Yonggang Wang

For a long time, the potential of regulating anion ordering in the first coordination shell of Eu ²⁺ to tune its luminescence properties has remained largely unexplored. In this work, exploiting the (in)compatibility of N in nitridosilicates and O in oxosilicates, we systematically achieved N/O ordering regulation in BaSi ₆ N ₈ O through coupled [AlO]‐for‐[SiN] substitution. Neutron diffraction and X‐ray diffraction data revealed ordered [AlO] substitution at Si2/N1 sites together with Ba ²⁺ vacancies and partial O substitution at N3 sites in [Al2N ₃ O] for the structure of Ba _{1‐ y} Al _x Si _{6‐ x} N _{8‐ x ‐2 y} O _{1+ x +2 y} (0.72 ≤ x ≤ 1.86, 0.05 ≤ y ≤ 0.09). Combined structural analysis and DFT calculations show that ordered substitution induces lattice stress along the Al‐N bond direction, splitting Ba coordination environments into [BaN ₂ (N/O) ₄ ] and [BaN ₆ (N/O) ₂ ]. The former causes spectral broadening, whereas the latter generates a new blue emission band, together producing single‐phase broadband cyan‐green emission. The substitution negligibly affects the intrinsic structural rigidity of the host lattice. Meanwhile, Ba ²⁺ vacancies introduce deep defect energy levels, ultimately giving rise to anti‐thermal quenching behavior. These findings establish N/O ordering regulation as an effective strategy for designing thermally robust white‐light‐emitting oxynitride phosphors.

The bulk photovoltaic effect (BPVE) in polar crystals offers a promising way to surpass the energy-conversion limits of conventional p–n junction devices. In layered materials, BPVE is typically dominated by an out-of-plane component. However, strong in-plane performance is essential for planar photovoltaics, requiring innovative strategies to overcome fundamental material constraints. In this study, an innovative pressure-induced emergence of in-plane BPVE is demonstrated in the planar-nonpolar layered bulk semiconductor γ-type indium selenide. External pressure distorts the lattice and breaks the intrinsic threefold rotational symmetry, triggering in-plane photovoltaic responses that are otherwise symmetry-forbidden at ambient pressure. Furthermore, the in-plane BPVE shows a distinctive crystallographic orientation dependence: the photocurrent is significantly higher along the armchair direction than along the zigzag direction, with a large anisotropy ratio of up to 280 observed at 0.16 GPa. Experimental characterization and first-principles calculations reveal that pressure lifts the symmetry-protected planar nonpolarity, reconstructing the electronic structure and activating a sizable in-plane shift-current response that is forbidden at ambient pressure. More broadly, this work establishes symmetry engineering through pressure as a general strategy for achieving large in-plane bulk photovoltaic responses in layered systems, without relying on material nanostructuring or interfacial design.

Adaptive thermal‐management materials capable of direction‐dependent heat transport are highly desirable for building‐envelope and other moderate‐temperature applications, yet scalable and flexible thermal rectifiers remain limited. Here, we report a polyester‐based phase‐change thermal diode meta‐fabric (TDMF) fabricated via continuous modified rotary jet spinning (M‐RJS), with potential compatibility for textile‐scale processing. The TDMF comprises a hot‐pressed reduced graphene oxide (rGO)‐integrated dense conductive layer (DCL) and an ultra‐porous fluffy insulating layer (FIL), coupling structural asymmetry with phase‐change‐induced thermal nonlinearity. An optimized configuration containing 80 wt.% phase‐change material in the DCL achieves a maximum material‐level thermal rectification ratio of ∼2.1 at Δ T = 45 K, where PCM‐assisted thermal switching becomes pronounced. The rGO‐enabled conductive network promotes forward heat transfer and PCM activation, whereas the porous FIL suppresses reverse heat transport through reduced interfacial contact and increased thermal resistance. The meta‐fabric also exhibits high flexibility and moisture permeability. A low‐temperature orientation test shows a ∼1.9°C surface‐temperature difference between opposite bilayer orientations, while building‐envelope analogue tests show differences up to ∼2.7°C under controlled irradiation. This work establishes a scalable fibrous platform for directional thermal management, particularly relevant to building‐envelope and other moderate‐temperature applications using the current PCM formulation design.

Antifluorite oxides containing ordered tetrahedral voids provide a structurally flexible platform for Li-ion transport; however, experimentally identifying and controlling the defect configurations that activate these voids remains challenging. Here, Li-excess defect engineering is demonstrated in orthorhombic Li5AlO4 to regulate its Li-ion transport behavior. High-resolution time-of-flight neutron powder diffraction (TOF-NPD), combined with Rietveld refinement and Fourier difference nuclear-density mapping, resolves the underlying Li-related defect architecture. The refinement results reveal that excess Li is accommodated through the coupled formation of Al/Li antisite occupancy at the 2a Wyckoff site and newly occupied interstitial Li at the intrinsically vacant 2b site, accompanied by systematic lattice expansion and local structural relaxation. BVSE-guided CI-NEB calculations reveal a multistep Li-ion migration network, in which the three-dimensional bottleneck decreases from 0.43 eV in pristine Li5AlO4 to 0.40 eV in the coupled-defect model, while the local migration segments directly involving the occupied 2b site exhibit larger barrier reductions. Consistently, electrochemical impedance spectroscopy shows an increase in the room-temperature bulk ionic conductivity to 3.33 × 10–7 S cm–1 for the Li-excess sample. These findings establish an experimentally validated correlation between Li-related defect chemistry and ion transport in Li5AlO4, providing guidance for defect-enabled transport design in antifluorite oxide conductors.

Barocaloric refrigeration technology offers a promising environmentally friendly alternative to conventional vapor‐compression refrigeration. In most barocaloric materials, applied pressure induces the order of the structure through volume contraction, leading to heat release. However, the inverse barocaloric effect arising from flexible long‐chain compounds, in which pressure drives disorder and heat absorption, remains rarely reported. Here, we report an inverse barocaloric effect in the layered alkylsulfonate, sodium 1‐octanesulfonate. Upon pressurization, the material absorbs heat from the surroundings, exhibiting a pressure coefficient of the transition temperature of −6.7 K kbar ⁻¹ , with an isothermal entropy change of 71.7 J kg ⁻¹ K ⁻¹ , and an adiabatic temperature change of 3–8 K under 1 kbar. Variable‐temperature XRD and Raman spectroscopy reveal the coexistence of monolayer and bilayer structures in the crystal, with pressure‐ and temperature‐driven changes in alkyl chain tilt and the formation of gauche defects that collectively increase conformational disorder. Structural analysis further identifies a negative thermal expansion along the c ‐axis upon heating, which underpins the unconventional pressure‐temperature coupling responsible for the inverse response. These findings establish flexible‐chain layered surfactants as a new and distinctive platform for barocaloric materials, offering unique inverse responses that expand the design strategies for high‐performance barocaloric refrigeration systems.

Piezocatalytic water splitting offers a sustainable route for hydrogen evolution, yet is challenged by weak polarity and slow charge separation kinetics under stress. Herein, we report strong polar hydroxylated Bi ₂ O ₂ CO ₃ (BOC) synthesized scalably, characterized by noncentrosymmetric (NCS) planar triangular [CO ₃ ] groups and surface hydroxyls, which applies as a robust piezocatalyst for hydrogen evolution. The aligned NCS planar [CO ₃ ] triangulars in BOC enable oriented accumulation of dipole moments to produce strong spontaneous polarization, and the intrinsic delocalized π ‐electrons within these structural units construct a conjugation freeway that minimizes charge migration resistance. Further external mechanical stress triggers a highly anisotropic lattice response; specifically, compression along the b ‐axis induces extreme geometric and electronic asymmetries that amplify the interlayer internal electric field (IEF) for charge separation. When synergistically coupled with surface hydroxylation, this stress‐induced structural distortion significantly lowers the work function and interfacial kinetic barrier for electron escape. Consequently, the hydroxylated BOC catalyst achieves an ultrahigh piezocatalytic H ₂ evolution rate of 3055 µmol·g ⁻¹ ·h ⁻¹ and a record mechanical‐to‐hydrogen (MTH) energy conversion efficiency of 0.31% in pure water. It also maintains robust H ₂ evolution from real‐world aquatic matrices, including rainwater, seawater, and antibiotic wastewater. This work establishes a polar group design‐oriented paradigm for exploiting advanced piezocatalysts.

Borates exhibit exceptional structural diversity, yet high-pressure/high-temperature (HP/HT) synthesis has predominantly focused on increasingly extreme conditions, leaving moderate pressure-temperature regimes largely unexplored. Here, we demonstrate that this limitation is primarily kinetic rather than thermodynamic. By integrating sol-gel-derived, chemically homogeneous precursors with HP/HT treatment, we establish a precursor-controlled strategy that enables systematic access to a chemically fertile moderate-pressure regime (≤3 GPa, ≤ 800 °C). This approach allows the synthesis of known high-pressure borates (β-SmB₃O₆, β-SnB₄O₇, δ-BiB₃O₆) under substantially milder conditions and extends the β-REB₅O₉ (RE = Pr, Nd) series. Moreover, it leads to the discovery of two new families of hydrated borates, β-REB₆O₉(OH)₃ (RE = La-Nd) and RE₆B₃₆O₅₉(OH)₈ (RE = Nd, Sm, Eu), whose structures are resolved by 3D electron diffraction and powder XRD. Both families adopt polar P6₃ symmetry and feature large 12- and 16-membered ring channel topologies within fully tetrahedral borate frameworks, an outcome that contrasts with the expected densification under compression. Temperature-dependent phase evolution further reveals that moderate HP/HT conditions can stabilize partially dehydrated, metastable frameworks inaccessible at ambient pressure. These results demonstrate that precursor-controlled kinetics can redefine accessible phase space in HP/HT synthesis, establishing moderate-pressure regimes as productive platforms for discovering structurally complex borates and beyond.

We report a MOF-derived senary high-entropy antiperovskite carbonitride delivering exceptional oxygen evolution performance (264 mV at 10 mA cm ^-2). Crucially, this conductive precatalyst undergoes in situ surface reconstruction during anodic polarization, forming an active amorphous M-OOH shell that successfully triggers the highly efficient lattice oxygen-mediated (LOM) pathway.

Lithium-rich antifluorite oxides formed by metal ion substitution in Li₂O are highly promising cathode prelithiation materials. Understanding the connection between their structure and performance is crucial for this type of material. In this paper, by forming solid solutions of α/β-Li₅AlO₄ and Li₅FeO₄, a group of continuous solid solutions, α-Li₅Fe_xAl_1-xO₄, and another group of phase transition solid solutions, β-Li₅Fe_xAl_1-xO₄, which underwent a phase transition at x = 0.5 were obtained, respectively. Changes in the local and electronic structures of the FeO₄ polyhedra were observed in the α-phase solid solution, and the decrease in electrochemical activity led to a linear attenuation of battery capacity. The structural changes after the phase transition of the β-phase solid solution led to the enhancement of the Li-Fe interaction, resulting in the disappearance of the delithiation performance within the working voltage. This study established a direct connection among local coordination structure, electronic structure, and electrochemical activity in lithium-rich antifluorite with abundant lithium content, providing a key theoretical basis for the rational design of high-performance prelithiation agents.

Anode-free lithium metal batteries (AF-LMBs) have been recognized as a promising approach for realizing highly safe and cost-effective lithium metal batteries with high energy density but suffer from low Coulombic efficiency (CE) and short cycle life. Here, we demonstrate high-energy and long-life AF-LMBs by leveraging the high-capacity and Li replenishment effect of surface-stabilized Li-rich Mn-based oxide (LRMO) cathodes. The irreversible capacity loss during LRMO formation, typically detrimental, is harnessed to release extra Li that deposits on the current collector, compensating for Li inventory loss and extending cell lifetime. Simultaneously, Li replenishment strategy during the formation cycle activates surface lattice oxygen, which reacts with hydrofluoroether cosolvents in a localized high-concentration electrolyte to enable a fluorinated cathode-electrolyte interphase and fluorination of the LRMO surface. As a result, a 2–ampere hour anode-free pouch cell retains 80% capacity after 260 cycles, and a 30–ampere hour pouch cell delivers 350 watt-hours per kilogram and 1200 watt-hours per liter with 84.4% retention after 180 cycles, alongside impressive low-temperature performance and rate capability. The demonstrated commercial viability of our AF-LMB showcases the essence of coherent cathode and electrolyte design for achieving high-energy and long-life AF-LMBs.