The extraordinary optical and electronic properties of anisotropic two-dimensional materials,such as black phosphorus,ReS2,and GeSe,enable them a promising component of polarization-sensitive photodetectors.However,th...The extraordinary optical and electronic properties of anisotropic two-dimensional materials,such as black phosphorus,ReS2,and GeSe,enable them a promising component of polarization-sensitive photodetectors.However,these applications are significantly limited by the challenges of air-stability,response time,and linearly dichroic ratio.Interestingly,palladium diselenide(PdSe2)with high air stability is an emerging material that has robust in-plane anisotropy induced by its asymmetric pentagonal lattice structure.We have successfully prepared a few-layer PdSe2 using micromechanical exfoliation,and here we demonstrate the strong linear dichroism behavior of PdSe2 by polarization-resolved absorption spectra measurements.Such unique linear dichroism,endows the PdSe2 photodetector powerful ability to detect polarized light.The photodetector based on 5L PdSe2,as tested with polarization-dependent photocurrent mapping,exhibited competitive capability to detect polarized light,achieving a significant photocurrent on/off ratio(>10^2),the quite fast response time(<11 ms)and robust linearly dichroic ratios(/max//min≈1.9 at 532 nm).These results are essential advance in the development of polarization-sensitive photodetector,a crucial step towards opening up a new avenue for the application of 2D optoelectronic devices.展开更多
Palladium diselenide(PdSe2),a stable layered material with pentagonal structure,has attracted extensive interest due to its excellent electrical and optoelectronic performance.Here,we report a reliable process to synt...Palladium diselenide(PdSe2),a stable layered material with pentagonal structure,has attracted extensive interest due to its excellent electrical and optoelectronic performance.Here,we report a reliable process to synthesize PdSe2 via chemical vapor deposition(CVD)method.Through systematic regulation of temperature in the growth process,we can tune the thickness,size,nucleation density and morphology of PdSe2 nanosheets.Field-effect transistors based on PdSe2 nanosheets exhibit n-type behavior and present a high electron mobility of 105 cm^2·V^−1·s^−1.The electrical property of the devices after 6 months keeping in the air show little change,implying outstanding air-stability of PdSe2.In addition,PdSe2 near-infrared photodetector shows a photoresponsivity of 660 A·W^−1 under 914 nm laser.These performances are better than those of most CVD-grown 2D materials,making ultrathin PdSe2 a highly qualified candidate material for next-generation optoelectronic applications.展开更多
By combining structural search and first-principles calculations,we predict a new stable twodimensional PdSe monolayer,and systematically investigate its structural,electronic and optical properties.The calculated for...By combining structural search and first-principles calculations,we predict a new stable twodimensional PdSe monolayer,and systematically investigate its structural,electronic and optical properties.The calculated formation enthalpy,phonon spectra and molecular dynamic simulations confirm that PdSe monolayer possesses excellent thermodynamic and dynamic stability.PdSe monolayer is a semiconductor with an indirect band gap of∼1.10 eV.The carrier transport of PdSe monolayer is dominated by hole and exhibits remarkable anisotropy due to the intrinsic structure anisotropy.The optical properties also show obvious anisotropic characteristic with considerable absorption coefficient and broad absorption from the visible to ultraviolet regions.Benefiting from these excellent physical properties,PdSe monolayer is expected to be a promising candidate as electronic and optoelectronic devices.展开更多
The extraction experiments of chromium（W） from aqueous waste solution by predispersed solvent extraction （PDSE） process with extractant （HEHPEHE） and its mixture, including acidic extractant （D2EHPA）, alkaline...The extraction experiments of chromium（W） from aqueous waste solution by predispersed solvent extraction （PDSE） process with extractant （HEHPEHE） and its mixture, including acidic extractant （D2EHPA）, alkaline extractant （TOA） and neutral extractant （TBP） were carried out respectively. It is found that the extractant HEHPEHE exhibited high extraction selectivity to chromium（III） from aqueous waste solution. The colloidal liquid aphrons （CLAs） were successfully generated using kerosene as a solvent, HEHPEHE as an extractant, sodium dodecyl benzene sulphate （SDBS） as a surfactant in aqueous phase and polyoxyethylene sorbitol anhydride monolaurate （Tween-20） in oil phase. To study the extraction efficiency and advantages of the PDSE process in the removal of chromium（III）, the effects of major factors, such as initial chromium（III） concentration, volume of colloidal gas aphrons （CGAs）, HEHPEHE volume fraction, phase ratio （solvent phase to water phase）, mass fraction of dodecyl trimethylammonium bromide （HTAB）, mass fraction of SDBS, mass fraction of Tween-20 and initial pH of aqueous waste solution were also investigated and the appropriate process conditions were obtained. Under the appropriate conditions, the extraction efficiency of chromium（III） above 99.9 % can be achieved and the treated aqueous waste solution can be discharged directly without polluting the environment.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.61775241)Youth Innovation Team(No.2019012)+3 种基金of CSU,Hunan province key research and development project(No.2019GK2233)the Science and Technology Innovation Basic Research Project of Shenzhen(No.JCYJ20180307151237242)the Project of State Key Laboratory of High-Performance Complex Manufacturing,Central South University(No.ZZYJKT2020-12)Z.W.L.acknowledges the funding support from the Australian Research Council(ARC Discovery Projects,DP180102976).
文摘The extraordinary optical and electronic properties of anisotropic two-dimensional materials,such as black phosphorus,ReS2,and GeSe,enable them a promising component of polarization-sensitive photodetectors.However,these applications are significantly limited by the challenges of air-stability,response time,and linearly dichroic ratio.Interestingly,palladium diselenide(PdSe2)with high air stability is an emerging material that has robust in-plane anisotropy induced by its asymmetric pentagonal lattice structure.We have successfully prepared a few-layer PdSe2 using micromechanical exfoliation,and here we demonstrate the strong linear dichroism behavior of PdSe2 by polarization-resolved absorption spectra measurements.Such unique linear dichroism,endows the PdSe2 photodetector powerful ability to detect polarized light.The photodetector based on 5L PdSe2,as tested with polarization-dependent photocurrent mapping,exhibited competitive capability to detect polarized light,achieving a significant photocurrent on/off ratio(>10^2),the quite fast response time(<11 ms)and robust linearly dichroic ratios(/max//min≈1.9 at 532 nm).These results are essential advance in the development of polarization-sensitive photodetector,a crucial step towards opening up a new avenue for the application of 2D optoelectronic devices.
基金We acknowledge the support from National Natural Science Foundation of China(Nos.61804050,51991340,51991343,and 51872086)the Fundamental Research Funds of the Central Universities(Nos.531107051078 and 531107051055)+2 种基金the Double First-Class Initiative of Hunan University(No.531109100004)the Hunan Key Laboratory of Two-Dimensional Materials(No.2018TP1010)the Strategic Priority Research Program of Chinese Academy of Science,Grant(No.XDB30000000).
文摘Palladium diselenide(PdSe2),a stable layered material with pentagonal structure,has attracted extensive interest due to its excellent electrical and optoelectronic performance.Here,we report a reliable process to synthesize PdSe2 via chemical vapor deposition(CVD)method.Through systematic regulation of temperature in the growth process,we can tune the thickness,size,nucleation density and morphology of PdSe2 nanosheets.Field-effect transistors based on PdSe2 nanosheets exhibit n-type behavior and present a high electron mobility of 105 cm^2·V^−1·s^−1.The electrical property of the devices after 6 months keeping in the air show little change,implying outstanding air-stability of PdSe2.In addition,PdSe2 near-infrared photodetector shows a photoresponsivity of 660 A·W^−1 under 914 nm laser.These performances are better than those of most CVD-grown 2D materials,making ultrathin PdSe2 a highly qualified candidate material for next-generation optoelectronic applications.
基金This work was supported by the National Natural Science Foundation of China with Grant Nos.11604092,11634001,12104385the National Basic Research Programs of China under Grant No.2016YFA0300900The computational resources were provided by the computation platform of National Super-Computer Center in Changsha,China.
文摘By combining structural search and first-principles calculations,we predict a new stable twodimensional PdSe monolayer,and systematically investigate its structural,electronic and optical properties.The calculated formation enthalpy,phonon spectra and molecular dynamic simulations confirm that PdSe monolayer possesses excellent thermodynamic and dynamic stability.PdSe monolayer is a semiconductor with an indirect band gap of∼1.10 eV.The carrier transport of PdSe monolayer is dominated by hole and exhibits remarkable anisotropy due to the intrinsic structure anisotropy.The optical properties also show obvious anisotropic characteristic with considerable absorption coefficient and broad absorption from the visible to ultraviolet regions.Benefiting from these excellent physical properties,PdSe monolayer is expected to be a promising candidate as electronic and optoelectronic devices.
基金Project (NCET-07-0577) supported by New Century Excellent Talents of Ministry of Education, China
文摘The extraction experiments of chromium（W） from aqueous waste solution by predispersed solvent extraction （PDSE） process with extractant （HEHPEHE） and its mixture, including acidic extractant （D2EHPA）, alkaline extractant （TOA） and neutral extractant （TBP） were carried out respectively. It is found that the extractant HEHPEHE exhibited high extraction selectivity to chromium（III） from aqueous waste solution. The colloidal liquid aphrons （CLAs） were successfully generated using kerosene as a solvent, HEHPEHE as an extractant, sodium dodecyl benzene sulphate （SDBS） as a surfactant in aqueous phase and polyoxyethylene sorbitol anhydride monolaurate （Tween-20） in oil phase. To study the extraction efficiency and advantages of the PDSE process in the removal of chromium（III）, the effects of major factors, such as initial chromium（III） concentration, volume of colloidal gas aphrons （CGAs）, HEHPEHE volume fraction, phase ratio （solvent phase to water phase）, mass fraction of dodecyl trimethylammonium bromide （HTAB）, mass fraction of SDBS, mass fraction of Tween-20 and initial pH of aqueous waste solution were also investigated and the appropriate process conditions were obtained. Under the appropriate conditions, the extraction efficiency of chromium（III） above 99.9 % can be achieved and the treated aqueous waste solution can be discharged directly without polluting the environment.
