Full Metal Species Quantification of Metal Supported Catalysts Through Massive TEM Images Recognition

For a practical high-loading single-atom catalyst,it is prone to forming diverse metal species owing to either the synthesis inhomogeneity or the reaction induced aggregation.The diversity of this metal species challenges the discerning about the contributions of specific metal species to the catalytic performance,and thus hampers the rational catalyst design.In this paper,a distinct solution of dispersion analysis based on transmission electron microscopy imaging specialized for metal-supported catalysts has been proposed in the capability of full-metal-species quantification(FMSQ)from single atoms to nanoparticles,including dispersion densities,shape geometry,and crystallographic surface exposure.This solution integrates two image-recognition algorithms including the electron microscopy-based atom recognition statistics(EMARS)for single atoms and U-Net type deep learning network for nanoparticles in different shapes.When applied to the C_(3)N_(4)-and nitrogen-doped carbon-supported catalysts,the FMSQ method successfully identifies the specific activity contributions of Au single atoms and particles in butadiene hydrogenation,which presents remarkable variation with the metal species constitution.This work demonstrates a promising value of our FMSQ strategy for identifying the activity origin of heterogeneous catalysis.

Structural and Piezoelectric Properties of Sr_(0.6)Ba_(0.4)Nb_2O_6 Micro-rods Synthesized by Molten-Salt Method

Sr0.6 Ba0.4 Nb2 O6 micro-rods are prepared by the molten-salt method with K2 SO4,KCl-K2 SO4,and KCl as fluxes.It reveals that the Sr0.6 Ba0.4 Nb2 O6 synthesized with KCl as a flux exhibits a single phase with tetragonal tungsten bronze structure.The measurement of X-ray diffraction indicates that the Sr0.6 Ba0.4 Nb2 O6 micro-rods synthesized at 1 300℃are anisotropic.The morphology of the powers is examined by transmission electron microscope.It reveals that the length-diameter ratio of Sr0.6 Ba0.4 Nb2 O6 micro-rods increases with increasing annealing temperature from 900℃to 1 300℃.At 1 300℃,the rod possesses a large length-diameter ratio of 8∶1.Moreover,the analysis of the piezoelectric properties of single micro-rods using apiezo-response force microscope indicates that the domains of the material are arranged along its radial direction.

Improvement of leaf K^(+) retention is a shared mechanism behind CeO_(2) and Mn_(3)O_(4) nanoparticles improved rapeseed salt tolerance

Salinity is a global issue limiting efficient agricultural production.Nanobiotechnology has been emerged as an effective approach to improve plant salt tolerance.However,little known is about the shared mechanisms between different nanomaterials-enabled plant salt tolerance.In this study,we found that both PNC[polyacrylic acid coated nanoceria(CeO_(2) nanoparticles)]and PMO(polyacrylic acid coated Mn_(3)O_(4) nanoparticles)nanozymes improved rapeseed salt tolerance.PNC and PMO treated rapeseed plants showed significantly fresh weight,dry weight,higher chlorophyll content,Fv/Fm,and carbon assimilation rate than control plants under salt stress.Results from confocal imaging with reactive oxygen species(ROS)fluorescent dye and histochemical staining experiments showed that the ROS over-accumulation level in PNC and PMO treated rapeseed was significantly lower than control plants under salt stress.Confocal imaging results with K+fluorescent dye showed that significantly higher cytosolic and vacu-olar K^(+) signals were observed in PNC and PMO treated rapeseed than control plants under salt stress.This is further confirmed by leaf K^(+) content data.Furthermore,we found that PNC and PMO treated rapeseed showed significantly lower cytosolic Na^(+) signals than control plants under salt stress.While,compared with significantly higher vacuolar Na^(+) signals in PNC treated plants,PMO treated rapeseed showed significantly lower vacuolar Na^(+) signals than control plants under salt stress.These results are further supported by qPCR results of genes of Na^(+) and K^(+) transport.Overall,our results suggest that besides maintaining ROS homeostasis,improvement of leaf K^(+) retention could be a shared mechanism in nano-improved plant salt tolerance.