Advanced Powder Materials最新文献

Although the Ostwald ripening approach is often utilized to manufacture single hollow metal oxide, constructing hollow binary oxide heterostructures as potent photoelectrochemical (PEC) catalysts is still obscure and challenging. Herein, we reveal a general strategy for fabricating hollow binary oxides heterostructures (Co₃O₄-δ-MnO₂ and Co₃O₄–SnO₂) utilizing Ostwald ripening. Hollow Co₃O₄-δ-MnO₂ nano-network with the structure evolution process was systematically explored through experimental and theoretical tools, identifying the origin of hollow binary oxides due to the interfaces acting as landing sites for their growth. In addition, the structural evolution, from hollow Co₃O₄-δ-MnO₂ to Co₃O₄-α-MnO₂, can be observed when the time of secondary hydrothermal reaches 96 ​h due to the topotactic layer-to-tunnel transition process. Notably, optimized Co₃O₄-δ-MnO₂-48 exhibits a superior PEC degradation efficiency of 96.42% and excellent durability (20,000 ​min) under harsh acid conditions, attributed to the massive hollow structures' vast surface area for high intently active species. Furthermore, density functional theory simulations elucidated the Co₃O₄-δ-MnO₂’ electron-deficient surface and high d-band center (Co₃O₄-δ-MnO₂, -1.06; Co₃O₄-α-MnO_2, -1.49), strengthening the interaction between the catalyst's surface and active species and prolonging the lifetime of active species of •O₂⁻ and ¹O₂. This work not only demonstrates superior PEC degradation efficiency of hollow Co₃O₄-δ-MnO₂ for practical use but also lays the cornerstone for constructing hollow binary oxides heterostructures through Ostwald ripening.

Nanoprecipitation strengthening has been widely adopted as an effective way to design high-strength alloys, which generally leads to the loss of ductility. Here we unveil the unique bifunctionality of L1₂-structured nanoprecipitates in a FeCoNiAlTi-type high entropy alloy , enabling the combined increase of tensile strength and ductility. Results show that as-quenched precipitate-free matrix alloys undergo thermally-induced martensite transformation and form the body-centered cubic martensite phase with limited tensile ductility. In strong contrast, when introducing the dense coherent L1₂-type nanoprecipitates, the face-centered cubic matrix is temporarily stabilized, which in turn promotes the microbands-induced plasticity associated with stress-induced martensite transformation upon deformation. This allows us to achieve significantly improved work hardening capability and excellent plastic deformation stability at a high-strength level. These new findings reshape our understanding of the precipitation strengthening and could provide useful guidance for developing high-performance alloys by regulating the coherent nanoprecipitate and martensitic phase transformation.

Calcium bismuth niobate (CaBi₂Nb₂O₉) is regarded as one of the most potential high-temperature piezoelectric materials owing to its highest Curie point in bismuth layer-structured ferroelectrics. Nevertheless, low piezoelectric coefficient and low resistivity at high temperature considerably restrict its development as key electronic components. Herein, markedly improved piezoelectric properties and DC resistivity of CaBi₂Nb₂O₉ ceramics through Na⁺ and Sm³⁺ co-doping are reported. The nominal compositions Ca_1-2x(Na, Sm)_xBi₂Nb₂O₉ (x ​= ​0, 0.01, 0.025, and 0.05) ceramics have been prepared via the conventional solid state method. An optimum composition of Ca_0.95(Na, Sm)_0.025Bi₂Nb₂O₉ is obtained, which possesses a high Curie point of ∼949 ​°C, a piezoelectric coefficient of ∼12.8 ​pC/N, and a DC electrical resistivity at 500 ​°C of ∼4 ​× ​10⁷ ​Ω ​·cm. The improved d₃₃ is probably ascribed to the reduction in domain size and the increase in domain wall density caused by the reduced grain size. More importantly, after annealing at 900 ​°C for 2 ​h, the piezoelectric coefficient still maintains about 90% of the initial d₃₃ value, which displays a significant improvement compared to pure CaBi₂Nb₂O₉ ceramic with only 44% of the initial d₃₃ value. This work exhibits a feasible approach to simultaneously obtain high piezoelectric property and thermal stability in CaBi₂Nb₂O₉ ceramics by Na⁺/Sm³⁺ co-doping.

Advanced photovoltaics, such as ultra-flexible perovskite solar cells (UF-PSCs), which are known for their lightweight design and high power-to-mass ratio, have been a long-standing goal that we, as humans, have continuously pursued. Unlike normal PSCs fabricated on rigid substrates, producing high-efficiency UF-PSCs remains a challenge due to the difficulty in achieving full coverage and minimizing defects of metal halide perovskite (MHP) films. In this study, we utilized Al₂O₃ nanoparticles (NPs) as an inorganic surface modifier to enhance the wettability and reduce the roughness of poly-bis(4-phenyl) (2,4,6-trimethylphenyl) amine simultaneously. This approach proves essentials in fabricating UF-PSCs, enabling the deposition of uniform and dense MHP films with full coverage and fewer defects. We systematically investigated the effect of Al₂O₃ NPs on film formation, combining simulation with experiments. Our strategy not only significantly increases the power conversion efficiency (PCE) from 11.96% to 16.33%, but also promotes reproducibility by effectively addressing the short circuit issue commonly encountered in UF-PSCs. Additionally, our UF-PSCs demonstrates good mechanical stability, maintaining 98.6% and 79.0% of their initial PCEs after 10,000 bending cycles with radii of 1.0 and 0.5 ​mm, respectively.

Flexible lithium metal batteries with high capacity and power density have been regarded as the core power resources of wearable electronics. However, the main challenge lies in the limited electrochemical performance of solid-state polymer electrolytes, which hinders further practical applications. Incorporating functional inorganic additives is an effective approach to improve the performance, including increasing ionic conductivity, achieving dendrite inhibiting capability, and improving safety and stability. Herein, this review summarizes the latest developments of functional inorganic additives in composite solid-state electrolytes for flexible metal batteries with special emphasis on their mechanisms, strategies, and cutting-edge applications, in particular, the relationship between them is discussed in detail. Finally, the perspective on future research directions and the key challenges on this topic are outlooked.

Surface charge localization and inferior charge transfer efficiency seriously restrict the supply of reactive hydrogen and the reaction dynamics of CO₂ photoreduction performance of photocatalysts. Herein, chemically bonded BiVO₄/Bi₁₉Cl₃S₂₇ (BVO/BCS) S-scheme heterojunction with a strong internal electric field is designed. Experimental and density function theory calculation results confirm that the elaborated heterojunction accelerates the vectorial migration of photogenerated charges from BiVO₄ to Bi₁₉Cl₃S₂₇ via the interfacial chemical bonding interactions (i.e., Bi-O and Bi-S bonds) between Bi atoms of BVO and S atoms of BCS or Bi atoms of BCS and O atoms of BVO under light irradiation, breaking the interfacial barrier and surface charge localization of Bi₁₉Cl₃S₂₇, and further decreasing the energy of reactive hydrogen generation, CO₂ absorption and activation. The separation efficiency of photogenerated carriers is much more efficient than that counterpart individual in BVO/BCS S-scheme heterojunction system. As a result, BVO/BCS heterojunction exhibits a significantly improved continuous photocatalytic performance for CO₂ reduction and the 24 ​h CO yield reaches 678.27 ​μmol·g⁻¹. This work provides an atomic-level insight into charge transfer kinetics and CO₂ reduction mechanism in S-scheme heterojunction.

The effect of scanning strategy on the microstructure and properties of GH3536 Ni-based superalloy prepared by Laser Powder Bed Fusion was investigated, for the purpose of building high quality hydrocyclone part. The results show that the strength of Z67° (a zone with 67° hatch angle strategy) specimen is the highest among the four scanning strategies (0°, 67°, 90°and Z67°), with yield strength and tensile strength of 681 ​MPa and 837 ​MPa, respectively. Selective orientation of crystals occurs during the forming process because the longitudinal section of the specimen exhibits a high texture strength in (001). As the stretching proceeds, the plastic deformation mechanism of the specimen gradually changes from slip to twin-dominated, a substantial amount of twinning is observed in the region where the deformation of the specimen reaches 80%. The additive manufacturing simulation suite: Ansys Additive is used to simulate the stress and deformation of the part during the process, and the displacement results are consistent with the experimental phenomena. According to the simulation results, the structure design is optimized and the surface quality of the part is improved. The results show that the support of the part is more reasonable when the overhang angle is 45°.

Co-catalysts decorations provide unique opportunity in promoting the photocatalytic water splitting performance of graphite carbon nitride (g-C₃N₄) system, while mechanistic understanding of this complex catalytic network remains elusive. Here, taking the single-atom-based photocatalysts (M₁-g-C₃N₄) as an unprecedented simplified model system, we theoretically tracked the photocatalytic kinetics for a comprehensive understanding of the photocatalytic process and afforded the descriptor α_S1-T1/α_T1-S0 (ratio of the extent of S₁-T₁ and T₁-S₀ state mixing) and ΔG_H∗ (hydrogen adsorpti on free energy) for rational screening of photocatalysts. The targeted Fe₁-g-C₃N₄ yields an excellent H₂ evolution rate (ca. 3.2 ⋅mmol·g_cat⁻¹·h⁻¹ under full arc), two order of magnitude improvement relative to pristine g-C₃N₄ counterpart and also outperforms other representative 3d-transition-metal-based photocatalysts. This work presents a comprehensive understanding of the essential role of isolated atomic sites in the photocatalytic course and sheds light on the design of photocatalysts from both photophysical and photochemical aspects.

MXenes are an emerging class of new two-dimensional materials, which have been widely used in energy storage, catalysis, sensing, biology, and other fields due to their unique structure and properties. The distinct structure, low shear resistance, and easy-to-modify ability endow MXenes with particularly superior lubrication potentials. This review highlights the research status and applications of MXenes lubrication categorized into solid lubricants, lubricant additives, and reinforcement phase parts, summaries the influencing factors and lubrication mechanisms of MXenes lubrication, points out some unexplored research fields and unsettled questions, and then puts forwards possible solutions and prospects for the future research. The lubrication advances and potentials of MXenes are fully verified. Predictably, the emerging MXenes lubricants will exhibit remarkable application prospects in advanced manufacturing such as machining industries, automotive industries, micro/nano-electromechanical systems, and spacecraft components.

In this study, we performed first-principles calculations to determine the effects of four metallic solutes (Y, Zr, Mg, and Zn) on the hydrogen embrittlement (HE) of aluminum alloys with the Σ5(210) grain boundary (GB). The segregation energy, associated segregation concentration, and binding energy of these solutes were examined to identify their states. Moreover, the ability of the aforementioned solutes to inhibit or promote HE in the aforementioned alloys through GB energy, free surface energy, and adhesion was investigated. The Griffith and Rice–Wang–Scheiber models were used to determine the effect of nonequilibrium concentration on adhesion. Tensile tests were performed using the uniaxial strain loading method to determine the ultimate tensile strength and GB elongation of the considered alloys. The mechanism of HE inhibition by the four solutes was investigated by examining the charge density, Bader charge, and crystal orbital Hamiltonian population of the alloys. Finally, the calculation results of this study were validated through experiments.