Tellurene:An elemental 2D monolayer material beyond its bulk phases without van der Waals layered structures

Due to the quantum confinement effect,atomically thin two-dimensional(2D)monolayer materials possess distinct characteristics from their corresponding bulk materials,which have received wide attention from science and industry.Among all the 2D materials,elemental 2D materials with the simplest components are most striking.As an emerging group-VIA elemental 2D monolayer material,tellurene exhibits many exciting fundamental properties,such as chemical and mechanical stabilities,bandgap and high carrier mobilities compared to phosphorene,graphene and MoS2,respectively.Besides,in further exploration,it was found that tellurene or tellurene-based device presents excellent thermoelectric properties,piezoelectric properties,quantum Hall effects,and superb optical properties especially nonlinear optics characteristics,etc.The properties of tellurene can be modulated by virtue of strain,defects,edges,and heterojunction effects.In view of so many unique properties,it has drawn significant interest since tellurene was predicted and fabricated successfully in 2017.In this paper,we review the 2D tellurene allotropes,experimental preparation,excellent properties,performance modulation and future development.

A critical review of the interactions between rhizosphere and biochar during the remediation of metal(loid)contaminated soils

Biochar has a large specific surface area,well-developed pore structure,abundant surface functional groups,and superior nutrient supply capacity,which is widely available and environmentally friendly with its advantages in waste resource utilization,heavy metal(loid)remediation,and carbon storage.This review focuses on the interactions between biochar(including raw biochar,functional biochar(modified/engineered/designer biochar),and composite biochar)and rhizosphere during the remediation of soil contaminated with heavy metal(loid)s(Pb,As,Cd,Hg,Co,Cu,Ni,Zn,Cr,etc.)and the effects of these interactions on the microbial communities and root exudates(enzymes and low-molecular-weight organic acids(LMWOAs)).In terms of microorganisms,biochar affects the composition,diversity,and structure of microbial communities through the supply of nutrients,provision of microbial colonization sites,immobilization of heavy metal(loid)s,and introduction of exogenous microorganisms.With regard to root exudates,biochar provides electron transfer support between the microorganisms and exudates,regulates the secretion of enzymes to resist the oxidative stress stimulated by heavy metal(loid)s,ameliorates rhizosphere acidification caused by LMWOAs,and promotes the activity of soil enzymes.The roles and mechanisms of biochar on rhizosphere soils are discussed,as well as the challenges of biochar in the remediation of heavy metal(loid)-contaminated soils,and the issues that need to be addressed in future research are foreseen.