Effect of transport agent boron triiodide on the synthesis and crystal quality of boron arsenide

Cubic boron arsenide(BAs)has attracted great attention due to its high thermal conductivity,however,its controllable,stable,and ideal preparation remains challenging.Herein,we investigated the effect of iodine-containing transport agents I_(2) and boron triiodide(BI_(3))on BAs synthesized and grown through chemical vapor transport.Results show that similar to the commonly used I_(2),BI_(3) accelerates the synthesis and improves the mass fraction of BAs from ~12% to over 90% at 820℃ and 1.5 MPa,a value beyond the promoting effect of only increasing temperature and pressure.Both agents enhance the quality of BAs crystals by reducing the full width at half maximum by up to 10%-20%.I_(2) agglomerates the grown crystals with twin defects(~50 nm wide),and BI_(3) improves the crystal anisotropy and element uniformity of BAs crystals with narrow twins(~15 nm wide)and increases the stoichiometry ratio(~0.990)to almost 1.Owing to the boron interstitials from the excessive boron supply,the spacing of layers in {111} increases to 0.286 nm in the presence of I_(2).Owing to its coordinated effect,BI_(3) only slightly influences the layer spacing at 0.275 nm,which is close to the theoretical value of 0.276 nm.In the chemical vapor transport,the anisotropic crystals with flat surfaces exhibit single-crystal characteristics under the action of BI_(3).Different from that of I_(2),the coordinated effect of BI_(3) can promote the efficient preparation of high-quality BAs crystal seeds and facilitate the advanced application of BAs.

Ultralong afterglow and unity quantum yield from a transparent CsCdCl_(3):Mn crystal

Transparent afterglow crystals are keenly desired for three-dimensional information storage.Herein,CsCdCl3 perovskite crystals were grown by a programmable cool-ing procedure in a hydrothermal reactor.The pristine crystal showed an abnormal optical behavior where the absorption increased by 2.3 folds at high temperature,leading to a fourfold boost of photoluminescence(PL)intensity.After Mn2+dop-ing,the PL quantum yield was improved to nearly unity.Importantly,the doped crystals exhibited an ultralong afterglow up to 12 h after ceasing UV excitation and a high transmittance up to 75%in the visible region.This work brought a new mem-ber to the library of transparent afterglow crystal,opening up many possibilities to advanced applications such as volumetric display and three-dimensional information encryption.

Blue LED-pumped intense short-wave infrared luminescence based on Cr^(3+)-Yb^(3+)-co-doped phosphors

The growing demand for spectroscopy applications in the areas of agriculture,retail and healthcare has led to extensive research on infrared light sources.The ability of phosphors to absorb blue light from commercial LED and convert the excitation energy into long-wavelength infrared luminescence is crucial for the design of cost-effective and high-performance phosphor-converted infrared LEDs.However,the lack of ideal blue-pumped short-wave infrared(SWIR)phosphors with an emission peak longer than 900 nm greatly limits the development of SWIR LEDs using light converter technology.Here we have developed a series of SWIR-emitting materials with high luminescence efficiency and excellent thermal stability by co-doping Cr^(3+)-Yb^(3+) ion pairs into Lu_(0.2)Sc_(0.8)BO_(3) host materials.Benefitting from strong light absorption of Cr^(3+) in the blue waveband and very efficient Cr^(3+)→Yb^(3+) energy transfer,the as-synthesized Lu_(0.2)Sc_(0.8)BO_(3):Cr^(3+),Yb^(3+) phosphor emits intense SWIR light in the 900-1200 nm from Yb^(3+) under excitation with blue light at~460 nm.The optimized phosphor presents an internal quantum yield of 73.6%and the SWIR luminescence intensity at 100℃can still keep 88.4%of the starting value at 25℃.SWIR LED prototype device based on Lu0.2Sc0.8BO3∶Cr^(3+)Yb^(3+) phosphor exhibits exceptional luminescence performance,delivering SWIR radiant power of 18.4 mW with 9.3%of blue-to-SWIR power conversion efficiency and 5.0%of electricity-to-SWIR light energy conversion efficiency at 120 mA driving current.Moreover,under the illumination of high-power SWIR LED,covert information identification and night vision lighting have been realized,demonstrating a very bright prospect for practical applications.

数据科学与化学交叉视域下的重金属危废物相分析

我国重金属危险废物(重金属危废)产生量全球第一,高达数千万吨/年,环境危害性极强,一旦控制不当将引发重大环境安全事故,其处理处置一直是环境领域的世界难题。目前,基于物相调控的资源化是解决该难题最具潜力的方案。然而,重金属危废来源广,物相种类多样、结构多变,导致难以发展共性的资源化技术。本文以《国家危险废物名录》中所列危废为研究对象,在数据科学和化学交叉视域下系统深入地分析重金属危废的物相组成特征,归纳出重金属危废中的共性物相,并构建了全行业重金属危废中重金属元素与物相的映射图谱。在此基础上,本文介绍了两种重金属赋存分布的定量分析方法,明确了典型重金属危废中的赋存物相,最后展望了重金属危废物相新认知在推动处理处置技术革新方面的广阔前景。

Coordinated Optimization of Multi-energy Generation Systems Considering the Health Damages of Coal-fired Pollutant Dispersion

Pollutants emitted from coal-fired power plants lead to the deterioration of air quality in developing countries,and contribute to both mortality and morbidity.To improve air quality from power generation,new dispatch strategies incorporated with air pollution dispersion models should be considered.This paper takes into account the impact of meteorological variations on spatio-temporal dispersion of pollutants.Depending on the coal-fired pollutant concentration estimated by the Gaussian plume dispersion model,exposure-response functions are used to quantify the resulting health effects.Furthermore,the corresponding economic costs of health damages are incorporated to penalize the power dispatch.Considering generation costs and economic costs of health damages,this paper formulates a twostage stochastic optimization model of a multi-energy generation system including coal units,gas units,and photovoltaic stations.Finally,numerical studies based on a modified IEEE 14-node system are performed for illustration and validation.

A self-assembled nanoflower-like Ni_(5)P_(4)@NiSe_(2) heterostructure with hierarchical pores triggering high-efficiency electrocatalysis for Li-O_(2) batteries

The remarkably high theoretical energy densities of Li–O_(2) batteries have triggered tremendous efforts for next-generation conversion devices.Discovering efficient oxygen reduction reaction and oxygen evolution reaction(ORR/OER)bifunctional catalysts and revealing their internal structure-property relationships are crucial in developing high-performance Li–O_(2) batteries.Herein,we have prepared a nanoflower-like Ni_(5)P_(4)@NiSe_(2) heterostructure and employed it as a cathode catalyst for Li–O_(2) batteries.As expected,the three-dimensional biphasic Ni_(5)P_(4)@NiSe_(2) nanoflowers facilitated the exposure of adequate active moieties and provide sufficient space to store more discharge products.Moreover,the strong electron redistribution between Ni_(5)P_(4) and NiSe_(2) heterojunctions could result in the built-in electric fields,thus greatly facilitating the ORR/OER kinetics.Based on the above merits,the Ni_(5)P_(4)@NiSe_(2) heterostructure catalyst improved the catalytic performance of Li–O_(2) batteries and holds great promise in realizing their practical applications as well as inspiration for the design of other catalytic materials.