Surface defect and lattice engineering of Bi_(5)O_(7)Br ultrathin nanosheets for efficient photocatalysis

The effective separation and migration of photogenerated charge carriers in bulk and on the surface of photocatalysts will significantly promote photocatalytic efficiency.However,the synchronous regulation of photocharges on both counts is challenging.Herein,the simultaneous separation of bulk and surface photocharges is conducted to enhance photocatalytic activity by coupling the surface defects and lattice engineering of bismuth oxybromide.The depth-modulated Bi_(5)O_(7)Br ultrathin nanosheets with an abundance of bismuth in the crystal structure increased the internal electric field,which propelled the separation and migration of photocharges from bulk to the surface.Creation of oxygen vacancies(OVs)on the nanosheet surface forms local electric fields,which can stimulate the migration of charges to active sites on the catalyst surface.Therefore,the OV-assembled Bi_(5)O_(7)Br nanosheets demonstrated enhanced photocatalytic degradation efficiency under simulated solar-light illumination.This study proved the possibility of charge governing via electric field modulation based on an integrated strategy.

Enhancing energy storage efficiency in lead-free dielectric ceramics through relaxor and lattice strain engineering

Dielectric capacitors with high power density and fast charge-discharge speed play an essential role in the development of pulsed power systems.The increased demands for miniaturization and practicality of pulsed power equipment also necessitate the development of dielectric materials that possess high energy density while maintaining ultrahigh efficiency(η).In particular,ultrahigh efficiency signifies minimal energy loss,which is essential for practical applications but challenging to effectively mitigate.Here,we demonstrate a strategy of incorporating heterovalent elements into Ba(Zr_(0.1)Ti_(0.9))O_(3),which contributes to achieving relaxor ferroelectric ceramics and reducing lattice strain,thereby improving the comprehensive energy storage performance.Finally,optimal energy storage performance is attained in 0.85Ba(Zr_(0.1)Ti_(0.9))O_(3)-0.15Bi(Zn_(2/3)Ta_(1/3))O_(3)(BZT-0.15BiZnTa),with an ultrahighηof 97.37%at 440 kV/cm(an advanced level in the lead-free ceramics)and an excellent recoverable energy storage density(Wrec)of 3.74 J/cm^(3).Notably,the BZT-0.15BiZnTa ceramics also exhibit exceptional temperature stability,maintaining fluctuations in Wrec within∼10%andηconsistently exceeding 90% across the wide temperature range of−55℃ to 160℃,and under a high electric field of 250 kV/cm.All these features demonstrate that the relaxor and lattice strain engineering strategies have been successful in achieving high-performance lead-free ceramics,paving the way for designing high-efficiency dielectric capacitors with a wide temperature range.

Energy storage performances regulated by BiMnO3 proportion in limited solid solution films

Na0.5Bi0.5TiO3-BiMnO3(NBT-BM)limited solid solution films were fabricated to investigate the lattice modification on the energy storage performances.The introduction of the BM solute lattice induces the NBT solvent lattices undergoing the transition from the pure phase,solid solution,solubility limit to precipitation.Correspondingly,the polarization states transfer from the macroscopic ferroelectric domains to nanodomains then to compound ferroelectric domains.The introduction of BiMnO3 generates great lattice changes including the local lattice fluctuation and the large lattice stretching,which enhance the energy storage performances,with the energy storage efficiency being enhanced from 39.2%to 53.2%and 51.7%and the energy density being enhanced from 33.1 J/cm3 to 76.5 J/cm^3 and 83.8 J/cm^3 for the BM components of 2%and 4%,respectively.The lattice modifications play a key role in the energy storage performances for limited solid solution films,which provides an alternative strategy for energy storage material.

Engineering lattice defects in 2D nanomaterials for enhancing biomedical performances

2D nanomaterials are widely investigated for biomedical applications,attributed to their large specific surface area,high therapeutic loading capacity,and unique optical,thermal,and/or electronic characteristics.Lattice defects affect the theranostic performance of 2D nanomaterials significantly by altering their electronic properties and chemical binding.Recent investigations have shown that defect-rich 2D nanomaterials are capable of enhancing tumor treatment through efficient drug delivery,photothermal and photodynamic therapies(PTT and PDT),and improving diagnostics via computed tomography(CT),photoacoustic and magnetic resonance imaging.This review summarizes recent progresses,including synthesis,characterization approach,and applications of defect-engineered 2D nanomaterials that are potentially useful in cancer treatment.The expert opinions are also proposed as the conclusion.

Dependence of corrosion resistance on grain boundary characteristics in a high nitrogen CrMn austenitic stainless steel

Processing schedules for grain boundary engineering involving different types of cold deformation（tension, compression, and rolling） and annealing were designed and carried out for 18Mn18Cr0.6N high nitrogen austenitic stainless steel. The grain boundary characteristic distribution was obtained and characterized by electron backscatter diffraction（EBSD） analysis. The corrosion resistance of the specimens with different grain boundary characteristic distribution was examined by using potentiodynamic polarization test. The corrosion behavior of different types of boundaries after sensitization was also studied.The fraction of low-∑ boundaries decreased with increasing strain, and it was insensitive to the type of cold deformation when the engineering strain was lower than 20%. At the strain of 30%, the largest and smallest fractions of low-∑ boundaries were achieved in cold-tensioned and rolled specimens, respectively. The fraction of low-∑ boundaries increased exponentially with the increase of grain size. The proportion of low-∑ angle grain boundaries increased with decreasing grain size. Increasing the fraction of low-∑ boundaries could improve the pitting corrosion resistance for the steels with the same grain size.After sensitization, the relative corrosion resistances of low-∑ angle grain boundaries, ∑3 boundaries, and ∑9 boundaries were 100%, 95%, and 25%, respectively, while ∑27 boundaries, other low-∑ boundaries and random high-angle grain boundaries had no resistance to corrosion.