Modified TiO_(2)/In_(2)O_(3) heterojunction with efficient charge separation for visible-light-driven photocatalytic CO_(2) reduction to C_(2) product

Utilizing sunlight to convert CO_(2) into chemical fuels could address the greenhouse effect and fossil fuel crisis,Heterojunction structure catalysts with oxygen vacancy are attractive in the field of photocatalytic CO_(2) conversion.Herein,a modified TiO_(2)/In_(2)O_(3)(R-P2 5/In_(2)O_(3-x)) type Ⅱ heterojunction composite with oxygen vacancies is designed for photocatalytic CO_(2) reduction,which exhibits excellent CO_(2) reduction activity,with a C_(2) selectivity of 56.66%(in terms of R_(electron)).In situ Fourier-transform infrared spectroscopy(DRIFTS) and time-resolved photoluminescence(TR-PL) spectroscopy are used to reveal the intermediate formation of the photocatalytic mechanism and photogenerated electron lifetime,respectively.The experimental characterizations reveal that the R-P25/In_(2)O_(3-x) composite shows a remarkable behavior for coupling C-C bonds.Besides,efficient charge separation contributes to the improved CO_(2) conversion performance of photocatalysts.This work introduces a type Ⅱ heterojunction composite photocatalyst,which promotes understanding the CO_(2) reduction mechanisms on heterojunction composites and is valuable for the development of photocatalysts.

Highly enhanced UV absorption and light emission of monolayer WS_(2)through hybridization with Ti_(2)N MXene quantum dots and g-C_(3)N_(4)quantum dots

Two-dimensional(2D)transition metal dichalcogenides(TMD)are atomically thin semiconductors with promising optoelectronic applications across the visible spectrum.However,their intrinsically weak light absorption and the low photoluminescence quantum yield(PLQY)restrict their performance and potential use,especially in ultraviolet(UV)wavelength light ranges.Quantum dots(QD)derived from 2D materials(2D/QD)provide efficient light absorption and emission of which energy can be tuned for desirable light wavelength.In this study,we greatly enhanced the photon absorption and PLQY of monolayer(1L)tungsten disulfide(WS_(2))in the UV range via hybridization with 2D/QD,particularly titanium nitride MXene QD(Ti_(2)N MQD)and graphitic carbon nitride QD(GCNQD).With the hybridization of MQD or GCNQD,1LWS_(2)showed a maximum PL enhancement by 15 times with 300 nm wavelength excitation,while no noticeable enhancement was observed when the excitation photon energy was less than the bandgap of the QD,indicating that UV absorption by the QD played a crucial role in enhancing the light emission of 1L-WS_(2)in our 0D/2D hybrid system.Our findings present a convenient method for enhancing the photo-response of 1L-WS_(2)to UV light and offer exciting possibilities for harvesting UV energy using 1L-TMD.

Light-emitting MXene quantum dots

MXene(M_(n+1)Xn)is an emerging class of layered two-dimensional(2D)materials,which are derived from their bulk-state MAX phase(M_(n+1)AXn,where M:early transition metal,A:group element 13 and 14,and X:carbon and/or nitrogen).MXenes have found wide-ranging applications in energy storage devices,sensors,catalysis,etc.owing to their high electronic conductivity and wide range of optical absorption.However,the absence of semiconducting MXenes has limited their applications related to light emission.Research has shown that quantum dots(QDs)derived from MXene(MQDs)not only retain the properties of the parent MXene but also demonstrate significant improvement on light emission and quantum yield(QY).The optical properties and photoluminescence(PL)emission mechanisms of these light-emitting MQDs have not been comprehensively investigated.Recently,work on light-emitting MQDs has shown good progress,and MQDs exhibiting multi-color PL emission along with high QY have been fabricated.The synthesis methods also play a vital role in determining the light emission properties of these MQDs.This review provides an overview of light-emitting MQDs and their synthesis methods,optical properties,and applications in various optical,sensory,and imaging devices.The future prospects of light-emitting MQDs are also discussed to provide an insight that helps to further advance the progress on MQDs.

Significant enhancement of photoresponsive characteristics and mobility of MoS2-based transistors through hybridization with perovskite CsPbBr3 quantum dots

Inorganic perovskite CsPbBr3 quantum dots (QDs) are potential nanoscale photosensitizers;moreover,two-dimensional (2-D) molybdenum disulfide (MoS2) has been intensively studied for application in the active layers of optoelectronic devices.In this study,heterostructures of 2D-monolayered MoS2 with zero-dimensional functionalized CsPbBr3 QDs were prepared,and their nanoscale optical characteristics were investigated.The effect of n-type doping on the MoS2 monolayer after hybridization with perovskite CsPbBr3 QDs was observed using laser confocal microscope photoluminescenca (PL) and Raman spectra.Field-effect transistors (FETs) using MoS2 and the MoS2-CsPbBr3 QDs hybrid were also fabricated,and their electrical and photoresponsive characteristics were investigated in terms of the charge transfer effect.For the MoS2-CsPbBr3 QDs-based FETs,the field effect mobility and photoresponsivity upon light irradiation were enhanced by ~ 4 times and a dramatic ~ 17 times,respectively,compared to the FET prepared without the parovskite QDs and without light irradiation.It is noteworthy that the photoresponsivity of the MoS-2-CsPbBr3 QDs-based FETs significantly increased with increasing light power,which is completely contrary to the behavior observed in previous studies of MoS2-based FETs.The increased mobility and significant enhancement of the photoresponsivity can be attributed to the n-type doping effect and efficient energy transfer from CsPbBr3 QDs to MoS2.The results indicate that the optoelectronic characteristics of MoS2-based FETs can be significantly improved through hybridization with photosensitive parovskite CsPbBr3 QDs.

Enhancement of photoresponsive electrical characteristics of multilayer MoS2 transistors using rubrene patches

Multilayer MoS2 is a promising active material for sensing, energy harvesting, and optoelectronic devices owing to its intriguing tunable electronic band structure. However, its optoelectronic applications have been limited due to its indirect band gap nature. In this study, we fabricated a new type of phototransistor using multilayer MoS2 crystal hybridized with p-type organic semiconducting rubrene patches. Owing to the outstanding photophysical properties of rubrene, the device characteristics such as charge mobility and photoresponsivity were considerably enhanced to an extent depending on the thickness of the rubrene patches. The enhanced photoresponsive conductance was analyzed in terms of the charge results of the nanoscale laser confocal time-resolved PL measurements. transfer doping effect, validated by the microscope photoluminescence （PL） and