Brønsted-acid sites induced photocatalytic cracking of low-polarity polyethylene plastics

Polyolefins such as polyethylene(PE)are one of the largest-scale synthetic plastics and play a key role in modern society.However,polyethylene is extremely inert to chemical recycling owing to its lack of chemical functionality and low polarity,making it one of the most challenging environmental hazards globally.Herein,we developed a phosphorylated CeO_(2)catalyst by an organophosphate precursor and featured efficient photocatalysis of low-density polyethylene(LDPE)without the acid or alkaline pre-treatment.Compared to pristine CeO_(2),the surface phosphorylation allows to introduce Brønsted acid sites,which facilitate to form carbonium ions on LDPE via protonation.In addition,the suitable band structure of the phosphorylated CeO_(2)catalyst enables efficient photoabsorption and generates reactive oxygen species,leading to the C–C bond cleavage of LDPE.As a result,the phosphorylated CeO_(2)catalyst exhibited an outstanding carbon conversion rate of>94%after 48 h of photocatalysis under 50 mW/cm^(2)of simulated sunlight,with a high CO_(2)product selectivity of>99%.Furthermore,the PE microparticles with sizes larger than 10μm released from LDPE plastic wrap were directly and completely degraded by photocatalysis within 12 h,suggesting an attractive and environmentally benign strategy of utilizing solar energy-based photocatalysis for reducing potential hazards of LDPE plastic trashes.

Effects of Yangyin Jiedu Decoction on Acute Oral Mucositis Caused by Radiation

[Objectives] The aim was to observe the clinical effect of Yangyin Jiedu Decoction for acute oral mucositis caused by radiotherapy for nasopharyngeal carcinoma( NPC). [Methods]Total 64 patients with non-keratinizing squamous cell carcinoma of nasopharynx were divided evenly and randomly into two groups,treatment group and control group. In the treatment group,the patients began to take Yangyin Jiedu Decoction one week before radiotherapy; while in the control group,the patients were treated with mixed solution of dexamethasone,lidocaine,recombinant human granulocyte colony stimulating factor and vitamin B12. From the beginning to the end of radiotherapy,the curative effect in the two groups was observed and compared. In addition,the levels of serum CRP,TGF-β1 and IL-6 were measured to detect the inflammatory response. [Results] The incidence of acute oral mucositis in the treatment group was significantly lower than that in the control group( P <0. 05). The effective rate was 96. 88% in the treatment group and 67. 74% in the control group. The levels of serum CRP,TGF-β1 and IL-6 in the treatment group were also lower than those in the control group. [Conclusions]Yangyin Jiedu Decoction has a good effect on prevention and treatment of acute radioactive oral mucositis and it is worthy of clinical application.

Efficient CO_(2) fixation with acetophenone on Ag-CeO_(2) electrocatalyst by a double activation strategy

The electrocarboxylation reaction is an attractive means to convert CO_(2) into valuable chemicals under ambient conditions,while it still suffers from low efficiency due to the high stability of CO_(2).In this work,we report a double activation strategy for simultaneously activating CO_(2) and acetophenone by silver-doped CeO_(2)(Ag-CeO_(2)) nanowires,featuring as an effective electrocatalyst for electrocarboxylation of acetophenone with CO_(2).Compared to the Ag foil,Ag nanoparticles and CeO_(2) nanowires,the Ag-CeO_(2)nanowire catalyst allowed to reduce the onset potential difference between CO_(2) and acetophenone activation,thus enabling efficient electrocarboxylation to form 2-phenyllactic acid.The Faradaic efficiency for producing 2-phenyllactic acid reached 91%at−1.8 V versus Ag/AgI.This double activation strategy of activating both CO_(2)and organic substrate molecules can benefit the catalyst design to improve activities and selectivities in upgrading CO_(2)fixation for higher-value electrocarboxylation.

Polaron mobility modulation by bandgap engineering in black phaseα-FAPbI_(3)

Lead halide hybrid perovskites(LHP)have emerged as one of the most promising photovoltaic materials for their remarkable solar energy conversion ability.The transportation of the photoinduced carriers in LHP could screen the defect recombination with the help of the large polaron formation.However,the physical insight of the relationship between the superior optical-electronic performance of perovskite and its polaron dynamics related to the electron-lattice strong coupling induced by the substitution engineering is still lack of investigation.Here,the bandgap modulated thin films ofα-FAPbI_(3)with different element substitution is investigated by the time resolved Terahertz spectroscopy.We find the polaron recombination dynamics could be prolonged in LHP with a relatively smaller bandgap,even though the formation of polaron will not be affected apparently.Intuitively,the large polaron mobility in(FAPb I_(3))0.95(MAPbI_(3))0.05thin film is~30%larger than that in(FAPb I_(3))0.85(MAPbBr_(3))0.15.The larger mobility in(FAPb I_(3))0.95(MAPb I_(3))0.05could be assigned to the slowing down of the carrier scattering time.Therefore,the physical origin of the higher carrier mobility in the(FAPb I_(3))0.95(MAPbI_(3))0.05should be related with the lattice distortion and enhanced electron–phonon coupling induced by the substitution.In addition,(FAPbI_(3))0.95(MAPbI_(3))0.05will lose fewer active carriers during the polaron cooling process than that in(FAPb I_(3))0.85(MAPbBr_(3)),indicating lower thermal dissipation in(FAPbI_(3))0.95(MAPbI_(3))0.05.Our results suggest that besides the smaller bandgap,the higher polaron mobility improved by the substitution engineering inα-FAPbI_(3)can also be an important factor for the high PCE of the black phaseα-FAPbI_(3)based solar cell devices.

相位分布管理的准二维钙钛矿薄膜在纳秒脉冲激光泵浦下实现高效放大自发发射

准二维钙钛矿表现出独特的光物理性质,这使它们成为激光技术潜在进步的优秀候选材料.高性能纳秒脉冲激光和放大自发发射(ASE)是实现连续波抽运光电泵浦激光器的关键工艺.然而,在纳秒脉冲激光泵浦下发展准二维钙钛矿ASE或激光仍然存在一些困难,包括表面缺陷浓度高、俄歇复合和能量传递效率低.本文通过无添加剂的Cs^(+)阳离子掺杂策略,可以很好地控制准二维钙钛矿膜的形貌和相分布,从而解决了低n相导致的能量传递途径不足的问题.本文通过快速的能量传递过程揭示了增益性质和载流子复合.基于此,掺杂适当比例Cs^(+)阳离子的PEA_(2)(FA_(0.7)Cs_(0.3))_(2)Pb_(3)Br_(10)钙钛矿膜的净增益系数比原始钙钛矿薄膜提高了近3倍,从而将纳秒激光激发下的放大自发发射阈值降低到1/3.研究结果表明,在准二维钙钛矿中掺杂Cs^(+)可为实现高性能激光器件的相位分布设计提供见解.

Advances in metal halide perovskite lasers: synthetic strategies, morphology control, and lasing emission

.In the past decade,lead halide perovskites have emerged as potential optoelectronic materials in the fields of light-emitting diode,solar cell,photodetector,and laser,due to their low-cost synthesis method,tunable bandgap,high quantum yield,large absorption,gain coefficient,and low trap-state densities.In this review,we present a comprehensive discussion of lead halide perovskite applications,with an emphasis on recent advances in synthetic strategies,morphology control,and lasing performance.In particular,the synthetic strategies of solution and vapor progress and the morphology control of perovskite nanocrystals are reviewed.Furthermore,we systematically discuss the latest development of perovskite laser with various fundamental performances,which are highly dependent on the dimension and size of nanocrystals.Finally,considering current challenges and perspectives on the development of lead halide perovskite nanocrystals,we provide an outlook on achieving high-quality lead perovskite lasers and expanding their practical applications.

Mode selection and high-quality upconversion lasing from perovskite CsPb2Br5 microplates

In recent years,halide perovskite nanostructures have had great advances and have opened up a bright future for micro/nanolasers.However,upconversion lasing by two-photon excitation with mode selection and high quality factor in one device is still rarely reported.Herein,two lasing modes are demonstrated in the all-inorganic perovskite CsPb2Br5 microplates with subwavelength thickness and uniform square shape.The net optical gain is quickly established in less than 1 ps and persists more than 30 ps,revealed by ultrafast transient absorption spectroscopy.The temperature-dependent low-threshold amplified spontaneous emission confirms the net gain for stimulated emission with a high characteristic temperature of 403 K,far surpassing the all-inorganic CsPbBr3 semiconductor gain media.Remarkably,upconversion lasing based on two kinds of microcavity effects,Fabry–Pérot and whispering-gallery modes,from the microplates at room temperature is successfully achieved with a low threshold operating in multi-or single-mode,respectively.Surprisingly,the quality factor(~3551)is among the best values obtained from perovskite micro/nanoplate upconversion lasers without an external cavity.Moreover,the highly stable chromaticity with color drift only less than 0.1 nm also outbalances the all-inorganic CsPbBr3 ones.These superior performances of CsPb2Br5 microplate lasing with a facile solution synthesis procedure will offer a feasible structure to fabricate specific functionalities for high-performance frequency upconversion micro/nanoscale photonic integrated devices.

Unraveling and tuning the linear correlation between CH_(4) and C_(2) production rates in CO_(2) electroreduction

Although many catalysts have been reported for the CO_(2)electroreduction to C_(1)or C_(2)chemicals,the insufficient understanding of fundamental correlations among different products still hinders the development of universal catalyst design strategies.Herein,we first discover that the surface*CO coverage is stable over a wide potential range and reveal a linear correlation between the partial current densities of CH_(4)and C_(2)products in this potential range,also supported by the theoretical kinetic analysis.Based on the mechanism that*CHO is the common intermediate in the formation of both CH_(4)(*CHO→CH4)and C_(1)(*CHO+*CO→C_(2)),we then unravel that this linear correlation is universal and the slope can be varied by tuning the surface*H or*CO coverage to promote the selectivity of CH_(4)or C_(2)products,respectively.As proofs-of-concept,using carbon-coated Cu particles,the surface*H coverage can be increased to enhance CH_(4)production,presenting a high CO_(2)-to-CH_(4)Faradaic efficiency(FE_(CH_(4))~52%)and an outstanding CH_(4)partial current density of-337 m A cm;.On the other hand,using an Agdoped Cu catalyst,the CO_(2)RR selectivity is switched to the C_(2)pathway,with a substantially promoted FE;of 79%and a high partial current density of-421 m A cm;.Our discovery of tuning intermediate coverages suggests a powerful catalyst design strategy for different CO_(2)electroreduction pathways.

Demonstration of joule-level chirped pulse amplification based on tiled Ti:sapphire amplifier

A novel tiled Ti:sapphire(Ti:S)amplifier was experimentally demonstrated with>1 J amplified chirped pulse output.Two Ti:S crystals having dimensions of 14 mm×14 mm×25 mm were tiled as the gain medium in a four-pass amplifier.Maximum output energy of 1.18 J was obtained with 2.75 J pump energy.The energy conversion efficiency of the tiled Ti:S amplifier was comparable with a single Ti:S amplifier.The laser pulse having the maximum peak power of 28 TW was obtained after the compressor.Moreover,the influence of the beam gap on the far field was discussed.This novel tiled Ti:S amplifier technique can provide a potential way for 100 PW or EW lasers in the future.

Surface ligand modified cesium lead bromide/silica sphere composites for low-threshold upconversion lasing

In recent years,all-inorganic halide perovskite quantum dots(QDs)have drawn attention as promising candidates for photodetectors,light-emitting diodes,and lasing applications.However,the sensitivity and instability of perovskite to moisture and heat seriously restrict their practical application to optoelectronic devices.Recently,a facile ligand-engineering strategy to suppress aggregation by replacing traditional long ligands oleylamine(OAm)during the hot injection process has been reported.Here,we further explore its thermal stability and the evolution of photoluminescence quantum yield(PLQY)under ambient environment.The modified CsPbBr_(3)QDs film can maintain 33%of initial PL intensity,but only 17%is retained in the case of unmodified QDs after 10 h continuous heating.Further,the obtained QDs with higher initial PLQY(91.8%)can maintain PLQY to 39.9%after being continuously exposed in air for 100 days,while the PLQY of original QDs is reduced to 5.5%.Furthermore,after adhering CsPbBr3 QDs on the surface of a micro SiO_(2)sphere,we successfully achieve the highly-efficient upconversion random laser.In comparison with the unmodified CsPbBr_(3)QDs,the laser from the modified CsPbBr_(3)QDs presents a decreased threshold of 79.81μJ/cm^(2)and higher quality factor(Q)of 1312.This work may not only provide a facile strategy to synthesize CsPbBr_(3) QDs with excellent photochemical properties but also a bright prospect for high-performance random lasers.

Tuning Structures and Microenvironments of Cu-Based Catalysts for Sustainable CO_(2) and CO Electroreduction

CONSPECTUS:The carbon balance has been disrupted by the widespread use of fossil fuels and subsequent excessive emissions of carbon dioxide(CO_(2)),which has become an increasingly critical environmental challenge for human society.The production and use of renewable energy sources and/or chemicals have been proposed as important strategies to reduce emissions,of which the electrochemical CO_(2)(or CO)reduction reaction(CO_(2)RR/CORR)in the aqueous systems represents a promising approach.Benefitted by the capacity of manufacturing high-value-added products(e.g.,ethylene,ethanol,formic acid,etc.)with a net-zero carbon emission,copper-based CO_(2)RR/CORR powered by sustainable electricity is regarded as a potential candidate for carbon neutrality.However,the diversity of selectivities in copper-based systems poses a great challenge to the research in this field and sets a great obstacle for future industrialization.To date,scientists have revealed that the electrocatalyst design and preparation play a significant role in achieving efficient and selective CO_(2)-to-chemical(or CO-to-chemical)conversion.Although substantial efforts have been dedicated to the catalyst preparation and corresponding electrosynthesis of sustainable chemicals from CO_(2)/CO so far,most of them are still derived from empirical or random searches,which are relatively inefficient and cost-intensive.Most of the mechanism studies have suggested that both intrinsic properties(such as electron states)and extrinsic environmental factors(such as surface energy)of a catalyst can significantly alter catalytic performance.Thus,these two topics are mainly discussed for copper-based catalyst developments in this Account.Here,we provided a concise and comprehensive introduction to the well-established strategies employed for the design of copperbased electrocatalysts for CO_(2)RR/CORR.We used several examples from our research group,as well as representative studies of other research groups in this field during the recent five years,with the perspectives of tuning local electron states,regulating alloy phases,modifying interfacial coverages,and adjusting other interfacial microenvironments(e.g.,molecule modification or surface energy).Finally,we employed the techno-economic assessment with a viewpoint on the future application of CO_(2)/CO electroreduction in manufacturing sustainable chemicals.Our study indicates that when carbon price is taken into account,the electrocatalytic CO_(2)-to-chemical conversion can be more market-competitive,and several potential value-added products including formate,methanol,ethylene,and ethanol can all make profits under optimal operating conditions.Moreover,a downstream module employing traditional chemical industrial processes(e.g.,thermal polymerization,catalytic hydrolysis,or condensation process)will also make the whole electrolysis system profitable in the future.These design principles,combined with the recent advances in the development of efficient copper-based electrocatalysts,may provide a low-cost and long-lasting catalytic system for a profitable industrial-scale CO_(2)RR in the future.