SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4288-1
The high-temperature oxidation resistance of Cr2AlC MAX phase ceramics is severely compromised by rapid Al depletion and the formation of a brittle sub-surface Cr7C3 layer. This study elucidates how trace Y2O3 doping (0.25 and 0.5 wt.%) modulates the oxidation behavior of Cr2AlC at 1100 °C. The incorporation of 0.5 wt.% Y2O3 significantly suppresses the parabolic rate constant compared to undoped counterparts. This kinetic suppression is attributed to the Reactive Element Effect (REE), where Y3+ segregation at α-Al2O3 grain boundaries inhibits outward Al3+ diffusion, shifting the scale growth mechanism to inward oxygen diffusion control. Consequently, this retarded Al consumption prevents the decomposition of the Cr2AlC substrate into Cr7C3. While undoped specimens fail due to volume contraction and Kirkendall voiding associated with the Cr7C3 interlayer, specimens with the most effective doping content within the investigated range maintain a stable, atomically sharp α-Al2O3/Cr2AlC interface devoid of voids and decomposition products. The superior adhesion of this interface is attributed to three synergistic factors: the elimination of volumetric mismatch induced by phase transformation, the mechanical interlocking provided by Y-rich oxide pegs, and the intrinsically higher interfacial bonding strength of the α-Al2O3/Cr2AlC system as confirmed by DFT calculations. These findings provide a mechanistic framework for designing oxidation-resistant MAX phase ceramics via reactive element doping.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-4079-4
Utilization of ultrahigh-nickel LiNi_xCo_yMn_1-x-yO_2 (NCM) (x > 0.97) in Li-ion batteries can distinctively boost energy density through enhanced discharge capacity. However, capacity and thermal stability deteriorate as Ni content approaches the limit. Here, we propose a facile strategy by introducing high-valence tungsten (W) into ultrahigh-nickel polycrystalline LiNi_0.98Co_0.01Mn_0.01O_2 (PCNCM98). W-doped PCNCM98 (W-PCNCM98) exhibits refined, compactly stacked primary particles, whereas PCNCM98 shows equiaxial, non-uniform larger particles. The refined microstructure enhances mechanical strength: average particle hardness of W-PCNCM98 is 104 MPa, 1.5 times higher than PCNCM98 (68 MPa). This improved mechanical property suppresses lattice volume changes and relieves microcrack formation from H2–H3 phase transition. Consequently, cycling performance in pouch-type full cells is significantly enhanced, with capacity retention of 73% after 2000 cycles at 1 C and 25 °C, 54% higher than PCNCM98. Enhanced structural stability and strong electron affinity of W6+ also improve thermal stability: exothermic peak for W-PCNCM98 is postponed to 203 °C with heat generation of 1287 J g−1, versus 190 °C and 1528 J g−1 for PCNCM98. This high-valent doping strategy stabilizes ultrahigh-nickel NCM cathodes, accelerating large-scale EV applications.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3977-8
Single quantum well (single-QW) two-dimensional (2D) perovskites are poised to revolutionize optoelectronic devices owing to their superior stability and optoelectronic properties. However, solution-processed 2D perovskites typically suffer from disordered multiple-QW structures, leading to inconsistent device performance. Here, we introduce a solvent-hydrolysis-driven method to control crystallization kinetics, yielding highly ordered single-QW 2D perovskite films. Dimethylamine (DMA), generated from the hydrolysis of N,N-dimethylformamide (DMF), serves as a critical mediator, preventing cluster aggregation and ensuring a uniform colloidal distribution. This approach circumvents the formation of a heterogeneous intermediate phase, thereby promoting the formation of a homogeneous (DMA,MA)PbI3 phase, which is essential for single-QW film development. The resultant photodetector exhibits outstanding performance, with a responsivity of 1153 mA/W and a detectivity of 6.98 × 10^12 Jones, along with excellent photostability under ambient conditions. These attributes render it ideal for photoelectric imaging sensors and large-scale integration. Our findings establish a scalable, solution-processed strategy for high-performance 2D perovskite materials, opening new avenues for advanced optoelectronic applications.
SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-024-2798-5
Electrocatalytic nitrate reduction (NO3−RR) offers a dual solution for wastewater remediation and ambient ammonia synthesis, yet the competing hydrogen evolution reaction (HER) and sluggish eight-electron transfer limit Faradaic efficiency (FE) and yield. This study reports lanthanum-doped Co3O4 nanowire arrays on carbon cloth (La-Co3O4/CC) that achieve an NH3 FE of 96.36% and a yield of 537.44 μmol h−1 cm−2, markedly surpassing undoped Co3O4 (87.78%, 279.4 μmol h−1 cm−2). Density functional theory calculations reveal that La doping induces electron deficiency at Co sites, enhancing NO3− adsorption and optimizing hydrogenation energetics. A Zn–NO3− battery incorporating La-Co3O4/CC delivers a peak power density of 9.86 mW cm−2, demonstrating viable energy recovery. The catalyst maintains structural integrity over 24 h of continuous operation with negligible performance decay. This work establishes rare-earth doping as a rational strategy to overcome the intrinsic limitations of Co3O4 in nitrate electroreduction, providing a scalable pathway for decentralized ammonia production and nitrate removal.