Yang Liu

Electrochemical coreduction of CO2 and nitrate to urea offers a promising approach to carbon–nitrogen fixation but still suffers from sluggish C–N coupling and severe competition from ammonia formation. Existing studies primarily focus on intermediate adsorption and largely overlook the spin-state changes that occur during intermediate transformation and C–N coupling. Herein, we introduce a Cu-modulated spin-regulation strategy where Cu substitution subtly modulates the Fe electronic configuration of FeSe2 to generate spin-polarized Fe centers. We reveal that mixed-valence Fe species in Cu-FeSe2 induce a double-exchange-like spin polarization, which facilitated the migration of N-containing intermediates between neighboring Fe sites, thereby promoting C–N coupling. As a result, the Cu-FeSe2 catalyst achieves a urea Faradaic efficiency of 54.1%, a yield rate of 78.5 mmol h–1 g–1, and an electrochemical stability over 75 h. Supported by operando spectroscopic analyses and density functional theory (DFT) calculations, the spin-polarized Fe centers stabilize *COOH and *NH2 intermediates while suppressing over-hydrogenation to ammonia. This work highlights spin polarization as a promising strategy for constructing efficient electrocatalytic sites and enabling multi-intermediate electrocatalysis toward urea synthesis.

Low-symmetry, nonconvex nanocrystals offer access to superlattices with structural motifs that are difficult to realize from convex building blocks. Here, we show that polymer-grafted Gd2O3 nanotripods assemble into compact achiral and open chiral nanoporous superstructures. By tuning tripod aspect ratio, polymer ligand length, and ligand shell architecture, we direct phase selection among p2, pmg, pgg, and p6 wallpaper symmetries. In the p6 phase, planar chirality emerges through arm-to-arm interlocking. Direct ligand exchange generates mixed ligand shells with softer effective interactions, expanding the accessible phase space beyond that obtained by two-step ligand exchange. Coarse-grained simulations incorporating ligand-mediated attractions reproduce the experimental phase behavior and identify competition between translational entropy and polymer–polymer enthalpic interactions as a key driver of phase selection. These results establish ligand shell softness as a tunable design parameter for coupling nonconvex particle geometry to long-range order, enabling porous and chiral nanocrystal superstructures beyond dense, high-symmetry packing.

Ammonia (NH₃) synthesis via nitrate reduction offers a sustainable energy conversion and mitigates aquatic NO₃⁻ pollution, yet most catalysts require high overpotentials for appreciable NH₃ yields. Here, we report a sulfur-leaching strategy to transform Cu_1.8S/Ru heterostructures into a small CuRu-Cu₂O nanocomposite with abundant heterointerfaces, enabling strong electronic coupling between CuRu and Cu₂O particles, synergistically enhancing NO₃^– adsorption and reaction kinetics. The optimized catalyst achieves 95.4% NH₃ Faradaic efficiency at a low potential of 0.0 V versus reversible hydrogen electrode, stable over 30 cycles. Operando spectroscopy and density functional theory calculations reveal the incorporation of Ru facilitates active hydrogen generation, alleviating the energy barrier for hydrogenation steps at heterointerfaces. The catalyst demonstrates high stability in a membrane electrode assembly at 450 mA cm^–2 over 200 h and enables a Zinc-NO₃^– battery operation exceeding 50 h, offering a design model for durable, active nanocomposites in sustainable NH₃ synthesis.

Rechargeable magnesium batteries (RMBs) hold promise as next‐generation energy storage systems, owing to their high volumetric capacity, high safety, and abundance of Mg. However, their development is hindered by sluggish Mg ion (Mg ²⁺ ) diffusion and cathode instability, especially polysulfide and transition metal dissolution. While ultrathin protection layers offer distinct advantages over conventional bulk coatings, their synthesis remains a significant challenge. Herein, we wrap a sub‐monolayer MoS ₂ on Cu _1.81 S cathode, where MoS ₂ layer acts as a functional interface that regulates the local chemical environment and suppresses cathode dissolution. MoS ₂ layer also plays an activation role by facilitating Mg adsorption and reducing migration barriers, thereby accelerating storage kinetics. Benefiting from this synergistic design, Cu _1.81 S@MoS ₂ cathode exhibits enhanced cycling stability and rate performance. It delivers around 246 mAh/g after 200 cycles at 100 mA/g with a low fading rate (0.057% per cycle), maintaining around 107 mAh/g after 600 cycles at 400 mA/g with 99.1% coulombic efficiency (CE). Furthermore, with the MoS ₂ layer, the cathode shows excellent rate capability with 106 mAh/g at 1000 mA/g and full recovery at 20 mA/g. This work highlights a feasible nanostructuring strategy to stabilize conversion‐type cathodes to advance high‐performance RMBs.

Electrocatalytic nitrate reduction reaction (NO ₃ ⁻ RR) offers a sustainable route for NO ₃ ⁻ remediation and ammonia (NH ₃ ) electrosynthesis, yet selective NH ₃ formation is frequently limited by the sluggish hydrogenation of deeply reduced nitrogen intermediates, particularly under neutral conditions. Herein, inverse-spinel CoFe ₂ O ₄ containing high-spin octahedral ( O _h )-Co ²⁺ centers is developed as a spin-defined electrocatalyst for pH-universal NO ₃ ⁻ RR. The high-spin O _h -Co ²⁺ centers enable spin-matched interaction with the singly occupied N 2p-derived frontier orbital of open-shell *NH, thereby promoting spin-allowed electron transfer and lowering the key *NH → *NH ₂ hydrogenation barrier. In neutral electrolyte, CoFe ₂ O ₄ delivers an NH ₃ Faradaic efficiency (FE) of 95.1% at − 0.9 V _RHE and a remarkable NH ₃ yield rate of 2.2 mmol h ^− 1 cm ^− 2 at − 1.0 V _RHE , ranking among the best reported neutral NO ₃ ⁻ RR electrocatalysts. It maintains high NH ₃ selectivity and durability in acidic and alkaline media, with NH ₃ FEs exceeding 90% over a broad alkaline potential window and stable operation for over 200 h. In situ characterization reveals attenuated *NH accumulation and accelerated downstream hydrogenation, consistent with the proposed spin-matched pathway. These findings identify late-stage *NH hydrogenation as a spin-sensitive kinetic bottleneck and establish metal–adsorbate spin matching as a design principle for pH-universal NO ₃ ⁻ RR.

Fe ₃ GeTe ₂ has attracted considerable attention as a two‐dimensional (2D) van der Waals (vdW) magnetic material owing to its exceptional electromagnetic properties and potential for spintronic applications. However, complex thermodynamic competition among multiple metal species, together with severe kinetic barriers associated with the transformation from dense non‐vdW frameworks to vdW layered structures, has thus far prevented the solution phase synthesis, thereby severely limiting in‐depth property research and mechanistic understanding. Here we report a colloidal anion exchange strategy that enables the solution phase synthesis of Fe ₃ GeTe ₂ . By combining experiments with density functional theory (DFT) calculations, we identify an amorphous intermediate that kinetically decouples compositional evolution from structural reconstruction, thereby lowering the energy barrier and enabling a crystalline–amorphism–recrystalline phase transition. In this process, anion exchange induces symmetry breaking of the initial lattice and subsequent structural reorganization, ultimately driving the transformation from a non‐vdW framework to vdW layered structure. Moreover, this strategy is readily extended to other 2D material systems, leading to the successful synthesis of paramagnetic CuFeTe ₂ and NiTe ₂ as well as topological layered Bi ₂ Te ₃ , thereby establishing a general methodological pathway for accessing complex 2D vdW layered magnetic materials.

Fe ₃ GeTe ₂ has attracted considerable attention as a two‐dimensional (2D) van der Waals (vdW) magnetic material owing to its exceptional electromagnetic properties and potential for spintronic applications. However, complex thermodynamic competition among multiple metal species, together with severe kinetic barriers associated with the transformation from dense non‐vdW frameworks to vdW layered structures, has thus far prevented the solution phase synthesis, thereby severely limiting in‐depth property research and mechanistic understanding. Here we report a colloidal anion exchange strategy that enables the solution phase synthesis of Fe ₃ GeTe ₂ . By combining experiments with density functional theory (DFT) calculations, we identify an amorphous intermediate that kinetically decouples compositional evolution from structural reconstruction, thereby lowering the energy barrier and enabling a crystalline–amorphism–recrystalline phase transition. In this process, anion exchange induces symmetry breaking of the initial lattice and subsequent structural reorganization, ultimately driving the transformation from a non‐vdW framework to vdW layered structure. Moreover, this strategy is readily extended to other 2D material systems, leading to the successful synthesis of paramagnetic CuFeTe ₂ and NiTe ₂ as well as topological layered Bi ₂ Te ₃ , thereby establishing a general methodological pathway for accessing complex 2D vdW layered magnetic materials.

The synthesis of freestanding, room-temperature ferromagnetic two-dimensional (2D) materials from non-layered 3D lattices, where isotropic bonding resists anisotropic 2D growth, remains a fundamental challenge. Here, we address this by developing a ligand-mediated colloidal strategy to produce freestanding CuCr₂Te₄ nanosheets with controlled thickness and robust room-temperature ferromagnetism. Unlike substrate-dependent methods like chemical vapor deposition (CVD), our approach leverages facet-selective ligands to drive a Cu_1.43Te-to-CuCr₂Te₄ cation exchange pathway, enabling anisotropic growth of ultrathin nanosheets with preserved cubic close-packed order. Mechanistic studies reveal that oleyl alcohol stabilizes (111) facets during the transformation, suppressing strain and phase impurities (e.g., Cr₂Te₃) while ensuring ambient stability. Magnetic force microscopy (MFM) and magneto-optical Kerr effect (MOKE) measurements confirm a Curie temperature (T_C) above 300 K for thin nanosheets. Density functional theory (DFT) reveals that Cu doping enhances Cr-3d/Te-5p hybridization, leading to an increased spin-polarized density of states near the Fermi level, which in turn strengthens ferromagnetic exchange interactions. By decoupling synthesis from substrates and resolving growth pathways, this work establishes a scalable route to air-stable 2D magnets, advancing spintronic materials design with tunable anisotropy and thickness-dependent functionality.

Electrocatalytic nitrate reduction to ammonia (NO ₃ ⁻ RR) provides a sustainable pathway for nitrogen cycling and green ammonia (NH ₃ ) synthesis. Copper‐based catalysts have attracted considerable attention due to their appropriate d ‐band energy level. However, their performance is restricted by imbalanced reaction energetics, where excessive adsorption of key nitrogen intermediates (*NO ₂ , *NO, and *N) and insufficient active hydrogen (*H) availability lead to slow hydrogenation steps and poor selectivity. Herein, a sulfide‐template‐assisted electrochemical reconstruction strategy is developed to fabricate high‐spin Ni‐doped cuprous oxide (HS‐Ni‐Cu ₂ O) catalysts. The HS‐Ni‐Cu ₂ O achieves a Faradaic efficiency (FE) of 90.2% at −0.5 V _RHE and an NH ₃ yield rate of 2.19 mmol h ⁻¹ cm ⁻² at −0.8 V _RHE , together with remarkable stability for over 160 h at −450 mA cm ⁻² in a membrane electrode assembly (MEA). In situ spectroscopy and DFT calculations reveal that HS‐Ni ²⁺ incorporation promotes the formation of *H, accelerates *NO ₂ hydrogenation, and lowers the energy barrier of the rate‐determining step (*NO → *NOH) from 0.90 to 0.77 eV. Integrating NO ₃ ⁻ RR with anodic glycerol oxidation further reduces the cell voltage, enabling energy‐efficient operation. This work demonstrates spin‐state engineering as an effective strategy for designing efficient, durable, and scalable catalysts for sustainable NH ₃ synthesis and wastewater valorization.