Applications of 2D-Layered Palladium Diselenide and Its van der Waals Heterostructures in Electronics and Optoelectronics

The rapid development of two-dimensional(2D)transition-metal dichalcogenides has been possible owing to their special structures and remarkable properties.In particular,palladium diselenide(PdSe_(2))with a novel pentagonal structure and unique physical characteristics have recently attracted extensive research inter-est.Consequently,tremendous research progress has been achieved regarding the physics,chemistry,and electronics of PdSe_(2).Accordingly,in this review,we recapitulate and summarize the most recent research on PdSe_(2),including its structure,properties,synthesis,and appli-cations.First,a mechanical exfoliation method to obtain PdSe_(2) nanosheets is introduced,and large-area synthesis strate-gies are explained with respect to chemical vapor deposition and metal selenization.Next,the electronic and optoelectronic properties of PdSe_(2) and related hetero-structures,such as field-effect transistors,photodetectors,sensors,and thermoelec-tric devices,are discussed.Subsequently,the integration of systems into infrared image sensors on the basis of PdSe_(2) van der Waals heterostructures is explored.Finally,future opportunities are highlighted to serve as a general guide for physicists,chemists,materials scientists,and engineers.Therefore,this com-prehensive review may shed light on the research conducted by the 2D material community.

Applications of nanogenerators for biomedical engineering and healthcare systems

The dream of human beings for long living has stimulated the rapid development of biomedical and healthcare equipment.However,conventional biomedical and healthcare devices have shortcomings such as short service life,large equipment size,and high potential safety hazards.Indeed,the power supply for conventional implantable device remains predominantly batteries.The emerging nanogenerators,which harvest micro/nanomechanical energy and thermal energy from human beings and convert into electrical energy,provide an ideal solution for self-powering of biomedical devices.The combination of nanogenerators and biomedicine has been accelerating the development of self-powered biomedical equipment.This article first introduces the operating principle of nanogenerators and then reviews the progress of nanogenerators in biomedical applications,including power supply,smart sensing,and effective treatment.Besides,the microbial disinfection and biodegradation performances of nanogenerators have been updated.Next,the protection devices have been discussed such as face mask with air filtering function together with real-time monitoring of human health from the respiration and heat emission.Besides,the nanogenerator devices have been categorized by the types of mechanical energy from human beings,such as the body movement,tissue and organ activities,energy from chemical reactions,and gravitational potential energy.Eventually,the challenges and future opportunities in the applications of nanogenerators are delivered in the conclusive remarks.

High-performance electronics and optoelectronics of monolayer tungsten diselenide full film from pre-seeding strategy

Tungsten diselenide (WSe2) possesses extraordinary electronic properties forapplications in electronics, optoelectronics, and emerging exciton physics. Thesynthesis of monolayer WSe2 film is of topmost for device arrays and integratedcircuits. The monolayer WSe2 film has yet been reported by thermal chemicalvapor deposition (CVD) approach, and the nucleation mechanism remainsunclear. Here, we report a pre-seeding strategy for finely regulating the nucleidensity at an early stage and achieving a fully covered film after chemicalvapor deposition growth. The underlying mechanism is heterogeneous nucle-ation from the pre-seeding tungsten oxide nanoparticles. At first, we optimized the precursor concentration for pre-seeding. Besides, we confirmed the superi-ority of the pre-seeding method, compared with three types of substrate pre-treatments, including nontreatment, sonication in an organic solvent, andoxygen plasma. Eventually, the high-quality synthetic WSe2 monolayer filmexhibits excellent device performance in field-effect transistors and photodetec-tors. We extracted thermodynamic activation energy from the nucleation andgrowth data. Our results may shed light on the wafer-scale production ofhomogeneous monolayer films of WSe2, other 2D materials, and their van derWaals heterostructures.

Selective and self-validating breath-level detection of hydrogen sulfide in humid air by gold nanoparticle-functionalized nanotube arrays

We demonstrate the selective detection of hydrogen sulfide at breath concentration levels under humid airflow,using a self-validating 64-channel sensor array based on semiconducting single-walled carbon nanotubes(sc-SWCNTs).The reproducible sensor fabrication process is based on a multiplexed and controlled dielectrophoretic deposition of sc-SWCNTs.The sensing area is functionalized with gold nanoparticles to address the detection at room temperature by exploiting the affinity between gold and sulfur atoms of the gas.Sensing devices functionalized with an optimized distribution of nanoparticles show a sensitivity of 0.122%/part per billion(ppb)and a calculated limit of detection(LOD)of 3 ppb.Beyond the self-validation,our sensors show increased stability and higher response levels compared to some commercially available electrochemical sensors.The cross-sensitivity to breath gases NH3 and NO is addressed demonstrating the high selectivity to H2S.Finally,mathematical models of sensors’electrical characteristics and sensing responses are developed to enhance the differentiation capabilities of the platform to be used in breath analysis applications.

Biofunctionalized all-polymer photonic lab on a chip with integrated solid-state light emitter

A photonic lab on a chip(PhLOC),comprising a solid-state light emitter(SSLE)aligned with a biofunctionalized optofluidic multiple internal reflection(MIR)system,is presented.The SSLE is obtained by filling a microfluidic structure with a phenyltrimethoxysilane(PhTMOS)aqueous sol solution containing a fluorophore organic dye.After curing,the resulting xerogel solid structure retains the emitting properties of the fluorophore,which is evenly distributed in the xerogel matrix.Photostability studies demonstrate that after a total dose(at λ5365 nm)greater than 24 J cm^(-2),the xerogel emission decay is only 4.1%.To re-direct the emitted light,the SSLE includes two sets of air mirrors that surround the xerogel.Emission mapping of the SSLE demonstrates that alignment variations of 150 mm(between the SSLE and the external pumping light source)provide fluctuations in emitted light smaller than 5%.After this verification,the SSLE is monolithically implemented with a MIR,forming the PhLOC.Its performance is assessed by measuring quinolone yellow,obtaining a limit of detection(LOD)of(0.6060.01)mM.Finally,the MIR is selectively biofunctionalized with horseradish peroxidase(HRP)for the detection of hydrogen peroxide(H_(2)O_(2))target analyte,obtaining a LOD of(0.760.1)μM for H_(2)O_(2),confirming,for the first time,that solid-state xerogel-based emitters can be massively implemented in biofunctionalized PhLOCs.