Influence of O-O formation pathways and charge transfer mediator on lipid bilayer membrane-like photoanodes for water oxidation

Inspired by the function of crucial components in photosystemⅡ(PSⅡ),electrochemical and dyesensitized photoelectrochemical(DSPEC)water oxidation devices were constructed by the selfassembly of well-designed amphipathic Ru(bda)-based catalysts(bda=2,2'-bipyrdine-6,6'-dicarbonoxyl acid)and aliphatic chain decorated electrode surfaces,forming lipid bilayer membrane(LBM)-like structures.The Ru(bda)catalysts on electrode-supported LBM films demonstrated remarkable water oxidation performance with different O-O formation mechanisms.However,compared to the slow charge transfer process,the O-O formation pathways did not determine the PEC water oxidation efficiency of the dyesensitized photoanodes,and the different reaction rates for similar catalysts with different catalytic paths did not determine the PEC performance of the DSPECs.Instead,charge transfer plays a decisive role in the PEC water oxidation rate.When an indolo[3,2-b]carbazole derivative was introduced between the Ru(bda)catalysts and aliphatic chain-modified photosensitizer in LBM films,serving as a charge transfer mediator for the tyrosine-histidine pair in PSⅡ,the PEC water oxidation performance of the corresponding photoanodes was dramatically enhanced.

Polymeric viologen-based electron transfer mediator for improving the photoelectrochemical water splitting on Sb_(2)Se_(3) photocathode

The photogenerated charge carrier separation and transportation of inside photocathodes can greatly influence the performance of photoelectrochemical(PEC)H2 production devices.Coupling TiO_(2) with p-type semiconductors to construct heterojunction structures is one of the most widely used strategies to facilitate charge separation and transportation.However,the band position of TiO_(2) could not perfectly match with all p-type semiconductors.Here,taking antimony selenide(Sb_(2)Se_(3))as an example,a rational strategy was developed by introducing a viologen electron transfer mediator(ETM)containing polymeric film(poly-1,1′-dially-[4,4′-bipyridine]-1,1′-diium,denoted as PV^(2+))at the interface between Sb_(2)Se_(3) and TiO_(2) to regulate the energy band alignment,which could inhibit the recombination of photogenerated charge carriers of interfaces.With Pt as a catalyst,the constructed Sb_(2)Se_(3)/PV^(2+)/TiO_(2)/Pt photocathode showed a superior PEC hydrogen generation activity with a photocurrent density of−18.6 mA cm^(-2) vs.a reversible hydrogen electrode(RHE)and a half-cell solar-to-hydrogen efficiency(HC-STH)of 1.54%at 0.17 V vs.RHE,which was much better than that of the related Sb_(2)Se_(3)/TiO_(2)/Pt photocathode without PV^(2+)(−9.8 mA cm^(-2),0.51%at 0.10 V vs.RHE).

禾本科三倍体:形成、鉴定与利用

禾本科三倍体的形成途径包括2n配子融合、倍性间杂交、多精受精和胚乳培养。其中,2n配子融合和倍性间杂交分别为自然界和人工合成三倍体的主要途径。该文介绍了形态学观测、染色体分析、流式细胞术和分子标记等倍性鉴定方法在禾本科三倍体中的应用及其优缺点。目前,三倍体在禾谷类作物中无直接应用价值,但可作为通往多倍体、非整倍体和转移异源基因的遗传桥梁。多年生禾本科三倍体(特别是异源三倍体)在饲草或能源作物中已得到广泛应用,在该类型禾本科作物中均可直接尝试三倍体育种。多倍体的三倍体育种和无融合生殖三倍体育种可作为未来禾本科三倍体的研究方向。三倍性胚乳培养可以一步合成三倍体,多精受精可以实现遗传上3个不同基因组的一步融合,在三倍体研究中应予以重视。鉴于2n配子融合、多精受精的稀有特性和倍性间杂交、胚乳培养频繁的染色体变异,高通量三倍体鉴定技术的发展将是三倍体研究实现突破的关键。

玉米野生近缘种属研究利用进展

作物的近缘野生种质遗传多样性是作物遗传育种家应对气候变化、虫害和病害等胁迫的不可或缺资源.玉米(Zea mays)的野生近缘种属主要指玉蜀黍属中的大刍草种和摩擦禾属(Tripsacum L.),它们蕴涵着栽培玉米不具有的耐盐、耐冷和抗病虫等优良特性,对扩大玉米种质的遗传基础和改进目前生产运用的玉米杂交种的特异性状具有重大意义.本文对大刍草和摩擦禾种质资源的系统分化、植物生态地理学属性、可杂交性和居群间的基因流动、基因组学数据、重要性状的基因定位克隆及育种应用进行了系统论述,并对未来如何高效保存与利用这些遗传资源、发掘新基因和高效种质创新利用进行了展望,旨在为玉米近缘野生资源多样性的了解和利用远缘杂交进行玉米遗传改良提供参考.

Switching the O-O Bond Formation Pathways of Ru-pda Water Oxidation Catalyst by Third Coordination Sphere Engineering

Water oxidation is a vital anodic reaction for renewable fuel generation via electrochemical-and photoelectrochemical-driven water splitting or CO_(2)reduction.Ruthenium complexes,such as Ru-bda family,have been shown as highly efficient wateroxidation catalysts(WOCs),particularly when they undergo a bimolecular O-O bond formation pathway.In this study,a novel Ru(pda)-type(pda^(2–)=1,10-phenanthroline-2,9-dicarboxylate)molecular WOC with 4-vinylpyridine axial ligands was immobilized on the glassy carbon electrode surface by electrochemical polymerization.Electrochemical kinetic studies revealed that this homocoupling polymer catalyzes water oxidation through a bimolecular radical coupling pathway,where interaction between two Ru(pda)–oxyl moieties(I2M)forms the O-O bond.The calculated barrier of the I2M pathway by densityfunctional theory(DFT)is significantly lower than the barrier of a water nucleophilic attack(WNA)pathway.By using this polymerization strategy,the Ru centers are brought closer in the distance,and the O-O bond formation pathway by the Ru(pda)catalyst is switched from WNA in a homogeneous molecular catalytic system to I2M in the polymerized film,providing some deep insights into the importance of third coordination sphere engineering of the water oxidation catalyst.

Promotion of the oxygen evolution performance of Ni–Fe layered hydroxides via the introduction of a proton-transfer mediator anion

Developing efficient catalysts with high durability and activity for the oxygen evolution reaction(OER)is imperative for sustainable energy conversion technologies,including hydrogen generation and CO_(2) reduction,as well as other electrochemical energy storage systems.To this end,a comprehensive understanding of the mechanism for the water oxidation reaction is vital.Herein,a surfactant,nonafluoro-1-butanesulfonate(FBS),was introduced into Ni-Fe layered double hydroxide(Ni Fe-FBS/CFP)via electrochemical deposition on the surface of a carbon fiber paper(CFP)substrate.The as-prepared Ni Fe-FBS/CFP electrode exhibited excellent catalytic activities for OER compared to the Ni-Fe layered double hydroxide based electrode(Ni Fe-LDH/CFP),an excellent stability of 15 h,and an ultralow Tafel slope of 25.8 m V dec-1.Furthermore,by combining the results of p H-dependent kinetics investigations,chemical probing,proton inventory studies,and isotopic and atom-protontransfer measurements,it was observed that a proton-transfer process controls the reaction rates of both the Ni Fe-LDH and Ni Fe-FBS catalysts,and the residual sulfonate groups serve as proton transfer mediator to accelerate the proton transfer rate.