磷化技术研究现状及展望

磷化技术是一项常用的金属表面处理技术,通过金属件表面与酸性磷酸盐溶液产生化学反应,在金属件表面形成一层非金属、非导体的磷酸盐膜(磷化膜)。不同的磷化膜具有防锈、耐磨减摩、润滑、涂漆底层等作用,因此该技术广泛应用于汽车、军工、机械、电器等领域。文章主要介绍了磷化基本原理与常用磷化技术,并给出进一步的研究展望。

Atomic orbitals modulated dual functional bimetallic phosphides derived from MOF on MOF structure for boosting high efficient overall water splitting

The electronic modulation characteristics of efficient metal phosphide electrocatalysts can be utilized to tune the performance of oxygen evolution reaction(OER).However,improving the overall water splitting performance remains a challenging task.By building metal organic framework(MOF)on MOF heterostructures,an efficient strategy for controlling the electrical structure of MOFs was presented in this study.ZIF-67 was in-situ synthesized on MIL-88(Fe)using a two-step self-assembly method,followed by low-temperature phosphorization to ultimately synthesize FeP-CoP_(3)bimetallic phosphides.By combining atomic orbital theory and theoretical calculations(density functional theory),the results reveal the successful modulation of electronic orbitals in FeP-CoP_(3)bimetallic phosphides,which are synthesized from MOF on MOF structure.The synergistic impact of the metal center Co species and the phase conjugation of both kinds of MOFs are responsible for this regulatory phenomenon.Therefore,the catalyst demonstrates excellent properties,demonstrating HER 81 mV(η10)in a 1.0 mol L^(−1)KOH solution and OER 239 mV(η50)low overpotentials.The FeP-CoP_(3)linked dual electrode alkaline batteries,which are bifunctional electrocatalysts,have a good electrocatalytic ability and may last for 50 h.They require just 1.49 V(η50)for total water breakdown.Through this technique,the electrical structure of electrocatalysts may be altered to increase catalytic activity.

First-principles investigation of cohesive energy and electronic structure in vanadium phosphides

First-principles calculations based on the density-functional theory were employed to study the crystal structure of vanadium phosphide compounds,such as V3P,V2P,VP,VP2 and VP4. Cohesive energy of five types of vanadium phosphide compounds was calculated to assess their structural stability. The charge density distribution and densities of states of vanadium phosphides were discussed to study further their electronic structures. The results show that the structure of metal-rich compounds is considerably more stable than the phosphorus-rich compositions,and covalent bond exists between the V and P atoms of V3P,V2P,VP,VP2 and VP4.

High activity and durability of carbon-supported core-shell PtPx@Pt/C catalyst for oxygen reduction reaction

Alloying Pt with transition metals can significantly improve the catalytic properties for the oxygen reduction reaction(ORR).However,the application of Pt-transition metal alloys in fuel cells is largely limited by poor long-term durability because transition metals can easily leach.In this study,we developed a nonmetallic doping approach and prepared a P-doped Pt catalyst with excellent durability for the ORR.Carbon-supported core-shell nanoparticles with a P-doped Pt core and Pt shell(denoted as PtPx@Pt/C)were synthesized via heat-treatment phosphorization of commercial Pt/C,followed by acid etching.Compositional analysis using electron energy loss spectroscopy and X-ray photoelectron spectroscopy clearly demonstrated that Pt was enriched in the near-surface region(approximately 1 nm)of the carbon-supported core-shell nanoparticles.Owning to P doping,the ORR specific activity and mass activity of the PtP_(1.4)@Pt/C catalyst were as high as 0.62 mA cm^(–2)and 0.31 mAμgPt–^(1),respectively,at 0.90 V,and they were enhanced by 2.8 and 2.1 times,respectively,in comparison with the Pt/C catalyst.More importantly,PtP_(1.4)@Pt/C exhibited superior stability with negligible mass activity loss(6%after 30000 potential cycles and 25%after 90000 potential cycles),while Pt/C lost 46%mass activity after 30000 potential cycles.The high ORR activity and durability were mainly attributed to the core-shell nanostructure,the electronic structure effect,and the resistance of Pt nanoparticles against aggregation,which originated from the enhanced ability of the PtP_(1.4)@Pt to anchor to the carbon support.This study provides a new approach for constructing nonmetal-doped Pt-based catalysts with excellent activity and durability for the ORR.

A Novel Scheduling Strategy for Crude Oil Blending

For those refineries which have to deal with different types of crude oil, blending is an attractive solution to obtain a quality feedstock. In this paper, a novel scheduling strategy is proposed for a practical crude oil blending process. The objective is to keep the property of feedstock, mainly described by the true boiling point (TBP) data, consistent and suitable. Firstly, the mathematical model is established. Then, a heuristically initialized hybrid iterative (HIHI) algorithm based on a two-level optimization structure, in which tabu search (TS) and differential evolution (DE) are used for upper-level and lower-level optimization, respectively, is proposed to get the model solution. Finally, the effectiveness and efficiency of the scheduling strategy is validated via real data from a certain refinery.

Two-Dimensional VDW Crystal Sn P3 with High Carrier Mobility and Extraordinary Sunlight Absorbance

Although bulk SnP3 has been fabricated by experiments in the 1970’s,its electronic and optical properties within several layers have not been reported.Here,based on first-principles calculations,we have predicted two-dimensional SnP3 layers as new semiconducting materials that possess indirect band gaps of 0.71 eV(monolayer)and 1.03 eV(bilayer),which are different from the metallic character of bulk structure.Remarkably,2D SnP3 possesses high hole mobility of 9.17×10^4cm^2·V^-1s^-1 and high light absorption(~10^6 cm^-1)in the whole visible spectrum,which predicts 2D SnP3 layers as prospective candidates for nanoelectronics and photovoltaics.Interestingly,we found that 2D SnP3 bilayer shows similar electronic and optical characters of silicon.