Physical Properties and Hydration of Cementitious Materials Prepared from Vanadium Slag and Phosphate Slag

The physical properties and hydration of a cementitious material, which prepared mainly from the vanadium slag and phosphate slag, were investigated. These slags were investigated can be reused as original resources to prepare cement clinker based on the fact that they mainly comprise silicon and calcium phases, respectively. In this research, a batch of cement having various grades was prepared by mixing the clinker with gypsum, tailings, and fly ash. X-ray diffraction(XRD), differential thermogravimetric(DTG) as well as scanning electron microscopy(SEM) were applied to test and analyze the physical properties and hydration of the prepared cement. Experimental results suggest that the performances of the cement meet the requirements of national standards in all aspects. Its hydration process is similar to that of common Portland cement, whose hydrates were mainly composed of C-S-H, ettringite and CH. Moreover, the addition of fine particles would accelerate cement hydration, as it provided additional surfaces to help the nucleating and growing of hydrates.

Surface group directed low-temperature synthesis and self-assembly of Al nanostructures for lithium storage

Nanostructured aluminum recently delivers a variety of new applications of the earth-abundant Al resource due to the unique properties,but its controllable synthesis remains very challenging with harsh conditions and spontaneously flammable precursors.Herein,a surface group directed method is developed to efficiently achieve low-temperature synthesis and selfassembly of zero-dimensional(0D)Al nanocrystals over one-dimensional(1D)carbon fibers(Al@CFs)through non-flammable AlCl3 reduction at 70°C.Theoretical calculations unveil surface‒OLi groups of carbon fibers exert efficient binding effect to AlCl3,which guides intimate adsorption and in-situ self-assembly of the generated Al nanocrystals.The distinctive 0D-over-1D Al@CFs provides long 1D conductive networks for electron transfer,ultrafine 0D Al nanocrystals for fast lithiation and excellent buffering effect for volume change,thus exhibiting high structure stability and superior lithium storage performance.This work paves the way for mild and controllable synthesis of Al-based nanomaterials for new high-value applications.

Ultrafine Sn_(4)P_(3)nanocrystals from chloride reduction on mechanically activated Na surface for sodium/lithium ion batteries

Nanostructured metal phosphides are very attractive materials in energy storage and conversion,but their applications are severely limited by complicated preparation steps,harsh conditions and large excess of highly toxic phosphorus source.Here we develop a highly efficient one-step method to synthesize Sn_(4)P_(3)nanostructure based on simultaneous reduction of SnCl_(4)and PCl_(3)on mechanically activated Na surface and in situ phosphorization.The low-toxic PCl3 displays a very high phosphorizing efficiency(100%).Furthermore,this simple method is powerful to control phosphide size.Ultrafine Sn_(4)P_(3)nanocrystals(<5 nm)supported on carbon sheets(Sn_(4)P_(3)/C)are obtained,which is due to the unique bottom-up surface-limited reaction.As the anode material for sodium/lithium ion batteries(SIBs/LIBs),the Sn_(4)P_(3)/C shows profound sodiation/lithiation extents,good phase-conversion reversibility,excellent rate performance and long cycling stability,retaining high capacities of 420 mAh/g for SIBs and 760 mAh/g for LIBs even after 400 cycles at 1.0 A/g.Combining simple and efficient preparation,low-toxic and high-efficiency phosphorus source and good control of nanosize,this method is very promising for low-cost and scalable preparation of high-performance Sn_(4)P_(3)anode.

Cu-Ni催化剂助力高效电化学反硝化合成氨

工业化的快速发展破坏了全球氮循环平衡,导致地下水中硝酸盐含量迅速增加.电催化硝酸根还原(ECNR)可以有效地将硝酸盐转化为氨,同步实现硝酸盐去除和氨的合成.然而反硝化合成氨过程步骤复杂且动力学缓慢,因此高效的硝酸盐还原为氨仍面临挑战.本文报道了一种基于电化学沉积方法制备的Cu-Ni合金,可实现稳定、高效的硝态氮向氨氮转化,硝态氮的还原率和氨氮的选择性在四小时内分别达到83.87%和93.6%.根据质子耦合-电子转移理论,通过调节电解液酸碱度pH和加载电势Eh可得到最佳反应条件.研究表明Ni的引入有利于催化剂d带中心的上移,促进硝酸盐和相应中间体的吸附.另外,本文采用旋转圆盘电极和原位傅里叶变换红外光谱技术揭示了硝酸盐制氨过程的反应中间体演化和反应机理.本研究为理解双金属脱硝的协同机理提供了新思路,并提出了硝酸盐在双金属催化剂上的反应路径.