Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2024122402
Carbamazepine (CBZ), a typical emerging contaminant, poses significant environmental and health risks due to its frequent detection, high toxicity, and resistance to conventional degradation. This study synthesized a composite material (PH-BC3-600) via high-temperature pyrolysis of mining waste pyrite and discarded Polygonatum kingianum dregs biochar. The composite was employed to activate peroxymonosulfate (PMS) for CBZ degradation. Results demonstrated that biochar incorporation provided pyrite with more active sites, achieving 88.19% removal of 2.5 mg·L−1 CBZ within 5 minutes, with excellent resistance to Cl−, NO3−, and humic acid. Quenching experiments confirmed the involvement of ·OH, SO4·−, 1O2, and e− in the degradation process. The biochar increased the content of highly reductive sulfur species (S2−, S2−2, Sn2−) in PH-BC3-600, facilitating the reduction of Fe(III) to Fe(II) and thereby enhancing PMS activation. Additionally, PH-BC3-600 exhibited lower iron leaching compared to traditional pyrite-based materials, overcoming a key drawback of conventional catalysts. This study highlights the promising potential of PH-BC3-600 for activating PMS in the treatment of emerging contaminants in water.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4135-3
Sodium-ion batteries (NIBs) are increasingly recognized as a promising technology for large-scale energy storage and heavy-duty electric vehicles, owing to the global abundance and cost-effectiveness of sodium resources. While gravimetric energy density has been the focus of battery research, the burgeoning demand for compact energy storage in space-constrained applications has shifted priorities toward volumetric energy density. In this context, alloy-based anodes—particularly metallic tin (Sn)—offer a compelling theoretical capacity (847 mAh g−1) and a high tap density that far exceeds that of conventional hard carbon. However, the commercialization of micrometre-sized Sn has been chronically hindered by two intrinsic material limitations: the “cold welding” effect during manufacturing, caused by its extreme Mohs softness (1.5), leading to agglomeration of the electrode material, and the rapid structural pulverization resulting from massive volume expansion (~420%) during sodiation/desodiation cycles, causing the electrode particles to lose electrochemical activity and resulting in capacity fading. Conventional mitigation strategies, such as nanostructuring and addition of high weight-percentage carbon additives, often sacrifice initial Coulombic efficiency (ICE), volumetric capacity, and material scalability. Addressing the fundamental challenge of how to maintain stable electrical connectivity and structural integrity in micrometre-scale alloy particles without compromising the energy density of the entire electrode represents a significant research endeavor. Recently, Hu’s group introduced single-walled carbon nanotubes (SWCNTs) as a conductive cross-linker, termed “9226-SWCNT”, configured as (92 wt% Sn, 2 wt% SWCNTs, and 6 wt% carboxymethyl cellulose (CMC) binder). This specific ratio creates a robust three-dimensional cross-linked network. Unlike zero-dimensional carbon black (acetylene black), the high-aspect-ratio SWCNTs act as a flexible “nano-bandage” that wraps around the micrometre-scale Sn particles. This transforms the electrical connectivity from inefficient point contact to stable “face-to-face” contact. This network offers a dual benefit: the SWCNTs serve as a mechanical barrier that prevents Sn particles from cold welding during the mixing process, and they function as an elastic scaffold that maintains electrical continuity despite the drastic volume fluctuations of the Sn particles. When the conventional acetylene black-based electrodes fail rapidly, the 9226-SWCNT system demonstrates 87.6% capacity retention after 6000 cycles at 2 A g−1, proving that the mechanical architecture of the conductive network is as vital as its electronic properties. The Sn electrode transforms into a three-dimensional porous coral-like structure upon sodiation, which facilitates Na+ diffusion and buffers the mechanical stress induced by volume expansion. The authors compared the effects of different proportions of SWCNTs. To characterize the resulting morphological evolution, they introduced topological analysis and machine learning (ML), using the first Betti number (β1) as a metric to quantify the coral-like structure by counting the closed loops within the sodiated Sn anode. The 9226-SWCNT electrode maintains a significantly higher β1 value during cycling compared to the 9046-SWCNT (4 wt% SWCNT) sample. This reveals that a higher content of conductive additive (4% vs. 2%) actually results in fewer structural pores; that is, an excessive amount of SWCNTs hinders the topological evolution of Sn and consequently impedes its sodiation process. The authors further explain this through the “exposure effect”: initially, Sn particles are “embedded” and shielded by the SWCNT-CMC network. If the network is too dense, it restricts the necessary morphological transformation, underscoring the critical balance between conductive additive content and electrochemical performance.