A hydrated amorphous iron oxide nanoparticle as active water oxidation catalyst

Developing efficient water oxidation catalysts (WOCs) with earth-abundant elements still remains a challenging task for artificial photosynthesis. Iron-based WOC is a promising candidate because it is economically cheap, little toxic and environmentally friendly. In this study, we found that the catalytic water oxidation activity on amorphous iron-based oxide/hydroxide (FeO_x) can be decreased by an order of magnitude after the dehydration process at room temperature. Thermogravimetric analysis, XRD and Raman results indicated that the dehydration process of FeO_x at room temperature causes the almost completely loss of water molecule with no bulk structural changes. Based on this finding, we prepared hydrated ultrasmall (ca. 2.2 nm) FeO_x nanoparticles of amorphous feature, which turns out to be extremely active as WOC with turnover frequency (TOF) up to 9.3 s^?1 in the photocatalytic Ru(bpy)₃²⁺-Na₂S₂O₈ system. Our findings suggest that future design of active iron-based oxides as WOCs requires the consideration of their hydration status.     

Patterning catalyst via inkjet printing to grow single-walled carbon nanotubes

We demonstrated a method to pattern catalyst via inkjet printing to grow SWNTs, using metal salt solutions as the inks and an ordinary office-use printer. We printed water solutions of cobalt acetate on hydrophilic Si substrates and grew high quality SWNT films.     

Semi-interpenetrating polymer networks toward sulfonated poly(ether ether ketone) membranes for high concentration direct methanol fuel cell

Semi-IPNs were constructed by forming the crosslinking networks via the reaction between BPPO and diamine cross-linkers to overcome the dimensional swelling and methanol-permeation issues of SPEEK.     

A novel carbocatalytic hydride transfer strategy for efficient reduction of structurally different aldehydes and ketones in water

Reduced graphene oxide (rGO)–NaBH₄ is reported as mild and efficient catalyst-system for chemo-/regioselective reduction of structurally different aliphatic, aromatic as well as α,β-unsaturated aldehydes and ketones in water. The rGO was prepared by reducing graphene oxide using Tulsi leaf extract as bio-reductant. Operational simplicity, ambient reaction condition, high yield of pure products (80–97%), no by-product formation, no use of column chromatography for purification are the salient features of the envisaged protocol. Furthermore, the recovered TRGO was recycled and reused for subsequent reductions up to five times without any loss in activity.     

高分散纳米薄水铝石和纳米氧化铝的制备及其对甲基橙的吸附性能

以硝酸铝为铝源,尿素为沉淀剂,采用无模板水热法合成纳米薄水铝石(γ-AlO(OH))。在不同温度下煅烧后,得到氧化铝产物(γ-Al2O_3和θ-Al2O_3)。利用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)、氮气吸附-脱附法和紫外-可见分光光度计(UV-Vis)对产物进行了表征分析。并且研究了产物对甲基橙(MO)的吸附性能,系统地考察了吸附时间、溶液的pH值、甲基橙浓度及循环使用对产物吸附性能的影响。此外,还对吸附过程进行了相关吸附理论研究。结果表明:与其他方法所制备的产物相比,通过该方法获得的产物的分散性更高,形态更均匀和完整。产物为高度分散的纳米捆扎状结构。γ-AlO(OH)对甲基橙的最大吸附量达1 492.5 mg·g~(-1)。另外,产物的吸附机制包含化学作用吸附机制和静电作用吸附机制等。3种产物对甲基橙的吸附均符合Langmuir单分子层吸附模型,吸附过程均符合二级动力学特征。     

三(三甲基硅烷)亚磷酸酯添加剂改善高镍三元正极材料的高电压循环性能

研究了三(三甲基硅烷)亚磷酸酯(TMSP)添加剂对高镍三元正极材料Li Ni_(0.83)Mn_(0.05)Co_(0.12)O_2(LNMC811)高电压循环性能的影响。结合电化学表征、理论计算、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、X射线衍射(XRD)等方法研究发现,在高电位(4.5 Vvs Li/Li~+)下,TMSP添加剂能够在LNMC811正极表面被氧化分解,生成一层富含导锂离子性能好的硅酸盐和电化学稳定的无机碳酸锂,且电解液主要分解产物(有机碳酸锂和氟化锂)含量较少的正极固体电解质界面(CEI)膜;分析表明覆盖在正极表面的薄而均匀的CEI膜,能够很好的降低充放电过程的极化电压,隔离电解液和正极的接触,减少电解液的分解,抑制金属离子的溶出,稳定正极晶体结构,使LNMC811材料能够在4.5 V(vs Li/Li~+)高电压循环时仍然保持良好的循环性能和倍率性能。     

Hydrogenation of 3d-metal oxide clusters: Effects on the structure and magnetic properties

The geometrical structures and properties of the M₈O₁₂, M₈O₁₂H₈, and M₈O₁₂H₁₂ clusters are explored using density functional theory with the generalized gradient approximation for all 3d-metals M from Sc to Zn. It is found that the geometries and total spin magnetic moments of the clusters depended strongly on the 3d-atom type and the hydrogenation extent. More than the half of all of the 30 clusters had singlet lowest total energy states, which could be described as either nonmagnetic or antiferromagnetic. Hydrogenation increases the total spin magnetic moments of the M₈O₁₂H₁₂ clusters when MMn Ni, which become larger by four Bohr magneton than those of the corresponding unary clusters M₈. Hydrogenation substantially affects such properties as polarizability, forbidden band gaps, and dipole moments. Collective superexchange where the local total spin magnetic moments of two atom squads are coupled antiparallel was observed in antiferromagnetic singlet states of Fe₈O₁₂H₈ and Co₈O₁₂H₈, whereas the lowest total energy states of their neighbors Mn₈O₁₂H₈ and Ni₈O₁₂H₈ are ferrimagnetic and ferromagnetic, respectively. Hydrogenation leads to a decrease in the average binding energy per atom when moving across the 3d-metal atom series. © 2018 Wiley Periodicals, Inc.     

Parameter settings in a compact laser-nitriding system for titanium composed of a focused pulsed Nd:YAG laser and nitrogen gas blow

The aim of the present study was to form a nitride layer on a titanium (Ti) substrate through a compact laser-nitriding system comprising a focused pulsed Nd:YAG laser and nitrogen gas blow. To obtain a high-quality layer, the effects of pulse frequency and gas flow rate on the surface characteristics were investigated by using plasma emission analysis as well as X-ray analyses. Optical emission spectra from the laser-induced plasma mainly consisted of ionic Ti lines, and their intensities when the pulse frequency was 15 Hz were much higher than those for 8 Hz. Similarly, the reflections from the δ-TiN phase in the X-ray diffraction (XRD) pattern were enhanced when using 15 Hz. On the other hand, the flow rate of nitrogen gas blow had a significant effect on the thickness of the thin oxide layer that formed above the nitride layer. Using a lower flow rate resulted in the formation of a thicker oxide layer. The higher pulse frequency and the faster flow rate were beneficial for obtaining a higher-quality layer because of the enhancement of nitridation and the suppression of oxidation, respectively.     

A New Application of Carbon Nanotubes Constructing Biosensor

Carbon nanotubes used for constructing biosensor was described for the first time. Single-wall carbon nanotubes (SWNTs) functionalized with carboxylic acid groups were used to immobilize glucose oxidase forming a glucose biosensor. The biosensor response can be determined by amperometric method at a low applied potential (0.40V).     

Thermal Degradation and Flammability Properties of Poly(propylene)/Carbon Nanotube Composites

Nanocomposites based on poly(propylene) and multi‐wall carbon nanotubes (up to 2 vol.‐%) were melt blended, yielding a good dispersion of nanotubes without using any organic treatment or additional additives. Carbon nanotubes are found to significantly enhance the thermal stability of poly(propylene) in nitrogen at high temperatures. Specifically, the nanotube additive greatly reduced the heat release rate of poly(propylene). They are found to be at least as effective a flame‐retardant as clay/poly(propylene) nanocomposites.