysis concerning the electromagnetic parameters, the dissipation process of the incident electromagnetic wave was demonstrated reasonably, which may provide a referable preparation strategy for novel heterostructures, especially nonmagnetic lightweight absorbing material.

Development of a general regulatory strategy for efficient overall water splitting remains a challenging task. Herein, a simple, cost-fairness, and general fluorination strategy is developed to realize surface reconstruction, heteroatom doping, and vacancies engineering over cobalt phosphide (CoP) for acquiring high-performance bifunctional electrocatalysts. Specifically, the surface of CoP nanoarrays (NAs) becomes rougher, meanwhile F doped into CoP lattice and creating amounts of P vacancies by fluorination, which caused the increase of active sites and regulation of charge distribution, resulting the excellent electrocatalyst performance of F-CoP NAs/copper foam (CF). The optimized F-CoP NAs/CF delivers a lower overpotential of only 35 mV at 10 mA·cm⁻² for hydrogen evolution reaction (HER) and 231 mV at 50 mA·cm⁻² for oxygen evolution reaction (OER), and the corresponding overall water splitting requires only 1.48 V cell voltage at 10 mA·cm⁻², which are superior to the most state-of-the-art reported electrocatalysts. This work provides an innovative and feasible strategy to construct efficient electrocatalysts.

Cobalt phosphide (CoP) is considered to be a potential candidate in the field of electrocatalysis due to its low-cost, abundant resources and high electrochemical stability. However, there is a great space for further improvement of its electrocatalytic performance since its charge transfer rate and catalytic activity have not reached a satisfactory level. Herein, we design and fabricate a three dimensional urchins like V-doped CoP with different amounts of V-doping on nickel foam electrode. The V-doped CoP/NF electrode with optimized amounts of V-doping (10%) exhibits outstanding hydrogen evolution reaction (HER) performance under universal-pH conditions and preeminent oxygen evolution reaction (OER) performance in alkaline media. Notably, the assembled water-splitting cell displays a cell voltage of only 1.53 V at 10 mA·cm^-2 and has excellent durability, much better than many reported related bifunctional catalysts. The experiment results and theoretical analysis revealed that vanadium atoms replace cobalt atoms in CoP lattice. Vanadium doping can not only raise the density of electronic states near the Fermi level enhancing the conductivity of the catalyst, but can also optimize the free energy of hydrogen and oxygen-containing intermediates adsorption over CoP, thus promoting its catalytic activity. Moreover, the unique nanostructure of the catalyst provides the various shortened channels for charge transfer and reactant/electrolyte diffusion, which accelerates the electrocatalytic process. Also, the in situ growth strategy can improve the conductivity and stability of the catalyst.