Assembly mechanisms and energy transfer pathways deciphered in the cryo-EM structure of spinach photosystem Ⅱ-LHCⅡ supercomplex

Funded by the National Natural Science Foundation of China(NSFC),Ministry of Science and Technology of China,and Chinese Academy of Sciences,ajoint team of three laboratories from the Institute of Biophysics of Chinese Academy of Sciences,led by Dr.Liu Zhenfeng(柳振峰),Dr.Zhang Xinzheng(章新政)and Dr.Li Mei(李梅)respectively,solved the structure of spinach photosystem II-LHCII supercom-

Assembly mechanism and energy transfer pathways of plant photosystem II-LHCII supercomplexes discovered through cryo-electron microscopy

Funded by the National Natural Science Foundation of China,Chinese Ministry of Science and Technology,and Chinese Academy of Sciences,ajoint team of three laboratories from the Institute of Biophysics of Chinese Academy of Sciences,namely Liu Zhenfeng’s(柳振峰),Zhang

Ultrafast Terahertz Probes of Charge Transfer and Recombination Pathway of CH_3NH_3PbI_3 Perovskites

We use transient terahertz photoconductivity measurements to demonstrate that upon optical excitation of CH_3NH_3PbI_3 perovskite, the hole transfer from CH_3NH_3PbI_3 into the organic hole-transporting material（HTM）Spiro-OMe TAD occurs on a sub-picosecond timescale. Second-order recombination is the dominant decay pathway at higher photo-excitation fluences as observed in neat CH_3NH_3PbI_3 films. In contrast, under similar experimental conditions, second-order recombination weakly contributes the relatively slow recombination between the electrons in the perovskite and the injected holes in HTM, as a loss mechanism at the CH_3NH_3PbI_3/Spiro-OMe TAD interface. Our results offer insights into the intrinsic photophysics of CH_3NH_3PbI_3-based perovskites with direct implications for photovoltaic devices and optoelectronic applications.

Cu single atoms embedded on hollow g-C_(3)N_(4)nanospheres with enhanced charge transfer and separation for efficient photocatalysis

Establishing an effective charge transfer mechanism in carbon nitride(g-C_(3)N_(4))to enhance its photocatalytic activity remains a limiting nuisance.Herein,the combination design of a single Cu atom with hollow g-C_(3)N_(4)nanospheres(Cu-N_(3)structure)has been proven to offer significant opportunities for this crucial challenge.Moreover,this structure endows two pathways for charge transfer in the reaction,namely,the N atoms in the three-dimensional planar structure are only bonded with a single Cu atom,and charge transfer occurs between the plane and the layered structure due to the bending of the interlayered g-C_(3)N_(4)hollow nanospheres.Notably,Cu-N_(3)and hollow nanosphere structures have been certified to greatly enhance the efficiency of photogenerated carrier separation and transfer between the layers and planes by ultrafast spectral analysis.As a result,this catalyst possesses unparalleled photocatalytic efficiency.Specifically,the hydrogen production rate up to 2040μmol h^(−1) g^(−1),which is 51 times that of pure C_(3)N_(4)under visible light conditions.The photocatalytic degradation performance of tetracycline and oxidation performance of benzene is also expressed,with a degradation rate of 100%,a conversion of 97.3%and a selectivity of 99.9%.This work focuses on the structure-activity relationship to provide the possibilities for the development of potential photocatalytic materials.

Aromatic and olefinic C–H alkenylation by catalysis with spirocyclic NHC Ru(Ⅳ) pincer complex

Catalyst innovation lies at the heart of transition-metal-catalyzed reaction development. In this article, we have explored the C(sp2)–H alkenylation activity with novel spirocyclic N-heterocyclic carbene(NHC)-based cyclometalated ruthenium pincer catalyst system, SNRu-X. After screening catalyst and condition, a high valent Ru(Ⅳ) dioxide(X = O_(2)) species has demonstrated superior reactivity in the catalytic alkenylation of aromatic and olefinic C–H bonds with unactivated alkenyl bromides and triflates. This reaction has achieved the easy construction of a wide range of(hetero)aromatic alkenes and dienes, in good to excellent yields with exclusive selectivity. Preliminary mechanistic studies indicate that this reaction may proceed through a single electron transfer(SET) triggered oxidative addition, by doing so, providing valuable complementary to classical alkenylation reactions that are dependent on activated alkenyl precursors.

Free-standing polymer-metal-organic framework membrane with high proton conductivity and water stability

As a new class of porous material,polymer-metal-organic framework(polyMOF)has attracted tremendous interests owing to their combined advantages of polymer and crystalline MOF.However,the poor film-forming ability of polyMOF limits its widespread application,especially in membrane separation area.Herein,for the first time,we demonstrate the fabrication of freestanding polyMOF membrane.The polyMOF nanosheets are synthesized by a polymer-assisted self-inhibition crystal growth strategy.Followed by self-assembly through vacuum filtration,a 20μm-thick free-standing polyMOF membrane is constructed.Benefiting from the inclusion of polymer with hydrophobic backbone and the continuously distributed non-coordinated hydrophilic groups along polymer chain,the polyMOF membrane attains excellent structure stability against water,as well as superior proton transfer property.Proton conductivity as high as 112 and 25.6 mS·cm^(–1)is obtained by this polyMOF membrane at 100%and 20%relative humidity(RH),respectively,which are two orders of magnitude higher than those of pristine MOF.The conductivity under low humidity(20%RH)is even over 8 times higher than that of commercial Nafion membrane(3 mS·cm^(–1)).This study may provide some guidance on the development of polyMOF membranes.

Iron-Catalyzed Cross-Electrophile Coupling of Inert C-O Bonds with Alkyl Bromides

An example of iron-catalyzed cross-electrophile couplingof inert C-O bonds with alkyl bromides via aniron/B_(2)pin_(2) catalytic system has been developed.Aryl and heteroaryl carbamates can smoothly undergothis transformation under mild conditions, deliveringthe alkylated products with good efficiency.This protocol exhibits good functional group compatibilityand enables the late-stage functionalizationof biorelevant compounds, thus providingexcellent opportunities for applications in medicinalchemistry. Control experiments and computationalstudies reveal that a high spin Fe(I/II/III) catalyticmechanism might be involved in this reactionthrough single electron transfer to activate alkylbromides, oxidative addition of aryl carbamates, andreductive elimination to form Csp^(2)-Csp^(3) bonds.

Film mulching reduces antibiotic resistance genes in the phyllosphere of lettuce

Phyllosphere is an important reservoir of antibiotic resistance genes(ARGs),but the transfer mechanism of ARGs from soil and air to phyllosphere remains unclear.This study demonstrated that soil-air-phyllosphere was the dominant ARG transfer pathway,and blocking it by film mulching can reduce typical phyllosphere ARGs in lettuce by 80.7%-98.7%(89.5%on average).To further eliminate phyllosphere ARGs in lettuce grown with film mulching,the internal soil-endosphere-phyllosphere transfer pathway deserves more attention.We analyzed the ARG hosts and the resistome in lettuce rhizosphere and phyllosphere with film mulching via hybrid Illumina-Nanopore sequencing.Pseudomonas sp.7SR1 was more abundant than other ARG hosts,accounting for 1.0%and 47.1%of the total bacteria in rhizosphere and phyllosphere,respectively.The species has flagella that can promote mobility and can excrete extracellular polymeric substances and/or surfactant-like microbial products,which benefits its colonization in the phyllosphere.Impeding the migration of Pseudomonas sp.7SR1 via the soil-endosphere-phyllosphere pathway would be effective to further reduce ARGs in phyllosphere.Multidrug resistant genes were predominant in phyllosphere(40.3%of the total),and 87.6%of the phyllosphere ARGs were located on chromosomes,indicating relatively low horizontal gene transfer(HGT)potentials.This study provides insights into the transfer mechanism,hosts,and control strategies of phyllosphere ARGs in typical plants.

Dramatically Enhanced Visible-light-responsive H_(2) Evolution of Cd_(1-x)Zn_(x)S via the Synergistic Effect of Ni_(2)P and 1T/2H MoS_(2) Cocatalysts

Photocatalytic hydrogen generation from water-splitting holds huge promise for resolving the current energy shortage and environmental issues.Nevertheless,it is still challenging so far to develop non-noble-metal photocatalysts which are efficient toward solar-powered hydrogen evolution reaction(HER).In this work,through an ultrasonic water-bath strategy combined with solvothermal and electrostatic assembly processes,we obtain homogeneous Cd_(1-x)Zn_(x)S–Ni_(2)P–MoS_(2) hybrid nano-spheres consisting of Cd_(1-x)Zn_(x)S solid solutions decorated by Ni_(2)P and 1 T/2 H MoS_(2) cocatalysts,which demonstrate excellent activity and stability for visible-light-responsive(λ>420 nm)H_(2) production.Specifically,the Cd_(1-x)Zn_(x)S-Ni_(2)P-MoS_(2) nano-spheres with 2 wt%Ni_(2)P and 0.2 wt%MoS_(2)(CZ_(0.7)S–2 N–0.2 M)exhibit the optimal HER activity of 55.77 mmol·g^(-1)·h^(-1),about 47 and 32 times more than that of CZ_(0.7)S and Pt–CZ_(0.7)S,respectively.The outstanding HER performance of Cd_(1-x)Zn_(x)S–Ni_(2)P–MoS_(2) can be ascribed to the presence of abundant HER active sites in Ni2 P nanoparticles and 1 T/2 H MoS_(2) nanosheets as well as the effective transfer and separation of charge carriers.Moreover,the coupling sequence of cocatalysts in Cd_(1-x)Zn_(x)S–Ni_(2)P–MoS_(2) is found to be critical in the regulation of charge transfer pathways and thus the resultant photocatalytic efficiency.The results displayed here could facilitate the engineering of high-performance photocatalysts employing multi-component cocatalysts for sustainable solar-to-fuel conversion.

Endow activated carbon with the ability to activate peroxymonosulfate for the treatment of refractory organics

Herein,we demonstrated that various activated carbons could be endowed with high ability activating peroxymonosulfate(PMS)just through pyrolysis for the degradation of various organic pollutants.The ofloxacin(OFX)was proved to be degraded rather than adsorbed in the advanced oxidation processes.The catalyst showed good stability and could be recovered by simple pyrolysis showing the initial activity.The defects were identified as active sites of the catalyst,andπ-π^(*)shake up was related to the catalyst activity.Mediated electron transfer was verified to be responsible for the degradation of OFX.The inhibition effect of furfuryl alcohol(FFA)on the degradation of contaminant was proved to be insufficient to verify^(1)O_(2).The main OFX degradation intermediates were identified by LC-MS,and possible degradation pathways were proposed.This study provided a simple way for the development of low-cost,metal-free,and high-efficient carbonaceous materials to activate PMS in advanced oxidation processes,and proposed new insights for the exploration of PMS activation mechanism.

A green strategy for porous biochar fabrication with superior capacity for peroxydisulfate activation to degrade sulfadiazine:the cooperative role of C-sp^(3) and specific surface area

Metal-free porous biochars are popularly utilized as catalysts for peroxydisulfate(PDS)activation.The enhancement effect of PDS activation of porous biochars fabricated by employing both hard template and alkali metal activating agent has not been explored completely.In addition,the role of the inherent carbon defect in PDS activation has not been clearly elucidated.Hence,a series of carbonaceous catalysts were fabricated using a sole template(KCl),a sole activating agent(Na_(2)S_(2)O_(3))or a combination of template and activating agent(KCl/Na_(2)S_(2)O_(3),KCl/KHCO_(3),KCl/NaHCO_(3),and KCl/Na_(2)C_(2)O_(4)),to systematically investigate the effect of specific surface area(SSA)and intrinsic defect of porous biochar on its PDS activation ability.The biochar synthesized by KCl and Na_(2)S_(2)O_(3)(SK-C)exhibited the optimum degradation performance.The SK-C was found to possess an interconnected hollow cage with three-dimensional mesh structure showing the largest surface area,pore volume and C-sp^(3) edge defect content among all the catalysts,which explained its paramount catalytic ability.The SSA and C-sp^(3) content together can determine the catalytic performance in a quantitative relationship.The single electron transfer pathway from SDZ to inner-sphere bound SK-C/PDS*was the protagonist of pollutant oxidation.The degradation intermediates were detected and recognized and their toxicities were evaluated.This study for the first time comprehensively identified the synergistic effect between the SSA and inherent defects on improving the catalytic performance of biochar for PDS activation to removal contaminants.