Fabrication of Ceramic-Polymer Piezo-Composites with Triply Periodic Minimal Interfaces via Digital Light Processing

The geometry of the phase interface in co-continuous piezoelectric composites is critical in improving their piezo-electric properties.However,conventional co-continuous piezoelectric composites are mostly simple structures such as wood stacks or honeycombs,which are prone to stress concentrations at the joints,thus reducing the fatigue service performance and force-electric conversion efficiency of piezoelectric composites.Such simple structures limit further improvements in the overall performance of co-continuous piezoelectric composites.In this study,based on the digital light processing 3D printing method,we investigated the influence of three dif-ferent structures-the gyroid,diamond,and woodpile interfaces-on the piezoelectric and mechanical properties of co-continuous ceramic/polymer piezoelectric composites.These findings demonstrate that the gyroid and di-amond interfaces outperformed the ceramic skeleton of the woodpile interface in terms of both mechanical and electrical properties.When the ceramic volume percentage was 50%,the piezo-composite of the gyroid surface exhibited the greatest hydrostatic figure of merit(HFOM),reaching 4.23×10^(−12) Pa^(−1),and its piezoelectric coeffi-cient(d_(33))and relative dielectric constant(εr)reached 115 pC/N and 748,respectively.The research results lay the foundation for the application of co-continuous piezoelectric composites in underwater communication and detection.

Significantly enhanced piezo-photocatalytic capability in BaTiO_(3) nanowires for degrading organic dye

Over the last several years,piezo-photocatalytic effect was intensively investigated for a facile,effective and promising protocol to sewage treatment and environmental remediation.The research on the integration of piezocatalytic and photocatalytic process on lead-free ferroelectric materials is highly demanded to further push this field forward.In this work,BaTiO_(3) nanowires(BT NWs)were fabricated by a two-step hydrothermal method.The degradation of organic dye(methyl orange,MO)aqueous solution(5 mg L^(-1))by integrating photocatalysis with the piezoelectric-like effect under UV light radiation and ultrasonic vibration was investigated.The decomposition ratio reaches up to ~98.17%(at 80 min),which is around 1.28 and 2.24 times of the sole piezocatalysis and photocatalysis process,respectively.The intermediate product of hydroxyl radical(·OH)and superoxide radical(·O_(2)^(-))was detected and quantified by radical trapping experiments,to illustrating their key role in degrading MO molecules.In addition,we carried out sequential cycles to evaluate the cycling stability and usage durability of catalysts and a reduction of ~15% in the efficiency was observed after four cycles.This work provides a promising paradigm for the further development of piezo-photocatalytic materials and target applications in environmental field.

Robust superamphiphobic coatings with gradient and hierarchical architecture and excellent anti-flashover performances

Biomimetic superhydrophobic(SH)coatings have emerged as a promising alternative to traditional room temperature vulcanizing(RTV)silicone rubber coatings for improving the flashover strength of insulators.However,organic contamination occurs in outdoor applications and thus a superamphiphobic(SAP)surface is more desirable but not yet reported for improving flashover performance.Herein,we developed a novel anti-flashover technique by fabricating robust SAP coating with unique gradient and micro-nanoscale hierarchical architecture.The SAP coating was fabricated by sequentially spray-depositing a resin-based primer and a silica-based topcoat on substrates(i.e.,glass slides and insulators).The primer not only functions as an adhesive offering strong adhesion to the substrate but also offers a micromastoid-like structure facilitating the subsequent formation of hierarchical micro-nanostructure.The appropriate spraying pressure leads to a diffusion of the fluorocarbon-modified silica nanoparticles into the primer to form a unique gradient structure,by analogy to inserting bullets into a wood.These features render the SAP coating excellent robustness with strong abrasive resistance,excellent ultraviolet(UV)resistance,and excellent chemical and thermal stability.Pollution flashover property of the SAP coating was explored and compared with that of SH and RTV specimens,from which a novel organic-contamination model to evaluate the flashover performance was proposed.The coated SAP glass insulator demonstrated 42.9%pollution flashover voltage improvement than RTV-coated insulator.These stated unique features reveal the convincing potential of the present SAP coatings to be applied for not only outdoor transmission line insulators for antiflashover but also other fields for self-cleaning,anti-fouling,and anti-icing.

Construction of direct Z-scheme BPQDs-modified BiOBr thin film for enhanced photocatalytic performance under visible light irradiation

Surface modification on photocatalytic thin films is long considered as an effective strategy to improve the degradation performance,which in turn helps to alleviate the worldwide environmental pollution issue.In this study,a direct Z-scheme photocatalytic system is constructed successfully by integrating black phosphorus quantum dots(BPQDs)on the surface of BiOBr thin film prepared by hydrothermal method.The optimal BPQDs/BiOBr-1 thin film presents remarkable enhanced photocatalytic activity for degrading methyl violet(MV)and tetracycline hydrochloride(TC),which is 3 and 3.65 times higher than that of pure BiOBr counterpart.The active species involved in the reaction are ^(+),·O_(2)^(-),and·OH,which determined by radical trapping experiments.The formation of direct Z-scheme photocatalytic system makes electrons assembled in the conduction band(CB)of BPQDs and holes gathered in the valence band(VB)of BiOBr,which supports the generation of h^(+) and·O_(2)^(-) and in turn accelerates the photocatalytic reaction.Besides,the improved efficiency of charge separation,enhanced visible light absorption and enlarged specific surface area also contributed to the enhanced photocatalytic performance of BPQDs/BiOBr.This work provides a feasible strategy for optimizing photocatalytic thin films via detailed analyzing the role of BPQDs in the construction of direct Z-scheme photocatalysts.

Piezoelectric ceramics with high piezoelectricity and broad temperature usage range

There is a general observation that the Curie temperature and piezoelectric property of the ferroelectric ceramics can be enhanced only at the expense of each other,i.e.,higher piezoelectricity,lower Curie temperature,thus,limits their applications over broad temperature range.In this research,Sm-modified 0.15 Pb(Mg_(1/3)Nb_(2/3))O_(3)-(0.85-x)PbZrO_(3)-xPbTiO_(3) ceramics have been studied,where excellent piezoelectric coefficients d33¼720 pC/N,d_(33)*=950 pm/V and high Curie temperature T_(C)=293℃ were simultaneously achieved for x=0.42 composition by designing the morphotropic phase boundary(MPB)with local structural heterogeneity.Of particular significance is that a high thermal stability was observed with piezoelectric variation below 20%with temperature up to 280℃,demonstrating that the x=0.42 composition is a good candidate for piezoelectric application over broad temperature range where high temperature stability is required.This work provides a good paradigm for designing highperformance piezoelectric ceramics with high thermal stability via a combination of MPB and local structural heterogeneity.