Regulating the conductance of tungsten diselenide by oxygen plasma and improving its electrical stability by encapsulation

Two-dimensional(2D)tungsten selenide(WSe_(2))is promising candidate material for future electronic applications,owing to its potential for ultimate device scaling.For improving the electronic performance of WSe_(2)-based field-effect transistors(FETs),the modification of surface properties is essential.In this study,the seamless structural phase transition in WSe_(2) lattice is achieved by soft oxygen plasma,regulating the electrical conductance of WSe_(2)-based FETs.We found that during the soft oxygen plasma treatment with optimal processing time,the generated oxygen ions can substitute some selenium atoms and thus locally modify the bond length,inducing 2H→1T phase transition in WSe_(2) with seamless interfaces.The mosaic structures have been proven to tailor the electronic structure and increase the hole carrier concentration inside WSe_(2),significantly increasing the channel conductance of WSe_(2) FETs.With the further increase of the oxygen plasma treatment time,the creation of more selenium vacancy defects leads to the electronic doping,resulting in the reduction of conductance.Benefiting from the hexagonal boron nitride(h-BN)encapsulation to interrupt the partial structural relaxation from 1T to 2H phase,our WSe_(2) FET exhibits high electronic stability with conductance of 6.8×10^(-4) S,which is about four orders of magnitude higher than 2H WSe_(2)(5.8×10^(-8) S).This study could further broaden the WSe_(2) FETs in applications for functionalization and integration in electronics.

High-volumetric-capacity WSe2 Anode for Potassium-ion Batteries

Exploring high-capacity electrode materials is critical for the development of K-ion batteries.In this work,we report a layered-structured tungsten selenide(WSe2)anode,which not only delivers an ultrahigh volumetric capacity of 1772.8 Ah/L(or 188.4 mAh/g)at a current density of 5 mA/g but also exhibits good rate capability(72 mAh/g at 200 mA/g)and cycling stability(83.14%capacity retention over 100 cycles at 100 mA/g).We have also revealed the underlying reaction mechanism through ex situ X-ray powder diffraction.Furthermore,proof-of-concept full-cell batteries comprising of WSe2 anodes and Prussian Blue cathodes are capable of delivering an energy density of 135.2 Wh/kgcathode+anode.This work highlights the potential of WSe2 as a promising high-volumetric-capacity anode material for rechargeable potassium-ion batteries.