Structural and electronic properties of two-dimensional hydrogenated Xenes

Structural and electronic properties of pristine two-dimensional group IV Xenes (X  =  C, Si, Ge, Sn, Pb) and hydrogenated Xenes are studied, using density functional theory (DFT) calculations with and without spin-orbit coupling (SOC). The pristine hexagonal monolayer Xenes show buckled structure upon relaxation except graphene. The buckling [Formula: see text] increases linearly from graphene to plumbene. The band structures without SOC of group-IV Xenes are semi-metallic. However, inclusion of SOC mainly opens the bandgap at the Dirac point. Semi hydrogenation leads to enhanced buckling in all Xenes which indicate a tendency towards more sp ³ like structures. The electronic structures of semi hydrogenated Xenes do not show Dirac cones. Spin polarized band structures show magnetism with magnetic moment of 1.0 [Formula: see text] and all SH Xenes are magnetic semiconductor except SH plumbene. Full hydrogenation vanishes buckling upon relaxation and the structure becomes planar implying sp ²-like hybridization. The band structures for fully hydrogenated Xenes turns out to be semiconducting and the Dirac cones also disappear. The bandgap changes from indirect to direct at FH stanene, while FH plumbene turns out to be semi-metallic. SOC gives rise to bandgap of 0.47 eV in FH plumbene, which is otherwise a semi-metal.

Role of lone pair electrons in n-type thermoelectric properties of tin oxides

Oxide materials have shown promising thermoelectric applications due to their availability, tunability, and thermal stability. Among oxide materials, the layered tin oxides (SnO) attract raising attention in the electronic and optoelectronic field owing to their lone pair electrons. We have investigated the thermoelectric properties of layered SnO structures through first-principle calculations. SnO exhibits superior n-type thermoelectric properties and the metallicity of SnO becomes stronger with the number of layers increasing. The lone pair electrons around Sn atoms are the key factor to n-type properties and they will get bonded and anti-bonded in the case of interlayer interaction. Monolayer SnO exhibits the best thermoelectric performances and the average n-type ZT value of monolayer SnO can achieve 0.90 at 500-700 K. Our results demonstrate that layered SnO will be the potential n-type two-dimensional oxide thermoelectric material.

Electrospun Janus-like pellicle displays coinstantaneous tri-function of aeolotropic conduction, magnetism and luminescence

A new Janus-like pellicle with top-bottom structure, functionalized by conductive aeolotropism, magnetism and luminescence (defined as a CML Janus-like pellicle), is conceived and constructed via electrospinning by combining microcosmic with macroscopic partitions. [PANI/PMMA]//[Eu(BA)₃phen/PMMA] and [Fe₃O₄/PMMA]//[Tb(BA)₃phen/PMMA] Janus-like microribbons are selected as building units to construct a conductive aeolotropism-luminescence layer (CL layer) and magnetism-luminescence layer (ML layer), and the two layers are combined to form a CML Janus-like pellicle. Macroscopic partition is achieved by designing the Janus-like structure of the pellicle, while Janus-like microribbons are used for the microcosmic partition by separating rare earth luminescent compounds from dark-colored magnetic Fe₃O₄ NPs and conductive PANI. The CML Janus-like pellicle has stronger luminescence compared to the contrast samples. The magnetism of the CML Janus-like pellicle can be adjusted by changing the doping amount of Fe₃O₄ NPs. The CML Janus-like pellicle can achieve a strong and variable conductive aeolotropism via changing the doping amount of PANI and the highest conductive aeolotropism ratio can reach ca. 10⁸ times when the PANI content is 70%. Microcosmic and macroscopic partitions are simultaneously integrated into the CML Janus-like pellicle, which results in almost no detrimental mutual influences between the two layers, and the overall performances of the CML Janus-like pellicle are greatly improved.

Janus-like pellicle with conductive aeolotropism, magnetism and luminescence is designed and constructed via electrospinning by combining microcosmic with macroscopic partitions.