Mesoporous amorphous FeOOH-encapsulated BiO_(2–x) photocatalyst with harnessing broad spectrum toward activation of persulfate for tetracycline degradation

With the growing concern about the water environment,the advanced oxidation process of persulfate activation assisted by photocatalysis has attracted considerable attention to decompose dissolved organic micropollutants.In this work,to overcome the drawbacks of the photocatalytic activity reduction caused by the photo-corrosion of non-stoichiometric BiO_(2–x),a novel material with amorphous FeOOH in situ grown on layered BiO_(2–x) to form a core-shell structure similar to popcorn chicken-like morphology was produced in two simple and environmentally beneficial steps.Through a series of degradation activity tests of hybrid materials under different conditions,the as-prepared materials exhibited remarkable degradation activity and stability toward tetracycline in the FeOOH@BiO_(2–x)/Vis/PS system due to the synergism of photocatalysis and persulfate activation.The results of XRD,SEM,TEM,XPS,FTIR,and BET show that the loading of FeOOH increases the specific surface area and active sites appreciably;the heterogeneous structure formed by FeOOH and BiO_(2–x) is more favorable to the effective separation of photogenerated carriers.The optimal degradation conditions were at a catalyst addition of 0.7 g·L^(–1),a persulfate concentration of 1.0 g·L^(–1),and an initial pH of 4.5,at which the degradation rate could reach 94.7%after 90 min.The influence of typical inorganic anions on degradation was also examined.ESR studies and radical quenching experiments revealed that·OH,SO_(4)^(-)·,and·O_(2)^(-)were the principal active species generated during the degradation of tetracycline.The results of the 1,10-phenanthroline approach proved that the effect of dissolved iron ions on the tetracycline degradation was limited,and the interfacial reaction that occurs on the active sites on the material's surface was a critical factor.This work provides a novel method for producing efficient broad-spectrum Bismuth-based composite photocatalysts and photocatalytic-activated persulfate synergistic degradation of tetracycline.

A review on electrocatalytic CO_(2) conversion via C-C and C-N coupling

Electrochemical C-C and C-N coupling reactions with the conversion of abundant and inexpensive small molecules,such as CO_(2) and nitrogencontaining species,are considered a promising route for increasing the value of CO_(2) reduction products.The development of high-performance catalysts is the key to the both electrocatalytic reactions.In this review,we present a systematic summary of the reaction systems for electrocatalytic CO_(2) reduction,along with the coupling mechanisms of C-C and C-N bonds over outstanding electrocatalytic materials recently developed.The key intermediate species and reaction pathways related to the coupling as well as the catalyst-structure relationship will be also discussed,aiming to provide insights and guidance for designing efficient CO_(2) reduction systems.

Construction of a Cu@hollow TS-1 nanoreactor based on a hierarchical full-spectrum solar light utilization strategy for photothermal synergistic artificial photosynthesis

The artificial photosynthesis technology has been recognized as a promising solution for CO_(2) utilization.Photothermal catalysis has been proposed as a novel strategy to promote the efficiency of artificial photosynthesis by coupling both photochemistry and thermochemistry.However,strategies for maximizing the use of solar spectra with different frequencies in photothermal catalysis are urgently needed.Here,a hierarchical full-spectrum solar light utilization strategy is proposed.Based on this strategy,a Cu@hollow titanium silicalite-1 zeolite(TS-1)nanoreactor with spatially separated photo/thermal catalytic sites is designed to realize high-efficiency photothermal catalytic artificial photosynthesis.The space-time yield of alcohol products over the optimal catalyst reached 64.4μmol g−1 h−1,with the selectivity of CH3CH2OH of 69.5%.This rationally designed hierarchical utilization strategy for solar light can be summarized as follows:(1)high-energy ultraviolet light is utilized to drive the initial and difficult CO_(2) activation step on the TS-1 shell;(2)visible light can induce the localized surface plasmon resonance effect on plasmonic Cu to generate hot electrons for H2O dissociation and subsequent reaction steps;and(3)low-energy near-infrared light is converted into heat by the simulated greenhouse effect by cavities to accelerate the carrier dynamics.This work provides some scientific and experimental bases for research on novel,highly efficient photothermal catalysts for artificial photosynthesis.

Loading CuO on the surface of MgO with low-coordination basic O^(2-)sites for effective enhanced CO_(2) capture and photothermal synergistic catalytic reduction of CO_(2) to ethanol

The higher capacity of CO_(2)adsorption on the surface of magnesium oxide(MgO)with low-coordination O^(2-)sites would effectively enhance the catalytic reduction of CO_(2).Herein,a series of copper oxide(CuO)and MgO composites with different mass ratios have been prepared by hydrothermal method and used for photothermal synergistic catalytic reduction of CO_(2)to ethanol.The catalyst with CuO mass ratio of 1.6% shows the best yield(15.17μmol·g^(-1)·h^(-1))under 3 h Xenon lamp illumination.The improved performance is attributable to the loose nano-sheet structure,uniform dispersion of active sites,the increased specific surface area,medium-strength basicity,the high separation efficiency of electrons and holes,and the formation of Mg-O-Cu species.The synthesized CuO and MgO composites with loose nano-sheet structure facilitate the diffusion of reactants CO_(2),so an excellent CO_(2)adsorption performance can be obtained.Meanwhile,the introduction of CuO in the form of bivalence provides higher specific surface area and porosity,thus obtaining more active sites.More importantly,the Mg-O-Cu species make the donation of electrons from MgO to CO_(2)easier,resulting in the breaking of the old Mg-O bond and the formation of C-O bond,thus promoting the adsorption and conversion of CO_(2)to ethanol.

联邦异质性优化的在线区间估计

从统计的角度来看,在联邦学习中进行统计推断来了解数据分布是至关重要的。由于本地迭代次数和本地数据集的异质性,传统的统计推断方法不适用于联邦学习。本文研究了如何构造联邦异质性优化问题的置信区间。我们引入了重调整联邦平均估计,并证明了估计的相合性。针对置信区间估计,我们证明了算法产生的参数估计的渐近正态性,并表明渐近协方差大小与终端参与率成反比。提出了一种基于重调整联邦平均的分离plug-in的在线置信区间估计方法。该方法可以在各个客户端的局部迭代次数不同的情况下在线构建有效的置信区间。由于客户端和本地数据集所存在差异,本地迭代次数的异质性是普遍存在的。因此,联邦异质性优化问题的置信区间估计具有重要意义。

Strong Consistency of Kernel Regression Estimate

In this paper, regression function estimation from independent and identically distributed data is considered. We establish strong pointwise consistency of the famous Nadaraya-Watson estimator under weaker conditions which permit to apply kernels with unbounded support and even not integrable ones and provide a general approach for constructing strongly consistent kernel estimates of regression functions.

A New Classifier for Imbalanced Data Based on a Generalized Density Ratio Model

Achieving higher true positive rate when decreasing false positive rate is always a great challenge to the imbalance learning community.This work combines penalized empirical likelihood method,lower bound algorithm and Nyströmmethod and applies these techniques along with kernel method to density ratio model.The resulting classifier,density ratio classifier(DRC),is a combination of kernelization,regularization,efficient implementation and threshold moving,all of which are critical to enable DRC to be an effective and powerful method for solving difficult imbalance problems.Compared with other methods,DRC is competitive in that it is widely applicable and it is simple and easy to use without additional imbalance handling skills.In addition,the convergence rate of the estimate of log density ratio is discussed as well.And the results of numerical analysis also show that DRC outperforms other methods in AUC and G-mean score.

Enhancing electrical conductivity of single-atom doped Co_(3)O_(4) nanosheet arrays at grain boundary by phosphor doping strategy for efficient water splitting

High electrical conductivity guarantees a rapid electron transfer and thus plays an important role in electrocatalysis.In particular,for the single atom catalysts(SACs),to facilitate interaction between the single atom and supports,precisely engineering the conductivity represents a promising strategy to design SACs with high electrochemical efficiency.Here we show rhodium(Rh)SAC anchored on Co_(3)O_(4) nanosheets arrays on nickel foam(NF),which is modified by a facile phosphorus(P-doped Rh SACCo_(3)O_(4)/NF),possessing an appropriate electronic structure and high conductivity for electrocatalytic reaction.With the introduction of P atom in the lattice,the electrocatalyst demonstrates outstanding alkaline oxygen evolution reaction(OER)activity with 50 mA·cm^(−2) under overpotential of 268 mV,6 times higher than that of Ir/C/NF.More interestingly,the P-doped Rh SAC-Co_(3)O_(4)/NF can get 50 mA·cm^(−2) at only 1.77 V for overall water splitting.Both electrical conductivity studies and density functional theory(DFT)calculations reveal that the high conductivity at grain boundary improves the charge transfer efficiency of the Rh catalytic center.Furthermore,other noble-metal(Ir,Pd,and Ru)doped Co_(3)O_(4) nanosheets arrays are prepared to exhibit the general efficacy of the phosphorus doping strategy.

Probability density estimation with surrogate data and validation sample

The probability density estimation problem with surrogate data and validation sample is considered. A regression calibration kernel density estimator is defined to incorporate the information contained in both surrogate variates and validation sample. Also, we define two weighted estimators which have less asymptotic variances but have bigger biases than the regression calibration kernel density estimator. All the proposed estimators are proved to be asymptotically normal. And the asymptotic representations for the mean squared error and mean integrated square error of the proposed estimators are established, respectively. A simulation study is conducted to compare the finite sample behaviors of the proposed estimators.