Interfaces between MoO x and Mo X2(X=S,Se,and Te)

In the past decades there have been many breakthroughs in low-dimensional materials,especially in two-dimensional(2D)atomically thin crystals like graphene.As structural analogues of graphene but with a sizeable band gap,monolayers of atomically thin transition metal dichalcogenides(with formula of MX2,M=Mo,W;X=S,Se,Te,etc.)have emerged as the ideal 2D prototypes for exploring fundamentals in physics such as valleytronics due to the quantum confinement effects,and for engineering a wide range of nanoelectronic,optoelectronic,and photocatalytic applications.Transition metal trioxides as promising materials with low evaporation temperature,high work function,and inertness to air have been widely used in the fabrication and modification of MX2.In this review,we reported the fabrications of one-dimensional MoS2 wrapped MoO2 single crystals with varied crystal direction via atmospheric pressure chemical vapor deposition method and of 2D MoOx covered MoX2 by means of exposing MoX2 to ultraviolet ozone.The prototype devices show good performances.The approaches are common to other transition metal dichalcogenides and transition metal oxides.

Wearable CNT/Ti_(3)C_(2)T_(x)MXene/PDMS composite strain sensor with enhanced stability for real-time human healthcare monitoring

Strain sensors with good stability are vital to the development of wearable healthcare monitoring systems.However,the design of strain sensor with both duration stability and environmental stability is still a challenge.In this work,we propose an ultra-stable and washable strain sensor by embedding a coupled composite film of carbon nanotube(CNT)and Ti_(3)C_(2)T_(x) MXene into polydimethylsiloxane(PDMS)matrix.The composite strain sensor with embedded microstructure and uneven surface makes it conformal to skin,while the CNT/MXene sensing layer exhibits a resistance sensitive to strain.This sensor shows reliable responses at different frequencies and with long-term cycling durability(over 1,000 cycles).Meanwhile,the CNT/MXene/PDMS composite strain sensor provides the advantages of superior anti-interference to temperature change and water washing.The results demonstrate less than 10%resistance changes as the temperature rises from-20 to 80℃or after sonication in water for 120 min,respectively.The composite sensor is applied to monitor human joint motions,such as bending of finger,wrist and elbow.Moreover,the simultaneous monitoring of the electrocardiogram(ECG)signal and joint movement while riding a sports bicycle is demonstrated,enabling the great potential of the as-fabricated sensor in real-time human healthcare monitoring.