Pt/CexZr1-xO2催化剂上丙烷完全氧化性能研究

采用沉淀法制备了ZrO2,CeO2和Ce0.7Zr0.3O2载体,并用浸渍法制备负载型Pt催化剂。考察了500和900℃焙烧催化剂的丙烷完全氧化性能和水汽对丙烷氧化反应的影响。对于500℃焙烧的催化剂,催化剂的丙烷氧化活性顺序为:Pt/ZrO2-500>Pt/CeO2-500>Pt/Ce0.7Zr0.3O2-500;而经900℃焙烧的催化剂活性顺序为:Pt/ZrO2-900>Pt/Ce0.7Zr0.3O2-900>Pt/CeO2-900。反应气氛中水汽的存在对两种Pt/ZrO2催化剂的活性均有抑制作用(T50温度均提高了10~15℃);而对于Pt/CeO2-500催化剂有抑制作用(T50温度提高10℃),但对Pt/CeO2-900催化剂活性有促进作用(T50温度下降25℃);对于两种Pt/Ce0.7Zr0.3O2催化剂活性具有促进作用(T50温度均下降5~25℃)。表征结果表明催化剂的活性与其表面Pt物种价态密切相关,催化剂表面上Pt0物种有利于活性的提高。Pt/Ce0.7Zr0.3O2-500催化剂中只含有氧化态Pt物种(Pt^2+),而Pt/Ce0.7Zr0.3O2-900催化剂中则含有部分金属态Pt物种,因此其活性高于Pt/Ce0.7Zr0.3O2-500催化剂。     

Thermal and Nonthermal Effects in Plasmon-Mediated Electrochemistry at Nanostructured Ag Electrodes

Hot carriers (HCs) and thermal effects, stemming from plasmon decays, are crucial for most plasmonic applications. However, quantifying these two effects remains extremely challenging due to the experimental difficulty in accurately measuring the temperature at reaction sites. Herein, we provide a novel strategy to disentangle HCs from photothermal effects based on the different traits of heat dissipation (long range) and HCs transport (short range), and quantitatively uncover the dominant and potential-dependent role of photothermal effect by investigating the rapid- and slow-response currents in plasmon-mediated electrochemistry at nanostructured Ag electrode. Furthermore, the plasmoelectric surface potential is found to contribute to the rapid-response currents, which is absent in the previous studies.     

Metal–Organic Framework Membrane Nanopores as Biomimetic Photoresponsive Ion Channels and Photodriven Ion Pumps

Biological ion channels and ion pumps with sub-nanometer sizes modulate ion transport in response to external stimuli. Realizing such functions with sub-nanometer solid-state nanopores has been an important topic with wide practical applications. Herein, we demonstrate a biomimetic photoresponsive ion channel and photodriven ion pump using a porphyrin-based metal–organic framework membrane with pore sizes comparable to hydrated ions. We show that the molecular-size pores enable precise and robust optoelectronic ion transport modulation in a broad range of concentrations, unparalleled with conventional solid-state nanopores. Upon decoration with platinum nanoparticles to form a Schottky barrier photodiode, photovoltage across the membrane is generated with “uphill” ion transport from low concentration to high concentration. These results may spark applications in energy conversion, ion sieving, and artificial photosynthesis.     

Fabrication of Microporous Metal–Organic Frameworks in Uninterrupted Mesoporous Tunnels: Hierarchical Structure for Efficient Trypsin Immobilization and Stabilization

Hierarchically porous metal–organic frameworks (HP-MOFs) are promising in various applications. Most reported HP-MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as-prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor-induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record-high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites.     

Defect passivation of CsPbI_2Br perovskites through Zn(Ⅱ) doping:toward efficient and stable solar cells

Defect passivation is an important strategy to achieve perovskite solar cells(PVSCs) with enhanced power conversion efficiencies(PCEs) and improved stability because the trap states induced by defects in the interfaces and grain boundaries of perovskites are harmful to both large open circuit voltage and high photocurrent of devices. Here, zinc cations(Zn~(2+)) were used as a dopant to passivate defects of the CsPbI_2Br perovskite leading to Zn~(2+)-doped CsPbI_2Br film with fewer trap states, improved charge transportation, and enhanced light-harvesting ability. Thus, the best-performance PVSC based on CsPbI2 Br with the optimal Zn~(2+)doping shows a higher PCE of 12.16% with a larger open-circuit voltage(V_(OC)) of 1.236 V, an improved shortcircuit current(J_(SC)) of 15.61 mA cm~(-2) in comparison with the control device based on the pure CsPbI_2Br which exhibits a PCE of 10.21% with a V_(OC)of 1.123 V, a J_(SC)of 13.27 mA cm~(-2). Time-resolved photoluminescence results show that the Zn~(2+)doping leads to perovskite film with extended photoluminescence lifetime which means a longer diffusion length and subsequently enhanced photocurrent and open circuit voltage. This work provides a simple strategy to boost the performance of PVSCs through Zn~(2+)doping.     

Thermal Efficiency of Solar Steam Generation Approaching 100 % through Capillary Water Transport

Solar‐driven interfacial water evaporation yield is severely limited by the low efficiency of solar thermal energy. Herein, the injection control technique (ICT) achieves a capillary water state in rGO foam and effectively adjusts the water motion mode therein. Forming an appropriate amount of capillary water in the 3D graphene foam can greatly increase the vapor escape channel, by ensuring that the micrometer‐sized pore channels do not become completely blocked by water and by exposing as much evaporation area as possible while preventing solar heat from being used to heat excess water. The rate of solar steam generation can reach up to 2.40 kg m^?2 h^?1 under solar illumination of 1 kW m^?2, among the best values reported. In addition, solar thermal efficiency approaching 100 % is achieved. This work enhances solar water‐evaporation performance and promotes the application of solar‐driven evaporation systems made of carbon‐based materials.     

Cover Picture: Electrochemical Oxidative Csp3—H/S—H Cross‐Coupling with Hydrogen Evolution for Synthesis of Tetrasubstituted Olefins (Chin. J. Chem. 6/2019)

The inside cover picture shows an electrochemical oxidative Csp³‐H/S‐H activation with hydrogen evolution for the synthesis of tetrasubstituted olefins. This method features very high atom economy, besides hydrogen gas, under the base‐free, transition met‐al‐free, and oxidants‐free conditions, no other by‐products were generated. More details are discussed in the article by Lei et al. on page 547–551.

     

A Polypyridyl‐Based Layered Complex as Dual‐Functional Co‐catalyst for Photo‐Driven Organic Dyes Degradation and Water Splitting

With the ever‐increasing concerns on environmental pollution and energy crisis, it is of great urgency to develop high‐performance photocatalyst to eliminate organic pollutants from wastewater and produce hydrogen via water splitting. Herein, a polypyridyl‐based mixed covalent Cu^I/II complex with triangular {Cu₃} and rhombic {Cu₂Cl₄} subunits alternately extended by mixed SCN^– and Cl^– heterobridges [Cu₄(DNP)(SCN)Cl₄]_n ( 1 ) [DNP = 2,6‐bis(1,8‐naphthyridine‐2‐yl)pyridine] was solvothermally synthesized and employed as a dual‐functional co‐photocatalyst. Resulting from a narrowed band‐gap of 1.07 eV with suitable redox potential and unsaturated Cu^I/II sites, the complex together with H₂O₂ can effectively degrade Rhodamine B and methyl orange up to 87.4 and 88.2 %, respectively. Meanwhile, the complex mixed with H₂PtCl₆ can also accelerate the photocatalytic water splitting in the absence of a photosensitizer with the hydrogen production rate of 27.5 μmol · g^–1 · h^–1. These interesting findings may provide informative hints for the design of the multiple responsive photocatalysts.     

Precisely Controlled Delivery of Abaloparatide through Injectable Hydrogel to Promote Bone Regeneration

Side‐effects from allograft, limited bone stock, and site morbidity from autograft are the major challenges to traditional bone defect treatments. With the advance of tissue engineering, hydrogel injection therapy is introduced as an alternative treatment. Therapeutic drugs and growth factors can be carried by hydrogels and delivered to patients. Abaloparatide, as an analog of human recombinant parathyroid hormone protein (PTHrp) and an alternative to teriparatide, has been considered as a drug for treating postmenopausal osteoporosis since 2017. Since only limited cases of receiving abaloparatide with polymeric scaffolds have been reported, the effects of abaloparatide on pre‐osteoblast MC3T3‐E1 are investigated in this study. It is found that in vitro abaloparatide treatment can promote pre‐osteoblast MC3T3‐E1 cells’ viability, differentiation, and mineralization significantly. For the drug delivery system, 3D porous structure of the methacrylated gelatin (GelMA) hydrogel is found effective for prolonging the release of abaloparatide (more than 10 days). Therefore, injectable photo‐crosslinked GelMA hydrogel is used in this study to prolong the release of abaloparatide and to promote healing of defected bones in rats. Overall, data collected in this study show no contradiction and imply that Abaloparatide‐loaded GelMA hydrogel is effective in stimulating bone regeneration.     

基于半刚性双(噻唑基苯并咪唑)和不同羧酸的五个一维配合物的合成和表征

通过水热或溶剂热合成的方法制备了5个一维配合物{[Zn(btbb)_(0.5)(m-phda)]·0.5H_2O}_n(1),{[Cd_2(btbb)(adtda)_2(H_2O)]·H_2O}_n(2),[Mn_2(btbb)(tbi)_2]_n(3),{[Cd(btbb)_(0.5)(3-Nitro-o-bdc)(H_2O)]·H_2O}_n(4)和[Cd_2(btbb)(tbi)_2]_n(5)(btbb=1,4-双(2-(4-噻唑基)苯并咪唑-1-基甲基)苯,m-H_2phda=间苯二甲酸,H_2adtda=1,3-金刚烷二羧酸,H_2tbi=5-叔丁基间苯二甲酸,3-Nitro-o-H_2bdc=3-硝基-1,2-苯二甲酸)。配合物1是一个包含22元环的一维链。配合物2是一个包含8元环的一维链,并且氮配体在这个一维链中仅仅起到装饰作用。配合物3是一个一维双链结构。配合物4是一个包含14元环的一维链。配合物5是一个阶梯状的一维双链结构。