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Under bending deformation, size-dependent and structure-associated strain gradients can occur at the interface of a flexoelectric semiconductor (FS) PN heterojunction. Consequentially, a giant flexoelectric coupling will be induced to significantly enhance the flexoelectric effect of FS structures. To better understand the strain gradient–enhanced modulation performance and also reveal some other new phenomena, in this work, we theoretically and numerically study a beam shaped FS laminated composite subjected to pure bending loads. We first establish a one-dimensional theoretical model and then numerically explore the mechanical behaviors of the selected FS beam laminate. During analysis, structural symmetry breaking and size effect are considered by tuning the beam structural size and material parameters. We find that different from piezoelectric semiconductors whose mobile charges are driven by the piezo-potential, the mobile charges of FS composites induced by the flexo-potential are deterministically associated with strain gradients. Moreover, the strain gradients can exhibit a strong size-dependent effect and are quite sensitive to structural asymmetry and material parameters. We believe that our work can provide a new way to tune the carrier transport and electromechanical characteristics of a PN junction and thus can be useful to guide the next-generation flexotronic device designs. [ABSTRACT FROM AUTHOR]

Strain gradient with strong size dependency and structural association (geometry or microstructure) can efficiently tune the performances of semiconductors by the flexoelectric coupling effect. In this work, we studied a novel asymmetric beam-like semiconductor made by functionally graded (FG) flexoelectric materials. When being applied with pure bending loads at two ends, it can generate a relatively large inhomogeneous strain field to achieve obvious semiconducting behaviors. Unlike the analysis for piezoelectric semiconductor materials, we considered the effects of flexoelectricity and strain gradient elasticity in constitutive equations for flexoelectric semiconductor materials. Then, the complicated mutual coupling governing equations and associated boundary conditions are rederived strictly. By the Fourier series expansion and spatial integration methods, we obtained the solutions of the set of partial differential equations with non-constant coefficients. Results show that the semiconducting electromechanical coupling performances of the beam-like FG flexoelectric semiconductor depend heavily on the ratio and structural distributions of its constituent. Moreover, it is found that the inner carrier distributions and electromechanical characteristics can be significantly tuned by the strain gradient elasticity, the flexoelectricity, and the structural size. We believe this work provides a useful guideline for the practical design and manufacture of novel electromechanical semiconductor devices. [ABSTRACT FROM AUTHOR]

The Ag/h‐BN/Bi2O3 ternary composite was facilely fabricated via self‐assembly combined with in situ reduction. Characterization results showed that the as‐prepared Ag/h‐BN/Bi2O3 possessed distinct surface plasma resonance (SPR) and Mott‐Schottky heterostructure, resulting in significant enhancement of catalytic activity for RhB removal, the reaction rate constant (2.26×10−2 min−1) is 2.5 times that of h‐BN/Bi2O3 under visible‐light irradiation for 2 hours, which was mainly ascribed to the SPR and Mott‐Schottky heterostructure result in Ag/h‐BN/Bi2O3 enhanced visible‐light harvesting capacity and the effectual spatial separation of photoinduced carriers. The quenching process of reactive species indicated that h+ and ⋅O2− play dominant role in the degradation for pollutants. This work demonstrates that Ag/h‐BN/Bi2O3 is a promising stability photocatalyst for water purification. [ABSTRACT FROM AUTHOR]