Valeria Nicolosi

Two‐dimensional (2D) materials have gained tremendous attention for their structural diversity and versatile functionality. However, conventional synthesis and post‐synthetic modification often provide limited control over where and how structural or chemical changes occur, restricting the precise tailoring of composition, atomic configuration, and electronic structure. Topochemical engineering offers a distinct approach by directing chemical reactions at predefined sites while preserving key structural features of parent materials, thereby enabling precise and selective modulation at the atomic and molecular levels through four core strategies: conversion, termination, substitution, and transformation. Herein, we present a systematic and critical review of the latest advances in the topochemical engineering of MXenes and other representative 2D materials (TE‐2DMs). We establish the conceptual framework and classification criteria for these strategies and discuss their implementation and underlying structural regulation mechanisms. Special emphasis is placed on the structure–performance correlations of TE‐2DMs in electrochemical energy storage and conversion. We further summarize general design principles and practical guidelines for selecting and implementing appropriate topochemical strategies. Finally, we identify key challenges and emerging opportunities in this rapidly evolving field, with the aim of guiding the rational design of high‐performance 2D functional materials for next‐generation electrochemical energy technologies.

Platinum-based chalcogenides (PtX2) can be efficiently activated as electrocatalysts for water splitting through the hydrogen evolution reaction (HER). Edges in layered PtSe2 are effective in HER; however, the effect of edge interaction with conductive electrodes like graphene remains unclear. This study investigates the mechanism by which PtX2 (X = S, Se, Te) edges interact with graphene to uncover the origin of chalcogen-dependent differences in electrocatalysis through interfacial electronic coupling. Graphene flakes decorated with PtX2 nanosheets have reduced overpotential and enhanced kinetics in the HER. Interestingly, PtSe2/graphene exhibits the lowest overpotential among all samples, even though it also has the lowest electrochemically accessible surface area. First-principles calculations confirm the interfacial coupling between PtSe2 edges and graphene with pronounced charge accumulation in platinum-selenium edges. Gibbs free energy calculations show different activities for different chalcogens of PtX2/graphene, consistent with experimental results. Our findings indicate that graphene acts as an electronic regulator for PtSe2/graphene, which enhances the intrinsic catalytic activity of the platinum-selenium edge sites, making them more effective for the HER despite their lower density. This interfacial electronic coupling through conductive electrodes provides a powerful strategy for the rational design of next-generation electrocatalysts, enabling enhanced activity and selectivity in advanced electrochemical systems.

Platinum on carbon remains the proton-exchange membrane fuel cell cathode state-of-the-art catalyst; however, durability losses tied to support corrosion and Pt coarsening hinder this catalyst. This study investigates utilizing different variations of Vulcan XC-72 and Ti3C2 MXene to improve the oxygen-reduction ORR activity and stability. Material characterization results provide in-depth knowledge of the Pt, carbon, and MXene composites. X-ray photoelectron spectroscopy of the synthesized samples shows that the Ti3C2 has been oxidized, and high-resolution transmission electron microscopy further reveals that the Pt(111) fringes are present with local anatase TiO2 derived from Ti3C2 MXene, which is also confirmed by X-ray microscopy, indicating that the active support is a Ti3C2-derived TiO2/carbon support. After a U.S. Department of Energy-derived accelerated stress test (AST), the Pt/75%C+25%Ti3C2 catalyst outperforms an in-house-made Pt/C prepared by the same method. This improvement is accompanied by reduced Pt particle growth after the AST for the Pt/75%C+25%Ti3C2 when compared to the Pt/C, which is attributed to stabilization of Pt at the MXene-derived anatase surface through Pt–O–Ti bonds, consistent with interfacial anchoring, together with the greater corrosion resistance of the oxide, in a composition that retains sufficient carbon for electronic percolation and gas transport. This study is the first coupled cathode half-cell performance and potential-cycling durability testing for MXene-derived composites benchmarked against Pt/C and provides vital information on material discovery utilizing MXenes for the ORR.

MXenes (Ti ₃ C ₂ T _x ) are two‐dimensional (2D) layered nanomaterials typically processed as aligned flakes. However, their morphology can also be engineered into crumpled architectures with distinct physicochemical properties that remain largely unexplored. Here, Aerosol Jet Printing (AJP) is established as a scalable manufacturing strategy to tailor MXene flake morphology through precise control of the printing conditions. By repurposing the printer's built‐in alignment camera, a rapid monitoring method was developed to distinguish aligned and crumpled morphologies during fabrication. Systematic investigation of the printing parameters identified mass flow, nozzle size, and ink concentration as the key variables governing flake morphology, demonstrating its general applicability on other 2D materials, such as graphene and MoS ₂ . Aligned MXene films achieved electrical conductivities of up to 2672 ± 125 S cm ^{− 1} , whereas crumpled films exhibited increased roughness and hydrophilicity. The engineered morphologies were further validated across multiple applications, including neural interfaces, antimicrobial coatings, and strain sensors. Both morphologies supported excellent biocompatibility with primary neurons and human induced pluripotent stem cell‐derived neural cells, while crumpled MXenes enhanced antibacterial activity against Staphylococcus aureus and improved strain‐sensing performance. These findings highlight the importance of controlling the morphology of 2D materials during 3D printing, providing a scalable route toward multifunctional biomedical devices.

Graphite anode offers high theoretical capacity and low potassium storage potential, making it attractive for practical potassium‐ion batteries (PIBs). Ether‐based electrolytes have been widely explored in graphite anodes because of their capability in robust solid‐electrolyte interphases (SEIs) formation, yet several challenges remain, including solvent co‐intercalation and poor oxidation stability. Compared to widely studied five‐membered cyclic ethers, the six‐membered counterparts possess advantages in improving the physical properties of electrolytes and formulating weak solvating structures that are beneficial for building stable interfaces. By hybridizing two six‐membered cyclic ethers, 1,3,5‐trioxane and 1,3‐dioxane, a thin, uniform, and inorganic‐rich SEI has been constructed. Consequently, the graphite anode delivers exceptional rate capability, realizing over 230 mAh g ⁻¹ at 2 C and 150 mAh g ⁻¹ at 6 C with outstanding cycling stability. Meanwhile, the formulated electrolyte demonstrates decent stability with 3.83 V‐class Prussian blue analogue cathodes, allowing the fabrication of high‐voltage full cells. This work enriches ether‐based electrolyte chemistry for advanced PIB development.

Acidic CO ₂ reduction reaction (CO ₂ RR) enhances carbon efficiency and electrolyzer stability. Although nickel single‐atom catalysts (Ni‐SACs) effectively convert CO ₂ into CO in neutral/alkaline conditions, their performance in acid is hindered by the competing hydrogen evolution reaction (HER). Here we show that tailoring the local strain of Ni‐SACs can enhance HER suppression across a broad potential range. Density functional theory calculations indicate that Ni‐SACs with steeper local curvature reduce *COOH adsorption by 0.23 eV while increasing *H adsorption by 0.55 eV. To validate our predictions, we leveraged carbon nanotubes (CNTs) with different diameters to impose controlled local strain on Ni‐SACs. In Ar‐saturated 0.05 M H ₂ SO ₄ , Ni‐SACs on 5‐nm CNTs (Ni‐CNT5) demonstrate the lowest hydronium and water reduction current density among all types of CNT support. In a flow cell with pH 1 catholyte, Ni‐CNT5 maintains >95% CO Faradaic efficiency (FE) from −1.0 to −2.4 V, in contrast to Ni‐CNT50 with ∼70% FE(H ₂ ) at −2.4 V. Owing to its effective HER inhibition, Ni‐CNT5 achieves 80% single‐pass CO ₂ conversion efficiency and operates stably in acidic electrolyte with negligible loss in current or selectivity. Our findings expand the toolbox for SACs engineering, highlighting the critical role of local stress for controlled activity.

Amino acids serve a crucial role in the chemical and biological sciences. However, conventional biotic and chemical synthesis strategies typically require harsh conditions and suffer from low efficiency. Here we report a tandem plasma‐electrocatalytic approach for amino acid synthesis from α ‐keto acid and ambient air. Using alanine as a representative example, this integrated process begins with plasma‐discharge activation of air, which produces nitrate at a rate of 5.28 mmol h ⁻¹ . Subsequently, a bimetallic AgBi catalyst facilitates the co‑electrolysis of nitrate and pyruvic acid, yielding alanine with a Faradaic efficiency of 58% at −200 mA cm ⁻² and an overall yield of 62.6%. In this step, Bi sites drive the nitrate‐to‐hydroxylamine conversion, while the Ag‐Bi interface catalyzes the reduction of the resulting pyruvic acid oxime, which is formed spontaneously from pyruvic acid and hydroxylamine, into the final alanine product. Moreover, our tandem system can be extended to synthesize other α ‐amino acids, including aspartic acid, 2‐aminobutyric acid, glycine, and leucine, indicating its high versatility. Further techno‐economic analysis confirms the substantial market potential of this strategy.

Engineering porous MoO ₂ /In ₂ O ₃ heterostructured nanorods with abundant oxygen vacancies enables a 3.8-fold enhancement in nitrogen reduction reaction kinetics compared to bare In ₂ O ₃ , delivering high NH ₃ yield and faradaic efficiency.

Copper-graphene (Cu-Gr) composites combine graphene’s exceptional thermal conductivity with copper’s high conductivity and ductility, making them promising for thermal management applications. Hereto, for large-scale material processing, ball milling has been envisioned as suitable production approach to combine copper and graphene into a composite material system. However, the enhanced thermal conductivity has not yet been achieved in ball-milled Cu-Gr composites due to the system’s complexity and limited understanding of thermal transport mechanisms.In this study, the change in thermal conductivity of the Cu-Gr composite upon preparation of the powder feedstock via ball milling is elucidated using an effective medium approximation (EMA) thermal model. The observed decrease in thermal conductivity from 364 W/mK for pure isotropic Cu to 200 W/mK and 95 W/mK for Cu-10wt.% Gr in in-plane and through-plane directions, respectively, is analyzed using microstructure-informed EMA predictions based on graphene structure data obtained from CT scans. The model qualitatively captures the observed reduction and indicates that the reduced intrinsic thermal conductivity of defective graphene , along with a further 30 – 40 % reduction caused by high interfacial thermal resistance (Rk) of 2.3 10-7 m2K/W, are the primary factors. Furthermore, the graphene aspect ratio and orientation distribution are key factors governing thermal conductivity anisotropy. These findings are supported by multiple characterization techniques, including SEM-scale microstructure observation, Raman spectroscopy, and experimental thermal measurements, such as thermal conductivity and coefficient of thermal expansion (CTE) measurements.