Controllable design of Zn-Ni-P on g-C_3N_4 for efficient photocatalytic hydrogen production

Synthesizing a stable and efficient photocatalyst has been the most important research goal up to now. Owing to the dominant performance of g-C3N4 (graphitized carbonitride), an ordered assemble of a composite photocatalyst, Zn-Ni-P@g-C3N4, was successfully designed and controllably prepared for highly efficient photocatalytic H2 evolution. The electron transport routes were successfully adjusted and the H2 evolution was greatly improved. The maximum amount of H2 evolved reached about 531.2 μmol for 5 h over Zn-Ni-P@g-C3N4 photocatalyst with a molar ratio of Zn to Ni of 1:3 under illumination of 5 W LED white light (wavelength 420 nm). The H2 evolution rate was 54.7 times higher than that over pure g-C3N4. Moreover, no obvious reduction in the photocatalytic activity was observed even after 4 cycles of H2 production for 5 h. This synergistically increased effect was confirmed through the results of characterizations such as XRD, TEM, SEM, XPS, N2 adsorption, UV-vis DRS, transient photocurrent, FT-IR, transient fluorescence, and Mott-Schottky studies. These studies showed that the Zn-Ni-P nanoparticles modified on g-C3N4 provide more active sites and improve the efficiency of photogenerated charge separation. In addition, the possible mechanism of photocatalytic H2 production is proposed.

Solvothermal synthesis and characterization of nanocrystalline vanadium-chromium composite oxides and catalytic ammoxidation of 2,6-dichlorotoluene

Vanadium‐chromium oxides(VCrO)were usually prepared by high‐temperature solid‐state reactions;however,mixed phases were frequently produced and the morphology of the products was not well controlled.In this work,we prepared amorphous VCrO precursors by using V2O5 and CrO3 and alcohols or mixtures of alcohol and water via solvothermal reaction at 180°C.The precursors were then calcined under nitrogen at various temperatures.The products were characterized by powder X‐ray diffraction,transmission electron microscopy,and X‐ray photoelectron spectroscopy.It was revealed that pure‐phase nanocrystalline orthorhombic CrVO4 was obtained when methanol or methanol/water was used as the solvothermal medium and the precursor was calcined at 700°C.The size of the CrVO4 crystals was around 500 nm when methanol was used,whereas it reduced significantly to less than 50 nm when a mixture of methanol and water was used.The sizes could be effectively tuned from 10 to 50 nm by varying the methanol/water volume ratio.To the best of our knowledge,this is the first report on the synthesis of pure‐phase CrVO4 nanocrystals.The nano‐CrVO4 showed almost the highest catalytic activity for the ammoxidation of 2,6‐dichlorotoluene to 2,6‐dichlorobenzonitrile among the reported bi‐component composite oxides,owing to its smaller particle size,larger specific surface area,and more exposed active centers.

Prolonging charge-separation states by doping lanthanide-ions into {001}/{101} facets-coexposed TiO_2 nanosheets for enhancing photocatalytic H_2 evolution

Ultrathin TiO2 nanosheets with coexposed {001}/{101} facets have attracted considerable attention because of their high photocatalytic activity. However, the charge-separated states in the TiO2 nanosheets must be extended to further enhance their photocatalytic activity for H2 evolution. Herein, we present a successful attempt to selectively dope lanthanide ions into the {101} facets of ultrathin TiO2 nanosheets with coexposed {001}/{101} facets through a facile one-step solvothermal method. The lanthanide doping slightly extended the light-harvesting region and markedly improved the charge-separated states of the TiO2 nanosheets as evidenced by UV-vis absorption and steady-state/transient photoluminescence spectra. Upon simulated sunlight irradiation, we observed a 4.2-fold enhancement in the photocatalytic H2 evolution activity of optimal Yb3+-doped TiO2 nanosheets compared to that of their undoped counterparts. Furthermore, when Pt nanoparticles were used as cocatalysts to reduce the H2 overpotential in this system, the photocatalytic activity enhancement factor increased to 8.5. By combining these results with those of control experiments, we confirmed that the extended charge-separated states play the main role in the enhancement of the photocatalytic H2 evolution activity of lanthanide-doped TiO2 nanosheets with coexposed {001}/{101} facets.

Efficient photocatalytic hydrogen evolution over graphdiyne boosted with a cobalt sulfide formed S-scheme heterojunction

Graphdiyne(GDY,g-C_(n)H_(2n-2)),a novel two-dimensional carbon hybrid material,has attracted significant attention owing to its unique and excellent properties.As a new type of carbon material,GDY has a layered structure and can be used in the field of photocatalytic water splitting.Therefore,herein,new progress in the preparation of graphene using Cu I powder as a catalytic material and the combination of a facile hydrothermal method to prepare a new composite material,Co_(9)S_(8)-GDY-Cu I,is reported.The hydrogen production activity of Co9S8-GDY-Cu I in the sensitization system reached 1411.82μmol g^(-1) h^(-1),which is 10.29 times that of pure GDY.A series of characterization techniques were used to provide evidence for the successful preparation of the material and its superior photocatalytic activity.Raman spectroscopy showed that the material contains acetylenic bonds,and the X-ray photoelectron spectroscopy carbon fitting peaks indicated the presence of C-C(sp^(2))and C-C(sp),further demonstrating that GDY was successfully prepared.A possible reaction mechanism was proposed by making use of UV-visible diffuse reflectance and Mott-Schottky analyses.The results showed that a double S-scheme heterojunction was constructed between the samples,which effectively accelerated the separation and transfer of electrons.In addition,the introduction of Co9S8 nanoparticles greatly improved the visible light absorption capacity of Co_(9)S_(8)-GDY-Cu I.Photoluminescence spectroscopy and related electrochemical characterization further proved that recombination of the electron-hole pairs in the composite material was effectively suppressed.

Enhanced visible photocatalytic activity of TiO_2 hollow boxes modified by methionine for RhB degradation and NO oxidation

Hierarchical TiO2 hollow nanoboxes(TiO2‐HNBs)assembled from TiO2 nanosheets(TiO2‐NSs)show improved photoreactivity when compared with the building blocks of discrete TiO2‐NSs.However,TiO2‐HNBs can only be excited by ultraviolet light.In this paper,visible‐light‐responsive N and S co‐doped TiO2‐HNBs were prepared by calcining the mixture of cubic TiOF2 and methionine(C5H11NO2S),a N‐and S‐containing biomacromolecule.The effect of calcination temperature on the structure and performance of the TiO2‐HNBs was systematically studied.It was found that methionine can prevent TiOF2‐to‐anatase TiO2 phase transformation.Both N and S elements are doped into the lattice of TiO2‐HNBs when the mixture of TiOF2 and methionine undergoes calcination at 400°C,which is responsible for the visible‐light response.When compared with that of pure 400°C‐calcined TiO2‐HNBs(T400),the photoreactivity of 400°C‐calcined methionine‐modified TiO2‐HNBs(TM400)improves 1.53 times in photocatalytic degradation of rhodamine‐B dye under visible irradiation(?>420 nm).The enhanced visible photoreactivity of methionine‐modified TiO2‐HNBs is also confirmed by photocatalytic oxidation of NO.The successful doping of N and S elements into the lattice of TiO2‐HNBs,resulting in the improved light‐harvesting ability and efficient separation of photo‐generated electron‐hole pairs,is responsible for the enhanced visible photocatalytic activity of methionine‐modified TiO2‐HNBs.The photoreactivity of methionine modified TiO2‐HNBs remains nearly unchanged even after being recycled five times,indicating its promising use in practical applications.

One-pot topotactic synthesis of Ti^(3+) self-doped 3D TiO_2 hollow nanoboxes with enhanced visible light response

Ti^（3＋） self-doped anatase three-dimensional（3D） TiO_2 hollow nanoboxes were synthesized via a topological transformation process involving template participation by a facile one-pot hydrothermal treatment with an ethanol solution of zinc powder and TiOF_2. It is worth noting that the 3D TiO_2 hollow nanoboxes are assembled from six single-crystal nanosheets and have dominant exposure of the {001} facets. It is found from EPR spectra that adding zinc powder is an environment-friendly and effective strategy to introduce Ti^（3＋） and oxygen vacancy（Ov） into the bulk of 3D hollow nanoboxes rather than the surface, which is responsible for their enhanced visible photocatalytic properties.The photocatalytic activity was evaluated by measuring the formation rate of hydroxide free radicals using 7-hydroxycoumarin as a probe. The sample prepared with zinc/TiOF_2 mass ratio of0.25 exhibited the highest RhB photodegradation activity under visible-light irradiation with a degradation rate of 96%, which is 4.0-times higher than that of pure TiO_2. The results suggest a novel approach to construct in-situ 3D hierarchical TiO_2 hollow nanoboxes doped with Ti^（3＋） and Ov without introducing any impurity elements for superior visible-light photocatalytic activity.

Highly photoreactive TiO_2 hollow microspheres with super thermal stability for acetone oxidation

TiO2hollow microspheres(TiO2‐HMSs)have attracted much attention because of their high photoreactivity,low density,and good permeability.However,anatase TiO2‐HMSs have poor thermal stability.In this study,surface‐fluorinated TiO2‐HMSs were assembled from hollow nanoparticles by the hydrothermal reaction of the mixed Ti(SO4)2–NH4HF–H2O2solution at180°C.The effect of the calcination temperature on the structure and photoreactivity of the TiO2‐HMSs was systematically investigated,which was evaluated by photocatalytic oxidation of acetone in air under ultraviolet irradiation.We found that after calcination at300°C,the photoreactivity of the TiO2‐HMSs decreases from1.39×10?3min?1(TiO2‐HMS precursor)to0.82×10?3min?1because of removal of surface‐adsorbed fluoride ions.With increasing calcination temperature from300to900°C,the building blocks of the TiO2‐HMSs evolve from truncated bipyramidal shaped hollow nanoparticles to round solid nanoparticles,and the photoreactivity of the TiO2‐HMSs steady increases from0.82×10?3to2.09×10?3min?1because of enhanced crystallization.Further increasing the calcination temperature to1000and1100°C results in a decrease of the photoreactivity,which is ascribed to a sharp decrease of the Brunauer–Emmett–Teller surface area and the beginning of the anatase–rutile phase transformation at1100°C.The effect of surface‐adsorbed fluoride ions on the thermal stability of the TiO2‐HMSs is also discussed.

Mechanochemical preparation and application of graphdiyne coupled with CdSe nanoparticles for efficient photocatalytic hydrogen production

Graphdiyne(GDY)has attracted considerable attention as a new two-dimensional(2D)carbon hybrid material because of its good conductivity,adjustable electronic structure,and special electron transfer enhancement properties.GDY has great potential in the field of photocatalytic water splitting for hydrogen evolution,owing to its unique properties.In this study,GDY was successfully prepared by the mechanochemical coupling of precursors C_(6)Br_(6) and CaC_(2) using a ball-milling approach.The prepared GDY,especially its microstructure and composition,was well characterized using different techniques such as X-ray diffraction,scanning electron microscopy,transmission electron microscopy,X-ray photoelectron spectroscopy(XPS),Fourier-transform infrared,and Raman characterization techniques.By exploiting the unique two-dimensional(2D)structure and outstanding light absorption properties of GDY,GDY/CdSe 2D/0D heterojunctions were successfully established and applied to photocatalytic hydrogen evolution.The hydrogen evolution activity of GDY/CdSe-20,a type of composite material,reached 6470μmol g^(-1) h^(-1),which is 461 and 40 times higher than that of GDY and CdSe,respectively.Moreover,the fine electrical conductivity of GDY enabled rapid and effective transfer of the photogenerated electrons in CdSe into the hydrogen evolution reaction.The transfer path of the photogenerated electrons was studied through XPS with in situ irradiation,and a reasonable mechanism for the hydrogen evolution reaction was proposed.This study provides a feasible approach for the large-scale preparation of GDY and demonstrates the prospects of GDY in the field of photocatalysis.

Optimization of Wickerhamomyces anomalus Fermentation Conditions for Pectinase Production Based on Wet Processing of Arabica Coffee in Yunnan Province

In order to improve the pectin-degrading efficiency in wet processing of Arabica coffee in Yunnan, Box-Behnken design and single factor experiment were used to optimize the fermentation conditions of five pectinolytic Wickerhamomyces anomalus strains from the fermentation broth of Arabica coffee in Baoshan, Yunnan during wet processing with pectase activity as an indicator. The results showed that the five strains all synthesized pectin lyase(PL), polygalacturonase(PG), and pectin methylesterase(PM).Among them, strain CAP5 had strong ability to produce PG and PL,while strain CAP4 secreted a large amount of PM. Under optimized conditions, the activity of PG, PL, and PM of the five strains came in at 250.17~411.20 U/mL, 12.98~16.55 U/mL, and 208.52~322.83 U/mL,respectively. The four factors of nitrogen source concentration,fermentation time, Mn2+ concentration, and pH value were optimized and the optimal pectinase-producing fermentation conditions for five strains were as follows: peptone 2.2 g/L, fermentation time 30 h, Mn2+ 1.5 mmol/L, and pH 4.3. After fermentation under the optimized conditions, the maximum PG activity of CAP5 amounted to 411.20 U/mL, 114.03% higher than that before optimization.Meanwhile, the PG activity of strains CAP3, CAP4, CAP8, and CAP10 increased by 86.74%, 114.55%, 65.79%, and 66.07%,respectively, and the activity of PL and PM of the five strains rose 150.35%~218.56% and 341.07%~418.52%, respectively. These findings suggested that W. anomalus strains could be used as coffee starter and had great potential for the lysis of pectin.

现代企业制度下共青团工作的新思路

建立社会主义市场经济体制,其中一个重要内容,就是建立现代企业制度。这项改革对企业生产经营是一个大挑战,对企业内共青团工作也是一个大挑战。如何使团的工作主动适应改革,在改革中寻求发展,已成为广大团干的新课题。 1 挑战与机遇随着企业改革的不断深化,随着现代企业制度的逐步建立,团的工作遇到了许多困难与问题,这也就是我们通常所说的挑战,主要表现在以下五个方面: 第一,思想活跃与方法单一的矛盾。当代青年生活在一个开放的社会里,其思想十分活跃,而团的工作内容和教育方法传统而单一,已越来越滞后于当代青年的变化和要求。

刍议企业形象的效应与塑造

当前,我国正从传统的计划经济体制向社会主义市场经济体制转换,我国经济正从数量速度型向质量效益型转换,在这一过程中,企业之间的竞争愈演愈烈,其表现不仅仅是产品质量的竞争,技术的竞争,价格的竞争,而且很大程度上扩展到企业形象上的竞争。实践证明,谁在社会公众中有着美好的企业形象,谁就拥有一笔巨大的无形资产,并从中获得巨大的经济效益,谁就能在竞争中赢得优势,击败对手,立于不败之地。

A novel S-scheme 3D ZnIn_(2)S_(4)/WO_(3) heterostructure for improved hydrogen production under visible light irradiation

In-plane epitaxial growth of ZnIn_(2)S_(4) nanosheets on the surface of hexagonal phase WO_(3) nanorods was achieved by a facile solvothermal method.The unique 3D heterostructure not only enlarged the specific surface area,but also red-shifted the absorption edge from 381 to 476 nm to improve the light harvesting ability,which largely enhanced the photocatalytic hydrogen evolution.The H_(2) production rate of the best performing ZnIn_(2)S_(4)/WO_(3) photocatalyst(ZIS-2.5/W,the material with a molar rate of ZnIn_(2)S_(4)(ZIS)to WO_(3)(W)of 2.5)was 300μmol·g^(–1)·h^(–1),around 417 times and 2 times higher than the rates of pristine WO_(3) and ZnIn_(2)S_(4),respectively.The apparent quantum efficiency for ZIS-2.5/W composite was up to 2.81%at 400 nm.Based on the difference in Fermi levels between WO_(3) and ZnIn_(2)S_(4),and the distribution of the redox active sites on WO_(3)/ZnIn_(2)S_(4) heterostructure,a S-scheme electron transfer mechanism was proposed to illustrate the improved photocatalytic activity of WO_(3)/ZnIn_(2)S_(4) heterojunction,which not only stimulated the spatial separation of the photogenerated charge carriers,but also maintained the strong reduction/oxidation ability of the photocatalyst.

Growth of Cu/SSZ-13 on SiC for selective catalytic reduction of NO with NH_3

Silicon carbide(SiC)was used as a support for SSZ‐13zeolite in an attempt to improve the high‐temperature stability and activity of Cu/SSZ‐13in the selective catalytic reduction(SCR)of NO with NH3.SSZ‐13was grown via a hydrothermal method using the silicon and silica contained in SiC as the source of silicon,which led to the formation of a chemically bonded SSZ‐13layer on SiC.Characterization using X‐ray diffraction,scanning electron microscopy,and N2adsorption‐desorption isotherms revealed that the alkali content strongly affected the purity of zeolite and the crystallization time affected the coverage and crystallinity of the zeolite layer.Upon ion exchange,the resulting Cu/SSZ‐13@SiC catalyst exhibited enhanced activity in NH3‐SCR in the high‐temperature region compared with the unsupported Cu/SSZ‐13.Thus,the application temperature was extended with the use of SiC as the support.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.

女职工提高自身竞争力所面临的障碍及对策

在我国,男女是平等的,这就是说,男女都享有法律所规定的同样的权力和义务。但是,在我们的社会生活里,男女之间却存在着事实上的不平等。君不闻,国家机关女干部仅占1/5;君不见,女大中专毕业生分配困难重重,有些接收单位甚至说:"宁可安排三个男的,不可接收一个女的。"这就是事实上的不平等。这是为什么?这主要是女职工竞争力不强。如何改变女职工竞争力不强的现实,真正做到男女平等,不仅是在法律地位上的平等,而且是现实生活中事实上的平等,笔者认为。

企业培养选拔女干部刍议

培养选拔女干部,是党的干部工作的一项重要任务,建国以来,女干部队伍不断壮大。现在,我国已有女干部890多万,占干部总数的28.9%,担任县处级以上领导职务的女干部也逐渐增加。但是,培养选拔女干部仍然是当前干部工作中的一个薄弱环节,其突出表现是各级领导班子中女干部的比例偏低,而且层次越高,比例越小。具体到涟钢,目前,全公司共有干部5822人,女干部1948人;中层干部1407人,女中层干部97人。上述比例。

浅谈企业下岗职工再就业存在的问题及对策

当前,实施再就业工程已成为深化企业改革,促进社会稳定的重大战略措施,是一项十分艰巨的工程。笔者就当前企业下岗职工再就业存在的问题谈谈自己的看法并提出对策。 1 再就业存在的问题 a.人们的就业观亟待转变。在当前形势下,要在全社会进一步树立依靠诚实劳功,取得合法收入就是就业的观念。这是一个复杂的社会系统工程。

对涟钢待业青年的调查与思考

为切实做好涟钢待业青年的教育管理工作,我们在1995年5月初到7月底的两个多月时间里,采取登记、建卡、造册、统计和个别交流、座谈等形式,对涟钢待业青年状况作了比较全面的摸底调查。在此,提出我们的一些看法和建议,与大家交流。

试论如何加强对领导干部的有效监督

如果说,一个单位,一个地方,一个国家是列火车,那么领导干部就是这列火车的车头。"火车跑得快,全靠车头带。"单位、地方、国家要发展,要生存,如果没有好的领导干部,那是不可能实现的,正如一列火车没有车头是不可能开动的。好的领导干部不是天生的,他不仅需要培养,还需要有效的监督。加强对领导干部的有效监督。

对“两劳释放”人员管理教育问题初探

近年来,我公司根据上级有关文件精神,对企业原职工中曾因违法犯罪,被政法部门判刑或劳教人员(简称"两劳释放"人员)不再遣送回原籍,而由企业内部"消化"。对这批人员如何管理,不仅关系到"两劳释放"人员能否振作精神,重新做人的问题,而且还关系到社会安定团结的问题。本文就企业如何加强对"两劳释放"人员管理作些肤浅的探讨。

努力开创待业青年思想教育和管理工作的新局面

家委团委是1993年6月成立的,具体负责涟钢待业青年的思想教育和管理工作。家委团委成立后的半年时间里,我们以加强团组织自身建设为保证,以教育青年、服务青年为根本,坚持从严建团,突出"四抓"、提高"四力",开展了各类活动,为涟钢的综合治理和百万吨钢的实现作出了贡献。