Photothermal catalytic CO_(2) conversion provides an effective solution targeting carbon neutrality by synergistic utilization of photon and heat.However,the C-C coupling initiated by photothermal catalysis is still a...Photothermal catalytic CO_(2) conversion provides an effective solution targeting carbon neutrality by synergistic utilization of photon and heat.However,the C-C coupling initiated by photothermal catalysis is still a big challenge.Herein,a three-dimensional(3D)hierarchical W_(18)O_(49)/WTe_(2) hollow nanosphere is constructed through in-situ embodying of oxygen vacancy and tellurium on the scaffold of WO_(3).The light absorption towards near-infrared spectral region and CO_(2) adsorption are enhanced by the formation of half-metal WTe_(2) and the unique hierarchical hollow architecture.Combining with the generation of oxygen vacancy with strengthened CO_(2) capture,the photothermal effect on the samples can be sufficiently exploited for activating the CO_(2) molecules.In particular,the close contact between W_(18)O_(49)and WTe_(2) largely promotes the photoinduced charge separation and mass transfer,and thus the~*CHO intermediate formation and fixedness are facilitated.As a result,the C-C coupling can be evoked between tungsten and tellurium atoms on WTe_(2).The ethylene production by optimized W_(18)O_(49)/WTe_(2) reaches 147.6μmol g^(-1)with the selectivity of 80%.The in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and density functional theory(DFT)calculations are performed to unveil the presence and significance of aldehyde intermediate groups in C-C coupling.The half-metallic WTe_(2) cocatalyst proposes a new approach for efficient CO_(2) conversion with solar energy,and may especially create a new platform for the generation of multi-carbon products.展开更多
We study systematically the negative magnetoresistance(MR)effect in WTe_(2±α)flakes with different thicknesses and doping concentrations.The negative MR is sensitive to the relative orientation between electrica...We study systematically the negative magnetoresistance(MR)effect in WTe_(2±α)flakes with different thicknesses and doping concentrations.The negative MR is sensitive to the relative orientation between electrical-/magnetic-field and crystallographic orientation of WTe_(2±α).The analysis proves that the negative MR originates from chiral anomaly and is anisotropic.Maximum entropy mobility spectrum is used to analyze the electron and hole concentrations in the flake samples.It is found that the negative MR observed in WTe_(2±α)flakes with low doping concentration is small,and the high doping concentration is large.The doping-induced disorder obviously inhibits the positive MR,so the negative MR can be more easily observed.In a word,we introduce disorder to suppress positive MR by doping,and successfully obtain the negative MR in WTe_(2±α)flakes with different thicknesses and doping concentrations,which indicates that the chiral anomaly effect in WTe_(2)is robust.展开更多
Tungsten telluride thin films were successfully prepared on monocrystal sapphire substrates by using atomic layer de-position and chemical vapor deposition technology,and the effects of different tellurization tempera...Tungsten telluride thin films were successfully prepared on monocrystal sapphire substrates by using atomic layer de-position and chemical vapor deposition technology,and the effects of different tellurization temperatures on the properties of tungsten telluride films were investigated.The growth rate,crystal structure and composition of the film samples were character-ized and analyzed by using scanning electron microscope,Raman spectroscopy and X-ray photoelectron spectroscopy.The res-ults showed that tungsten telluride thin films with good crystal orientation in(001)were obtained at telluride temperature of 550℃.When the telluride temperature reached 570℃,the tungsten telluride began to decompose and unsaturated mag-netoresistance was found.展开更多
To improve the performance of solar energy-driven water generation,two-dimensional(2D)photothermal materials requisite to be optimized by some strategies such as alloying,combination of plasmonic and defect modulation...To improve the performance of solar energy-driven water generation,two-dimensional(2D)photothermal materials requisite to be optimized by some strategies such as alloying,combination of plasmonic and defect modulation.However,the challenges faced in practical utilization are the complex preparation process and insufficient solar spectrum absorption.Herein,we propose a strategy of self-enhancing photothermal performance induced by topological surface states(TSSs).2D WTe_(2)is fabricated on the mixed cellulose ester(MCE)for photothermal device.Compared to the MCE and pure water,WTe_(2)@MCE has an excellent photothermal evaporation rate of 1.09 kg·m^(−2)·h^(−1)upon 1 sun irradiation,promoting 6.1 and 3.1 times,respectively.It can be attributed to the characteristics of 2D Weyl semimetal WTe_(2)with TSSs bringing about high optical absorption capacity,low thermal diffusivity,specific heat capacity,and high carrier density,which are strongly proved by experiments and calculation.More importantly,the contribution of TSSs to the enhancement of optical absorption for efficient solar water generation is revealed by the comparative experiment between 2D WTe_(2)with TSSs and that without TSSs.Furthermore,photothermal conversion mechanism is explored in-depth understanding that the photoexcited electrons recombinate with the holes through nonradiative mode for releasing thermal energy by phonons emission via multiple pathway.This work promotes the application of Weyl semimetal material with TSSs in solar water evaporation.展开更多
2D transition metal dichalcogenides(TMDs)have been considered as promising non-precious electrocatalysts for the hydrogen evolution reaction(HER).However,their limited active sites and poor electric conductivity pose ...2D transition metal dichalcogenides(TMDs)have been considered as promising non-precious electrocatalysts for the hydrogen evolution reaction(HER).However,their limited active sites and poor electric conductivity pose a significant hurdle to their HER performance,resulting in a large overpotential.Here,we report the defect engineering in ultrathin tungsten telluride(WTe_(2))nanosheets with semimetal nature to improve hydrogen evolution effectively.We find that the oxygen plasma etching imposes a cutting effect on WTe_(2)nanosheets,resulting in a large number of tungsten vacancies.Particularly,the sample after plasma treatment for 10 min shows a feather-like structure with an overpotential of 251m V at 10 m A/cm~2and a Tafel slope of 94 m V/dec,which is 4 times lower than the Tafel slope of pristine nanosheets.Further first-principles calculations shed light on the evolution of defect-rich WTe_(2)nanosheets and offer rational explanation to their superiority in efficient hydrogen evolution.展开更多
Improving thermal transport between substrate and transistors has become a vital solution to the thermal challenge in nanoelectronics.Recently 2D WTe_(2) has sparked extensive interest because of heavy atomic mass and...Improving thermal transport between substrate and transistors has become a vital solution to the thermal challenge in nanoelectronics.Recently 2D WTe_(2) has sparked extensive interest because of heavy atomic mass and low Debye temperature.Here,the thermal transport of supported WTe_(2) was studied via Raman thermometry with electrical heating.The supported 30 nm WTe2 encased with 70 nm Al_(2)O_(3) delivered 4.8 W·m^(-1)·K^(-1)in-plane thermal conductivity along zigzag direction at room temperature,which was almost 1.6 times larger than that along armchair direction(3.0 W·m^(-1)·K^(-1)).Interestingly,the superior and inferior directions for thermal transport are just opposite of those for electrical transport.Hence,a heat manipulation model in WTe_(2) FET device was proposed.Within the designed configuration,waste heat in WTe_(2) would be mostly dissipated to metal contacts located along zigzag,relieving the local temperature discrepancy in the channel effectively and preventing degradation or breakdown.Our study provides new insight into thermal transport of anisotropic 2D materials,which might inspire energy-efficient nanodevices in the future.展开更多
基金the National Natural Science Foundation of China(51303083)the National Natural Science Foundation of China for Excellent Young Scholars(51922050)+1 种基金the Natural Science Foundation of Jiangsu Province(BK20191293)the Fundamental Research Funds for the Central Universities(30920021123)。
文摘Photothermal catalytic CO_(2) conversion provides an effective solution targeting carbon neutrality by synergistic utilization of photon and heat.However,the C-C coupling initiated by photothermal catalysis is still a big challenge.Herein,a three-dimensional(3D)hierarchical W_(18)O_(49)/WTe_(2) hollow nanosphere is constructed through in-situ embodying of oxygen vacancy and tellurium on the scaffold of WO_(3).The light absorption towards near-infrared spectral region and CO_(2) adsorption are enhanced by the formation of half-metal WTe_(2) and the unique hierarchical hollow architecture.Combining with the generation of oxygen vacancy with strengthened CO_(2) capture,the photothermal effect on the samples can be sufficiently exploited for activating the CO_(2) molecules.In particular,the close contact between W_(18)O_(49)and WTe_(2) largely promotes the photoinduced charge separation and mass transfer,and thus the~*CHO intermediate formation and fixedness are facilitated.As a result,the C-C coupling can be evoked between tungsten and tellurium atoms on WTe_(2).The ethylene production by optimized W_(18)O_(49)/WTe_(2) reaches 147.6μmol g^(-1)with the selectivity of 80%.The in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and density functional theory(DFT)calculations are performed to unveil the presence and significance of aldehyde intermediate groups in C-C coupling.The half-metallic WTe_(2) cocatalyst proposes a new approach for efficient CO_(2) conversion with solar energy,and may especially create a new platform for the generation of multi-carbon products.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.92065110,11674031,11974048,12074334)the National Basic Research Program of China(Grant Nos.2014CB920903 and 2013CB921701)。
文摘We study systematically the negative magnetoresistance(MR)effect in WTe_(2±α)flakes with different thicknesses and doping concentrations.The negative MR is sensitive to the relative orientation between electrical-/magnetic-field and crystallographic orientation of WTe_(2±α).The analysis proves that the negative MR originates from chiral anomaly and is anisotropic.Maximum entropy mobility spectrum is used to analyze the electron and hole concentrations in the flake samples.It is found that the negative MR observed in WTe_(2±α)flakes with low doping concentration is small,and the high doping concentration is large.The doping-induced disorder obviously inhibits the positive MR,so the negative MR can be more easily observed.In a word,we introduce disorder to suppress positive MR by doping,and successfully obtain the negative MR in WTe_(2±α)flakes with different thicknesses and doping concentrations,which indicates that the chiral anomaly effect in WTe_(2)is robust.
基金supported by the National Key Research and Development Program of China(No.2018YFA0704804)Chinese Academy of Sciences Research Instruments and Equipment Development Project(No.ZDKYYQ20220001)。
文摘Tungsten telluride thin films were successfully prepared on monocrystal sapphire substrates by using atomic layer de-position and chemical vapor deposition technology,and the effects of different tellurization temperatures on the properties of tungsten telluride films were investigated.The growth rate,crystal structure and composition of the film samples were character-ized and analyzed by using scanning electron microscope,Raman spectroscopy and X-ray photoelectron spectroscopy.The res-ults showed that tungsten telluride thin films with good crystal orientation in(001)were obtained at telluride temperature of 550℃.When the telluride temperature reached 570℃,the tungsten telluride began to decompose and unsaturated mag-netoresistance was found.
基金supported by the China Postdoctoral Science Foundation(No.2021M691230)the Guangzhou Basic and Applied Basic Research Foundation(No.202202020243)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(Nos.2022A1515110159 and 2023A1515010652)the Fundamental Research Funds for the Central Universities(No.11621019).
文摘To improve the performance of solar energy-driven water generation,two-dimensional(2D)photothermal materials requisite to be optimized by some strategies such as alloying,combination of plasmonic and defect modulation.However,the challenges faced in practical utilization are the complex preparation process and insufficient solar spectrum absorption.Herein,we propose a strategy of self-enhancing photothermal performance induced by topological surface states(TSSs).2D WTe_(2)is fabricated on the mixed cellulose ester(MCE)for photothermal device.Compared to the MCE and pure water,WTe_(2)@MCE has an excellent photothermal evaporation rate of 1.09 kg·m^(−2)·h^(−1)upon 1 sun irradiation,promoting 6.1 and 3.1 times,respectively.It can be attributed to the characteristics of 2D Weyl semimetal WTe_(2)with TSSs bringing about high optical absorption capacity,low thermal diffusivity,specific heat capacity,and high carrier density,which are strongly proved by experiments and calculation.More importantly,the contribution of TSSs to the enhancement of optical absorption for efficient solar water generation is revealed by the comparative experiment between 2D WTe_(2)with TSSs and that without TSSs.Furthermore,photothermal conversion mechanism is explored in-depth understanding that the photoexcited electrons recombinate with the holes through nonradiative mode for releasing thermal energy by phonons emission via multiple pathway.This work promotes the application of Weyl semimetal material with TSSs in solar water evaporation.
基金the National Natural Science Foundation of China(Nos.51728202 and 51909165)the China Postdoctoral Science Foundation(Nos.2020TQ0109 and 2018M630986)+3 种基金the Shenzhen Peacock Plan(No.827-000113)the Science and Technology Planning Project of Guangdong Province(No.2016B050501005)the project Nanotechnology Based Functional Solutions(No.NORTE01-0145-FEDER-000019)Norte Portugal Regional Operational Programme(NORTE2020)under the PORTUGAL 2020。
文摘2D transition metal dichalcogenides(TMDs)have been considered as promising non-precious electrocatalysts for the hydrogen evolution reaction(HER).However,their limited active sites and poor electric conductivity pose a significant hurdle to their HER performance,resulting in a large overpotential.Here,we report the defect engineering in ultrathin tungsten telluride(WTe_(2))nanosheets with semimetal nature to improve hydrogen evolution effectively.We find that the oxygen plasma etching imposes a cutting effect on WTe_(2)nanosheets,resulting in a large number of tungsten vacancies.Particularly,the sample after plasma treatment for 10 min shows a feather-like structure with an overpotential of 251m V at 10 m A/cm~2and a Tafel slope of 94 m V/dec,which is 4 times lower than the Tafel slope of pristine nanosheets.Further first-principles calculations shed light on the evolution of defect-rich WTe_(2)nanosheets and offer rational explanation to their superiority in efficient hydrogen evolution.
基金supported by the National Natural Science Foundation of China(Nos.61801498,11404399,11874423,and 51701237)the National Defense Science and Technology Innovation Zone,the Scientific Researches Foundation of National University of Defense Technology(Nos.ZK18-01-03,ZK18-03-36,ZK20-16,and ZZKY-YX-08-06)+1 种基金the China Postdoctoral Science Foundation(CPSF)(No.2019M663569)the Youth Talent Lifting Project(No.17-JCJQ-QT-004).
文摘Improving thermal transport between substrate and transistors has become a vital solution to the thermal challenge in nanoelectronics.Recently 2D WTe_(2) has sparked extensive interest because of heavy atomic mass and low Debye temperature.Here,the thermal transport of supported WTe_(2) was studied via Raman thermometry with electrical heating.The supported 30 nm WTe2 encased with 70 nm Al_(2)O_(3) delivered 4.8 W·m^(-1)·K^(-1)in-plane thermal conductivity along zigzag direction at room temperature,which was almost 1.6 times larger than that along armchair direction(3.0 W·m^(-1)·K^(-1)).Interestingly,the superior and inferior directions for thermal transport are just opposite of those for electrical transport.Hence,a heat manipulation model in WTe_(2) FET device was proposed.Within the designed configuration,waste heat in WTe_(2) would be mostly dissipated to metal contacts located along zigzag,relieving the local temperature discrepancy in the channel effectively and preventing degradation or breakdown.Our study provides new insight into thermal transport of anisotropic 2D materials,which might inspire energy-efficient nanodevices in the future.
