Soil contamination by heavy metals has presented severe risks to human health through food chain.As one of the most promising remediation technologies,in-situ immobilization strategy has been widely adopted in practice.However,considering the large quantities of contaminated soil,it is still a huge challenge to design low-cost amendments with strong and long-term immobilization ability.Layered double hydroxides(LDHs)have drawn tremendous attention in fundamental research and practical application because of their unique properties.Moreover,owing to its super-stable mineralization effect to heavy metal ions,LDHs have exhibited great potential in the field of soil remediation.In this work,we mainly focused on the scale production strategy of LDHs with low-cost,and its application in soil remediation.Besides,several key challenges in using LDHs as amendments for immobilization of heavy metal ions are presented.We hope that this mini-review could shed light on the sustainable development of LDHs as amendment for heavy metals in future research directions.
We applied LDHs to modify the bitumen by melt blending, and studied the viscoelasticity of LDHs modifi ed bitumen by means of dynamic shear rheometer(DSR). The creep test was used to evaluate the viscoelastic behavior. The experimental results indicated that, due to the addition of the LDHs, the viscoelastic properties of modifi ed bitumen were superior to those of pristine bitumen. Therefore, the LDHs would be an alternative to modifi ers used in the bitumen to improve the UV-aging resistance during the service of asphalt pavement.
Compared with noble metal catalyst, Co3O4-based electrocatalysts have attracted considerable interesting as low-cost alternatives for oxygen evolution reaction (OER). However, the poor electrocatalytic activity still remains a huge challenge. Herein, we demonstrate a feasible approach through oxidation of CoFe layered double hydroxide (CoFe-LDH) to synthesize Fe-doped Co3O4@C nanopmrticles with size of about 30-50 nm. As OER catalyst, the as-synthesized Fe-doped Co3O4@C nanoparticles exhibited superior OER performance with a small overpotential of 260 mV at the current density of 20 mA cm^-2, a small Tafel slope of 70 mV dec^-1 and long-term durability (there was no obviously OER current density degradation for 100 h) in alkaline solution. The present work opens a new avenue to the exploration of cost-effective and excellent electrocatalysts based on transition metal oxide materials to substitute precious metal materials for water splitting.
Caiyun HeXuzhao HanXianggui KongMeihong JiangDeqiang LeiXiaodong Lei
Polyoxometalates (POMs),a class of discrete anionic metal oxides in groups V and VI,are constructed via the con- densation of metal oxide polyhedral (MOx,M=W^vI,Mo^vI, Vv,Nb,Ta,etc.and x=4-7)with each other in a comer-, edge-,or rarely in a face-sharing manner [1-3].Up to now, the broadening family of POM derivatives ranges from small size clusters to nanoscale giant aggregates,which have shown impressive chemical and physical properties and great potential in fields of catalysis,magnetism,medicine,photochemistry,environment,energy and materials science [4,5].Latest progress on POMs chemistry is directed to the construction of high-nnclearity clusters and the exploration of functional applications in energy chemistry,catalysis,and self-assembly (Figure 1).
Sai AnJian-Cai LiuHuaiying ZhangLifu WuBo QiYu-Fei Song
