Recently discovered bismuth oxychalcogenide(Bi_(2) O_(2) Se) has aroused great interest due to its ultrahigh carrier mobility,tunable band gap and good environmental stability,making it a promising candidate for high-...Recently discovered bismuth oxychalcogenide(Bi_(2) O_(2) Se) has aroused great interest due to its ultrahigh carrier mobility,tunable band gap and good environmental stability,making it a promising candidate for high-performance electronics and optoelectronics.Their synthesis by colloidal approaches represents a cost-effective alternative to well-established chemical vapor deposition methods,and the resulting electronic-grade inks are important for large-area printed or wearable electronics.However,it is still challenging to control the colloidal growth of Bi_(2) O_(2) Se nanosheets in solution in addition to their assembly into high-performance thin films.Here,we report a two-step colloidal synthesis of Bi_(2) O_(2) Se nanosheets by separating the seeding and growth steps,thereby achieving controllable production of nanosheets with a lateral size of 1.4 mm and a thickness of 10 nm at optimized reaction conditions.These Bi_(2) O_(2) Se nanosheets are electrostatically assembled into large-area thin films,from which a photodetector is fabricated with a responsivity of 6.1 A/W and a short response time of 368 ms under the 520-nm laser illumination.The device exhibits fast response to modulations as high as 100 k Hz,along with a à3 dB bandwidth of 1 kHz.This work provides an important understanding of the controlled colloidal synthesis of Bi_(2) O_(2) Se nanosheets,and demonstrates their potential applications in fast photodetectors.展开更多
To achieve environmentally benign energy conversion with the carbon neutrality target via electrochemical reactions, the innovation of electrocatalysts plays a vital role in the enablement of renewable resources. Nowa...To achieve environmentally benign energy conversion with the carbon neutrality target via electrochemical reactions, the innovation of electrocatalysts plays a vital role in the enablement of renewable resources. Nowadays, Pt-based nanocrystals(NCs) have been identified as one class of the most promising candidates to efficiently catalyze both the half-reactions in hydrogen-and hydrocarbonbased fuel cells. Here, we thoroughly discuss the key achievement in developing shape-controlled Pt and Pt-based NCs, and their electrochemical applications in fuel cells. We begin with a mechanistic discussion on how the morphology can be precisely controlled in a colloidal system, followed by highlighting the advanced development of shape-controlled Pt, Pt-alloy, Pt-based core@shell NCs, Pt-based nanocages, and Pt-based intermetallic compounds. We then select some case studies on models of typical reactions(oxygen reduction reaction at the cathode and small molecular oxidation reaction at the anode) that are enhanced by the shape-controlled Pt-based nanocatalysts. Finally, we provide an outlook on the potential challenges of shape-controlled nanocatalysts and envision their perspective with suggestions.展开更多
In this paper,we have interest in the CdSe(cadmium selenide)semiconductor due to their physical and optical properties that depend on their morphology and size,as well as their possible applications in electronic and ...In this paper,we have interest in the CdSe(cadmium selenide)semiconductor due to their physical and optical properties that depend on their morphology and size,as well as their possible applications in electronic and optoelectronic fields,for example,in the fabrication of solar cells or nanotransistors.For this reason,we synthetized nanoparticles of CdSe using the colloidal method,and varied the pH value:8 to 12,to know the effect of pH on the samples.The nanoparticles were characterized using the SEM(scanning electron microscope)and STM(scanning tunneling microscope)to know the morphology and electronic cloud on the surface of the samples.In each case,we found different sizes(from 6 to 11.5 nm)and shapes as filaments(fibbers),bars and spheres of CdSe nanoparticles and the 3D-FFT was obtained too.展开更多
Laser ablation in liquid is a scalable nanoparticle production method with applications in areas like catalysis and biomedicine.Due to laser-liquid interactions,different energy dissipation channels such as absorption...Laser ablation in liquid is a scalable nanoparticle production method with applications in areas like catalysis and biomedicine.Due to laser-liquid interactions,different energy dissipation channels such as absorption by the liquid and scattering at the ablation plume and cavitation bubble lead to reduced laser energy available for nanoparticle production.Ultrashort pulse durations cause unwanted nonlinear effects in the liquid,and for ns pulses,intra-pulse energy deposition attenuation effects are to be expected.However,intermediate pulse durations ranging from hundreds of picoseconds up to one nanosecond have rarely been studied in particular in single-pulse settings.In this study,we explore the pico-to nanosecond pulse duration regimes to find the pulse duration with the highest ablation efficiency.We find that pulse durations around 1-2 ns enable the most efficient laser ablation in liquid since the laser beam shielding by the ablation plume and cavitation bubble sets in only at longer pulse durations.Furthermore,pump-probe microscopy imaging reveals that the plume dynamics in liquids start to differ from plume dynamics in air at about 2 ns after pulse impact.展开更多
Heteronanostructures(HNs)with precise components and interfaces are important for many applications,such as designing efficient and robust solar-to-fuel catalysts via integrating specific semiconductors with favorable...Heteronanostructures(HNs)with precise components and interfaces are important for many applications,such as designing efficient and robust solar-to-fuel catalysts via integrating specific semiconductors with favorable band alignments.However,rationally endowing such features with rigorous framework control remains a synthetic bottleneck.Herein,we report a modular divergent creation of dual-cocatalysts integrated semiconducting sulfide nanotriads(NTds),comprising both isolated Pd_(x)S oxidation(ox)and MoS_(2) reduction(red)domains within each single CdS counterpart,which exhibit superior photocatalytic activity and stability for hydrogen evolution reaction(HER).The stepwise constructed Pd_(x)S_((ox))−CdS−MoS_(2(red)) NTds possess dualinterfaces facilitating continuous charge separation and segregated active sites accelerating redox reactions,respectively,achieving the HER rate up to 9 mmol·h^(−1)·g^(−1),which is about 60 times higher than that of bare CdS,and show no evidence of deactivation after long-term cycling.This design principle and transformation protocol provide predictable retrosynthetic pathways to HNs with increased degree of complexity and more elaborate functionalities that are otherwise inaccessible.展开更多
Metal nanoparticle （NP） co-catalysts on metal oxide semiconductor supports are attracting attention as photocatalysts for a variety of chemical reactions. Related efforts seek to make and use Pt-free catalysts. In t...Metal nanoparticle （NP） co-catalysts on metal oxide semiconductor supports are attracting attention as photocatalysts for a variety of chemical reactions. Related efforts seek to make and use Pt-free catalysts. In this regard, we report here enhanced CH4 formation rates of 25 and 60 μmol·g^-1·h^-1 by photocatalytic CO2 reduction using hitherto unused ZnPd NPs as well as Au and Ru NPs. The NPs are formed by colloidal synthesis and grafted onto short n-type anatase TiO2 nanotube arrays （TNAs）, grown anodically on transparent glass substrates. The interfacial electric fields in the NP-grafted TiO2 nanotubes were probed by ultraviolet photoelectron spectroscopy （UPS）. Au NP-grafted TiO2 nanotubes （Au-TNAs） showed no band bending, but a depletion region was detected in Ru NP-grafted TNAs （Ru-TNAs） and an accumulation layer was observed in ZnPd NP-grafted TNAs （ZnPd-TNAs）. Temperature programmed desorption （TPD） experiments showed significantly greater CO2 adsorption on NP-grafted TNAs. TNAs with grafted NPs exhibit broader and more intense UV-visible absorption bands than bare TNAs. We found that CO2 photoreduction by nanoparticle-grafted TNAs was driven not only by ultraviolet photons with energies greater than the TiO2 band gap, but also by blue photons close to and below the anatase band edge. The enhanced rate of CO2 reduction is attributed to superior use of blue photons in the solar spectrum, excellent reactant adsorption, efficient charge transfer to adsorbates, and low recombination losses.展开更多
基金supported by National Science Foundations of China (Nos.51873088, 12004195)Natural Science Foundations of Tianjin (No.20JCQNJC01820)+2 种基金Tianjin Municipal Science and Technology Commission (No.18JCZDJC38400)“111” Project of China’s Higher Education (No.B18030)Fundamental Research Funds for the Central Universities from Nankai University (No.63201061)。
文摘Recently discovered bismuth oxychalcogenide(Bi_(2) O_(2) Se) has aroused great interest due to its ultrahigh carrier mobility,tunable band gap and good environmental stability,making it a promising candidate for high-performance electronics and optoelectronics.Their synthesis by colloidal approaches represents a cost-effective alternative to well-established chemical vapor deposition methods,and the resulting electronic-grade inks are important for large-area printed or wearable electronics.However,it is still challenging to control the colloidal growth of Bi_(2) O_(2) Se nanosheets in solution in addition to their assembly into high-performance thin films.Here,we report a two-step colloidal synthesis of Bi_(2) O_(2) Se nanosheets by separating the seeding and growth steps,thereby achieving controllable production of nanosheets with a lateral size of 1.4 mm and a thickness of 10 nm at optimized reaction conditions.These Bi_(2) O_(2) Se nanosheets are electrostatically assembled into large-area thin films,from which a photodetector is fabricated with a responsivity of 6.1 A/W and a short response time of 368 ms under the 520-nm laser illumination.The device exhibits fast response to modulations as high as 100 k Hz,along with a à3 dB bandwidth of 1 kHz.This work provides an important understanding of the controlled colloidal synthesis of Bi_(2) O_(2) Se nanosheets,and demonstrates their potential applications in fast photodetectors.
基金supported by the National Science Foundation (DMR 1808383)partially supported by S3IP at the State University of New York at Binghamton。
文摘To achieve environmentally benign energy conversion with the carbon neutrality target via electrochemical reactions, the innovation of electrocatalysts plays a vital role in the enablement of renewable resources. Nowadays, Pt-based nanocrystals(NCs) have been identified as one class of the most promising candidates to efficiently catalyze both the half-reactions in hydrogen-and hydrocarbonbased fuel cells. Here, we thoroughly discuss the key achievement in developing shape-controlled Pt and Pt-based NCs, and their electrochemical applications in fuel cells. We begin with a mechanistic discussion on how the morphology can be precisely controlled in a colloidal system, followed by highlighting the advanced development of shape-controlled Pt, Pt-alloy, Pt-based core@shell NCs, Pt-based nanocages, and Pt-based intermetallic compounds. We then select some case studies on models of typical reactions(oxygen reduction reaction at the cathode and small molecular oxidation reaction at the anode) that are enhanced by the shape-controlled Pt-based nanocatalysts. Finally, we provide an outlook on the potential challenges of shape-controlled nanocatalysts and envision their perspective with suggestions.
文摘In this paper,we have interest in the CdSe(cadmium selenide)semiconductor due to their physical and optical properties that depend on their morphology and size,as well as their possible applications in electronic and optoelectronic fields,for example,in the fabrication of solar cells or nanotransistors.For this reason,we synthetized nanoparticles of CdSe using the colloidal method,and varied the pH value:8 to 12,to know the effect of pH on the samples.The nanoparticles were characterized using the SEM(scanning electron microscope)and STM(scanning tunneling microscope)to know the morphology and electronic cloud on the surface of the samples.In each case,we found different sizes(from 6 to 11.5 nm)and shapes as filaments(fibbers),bars and spheres of CdSe nanoparticles and the 3D-FFT was obtained too.
基金financial supports from the German Research Foundation (DFG) with the projects GO 2566/7-1,GO 2566/10-1,HU 1893/5-1,HU 1893/6-1 and HU 1893/7-1
文摘Laser ablation in liquid is a scalable nanoparticle production method with applications in areas like catalysis and biomedicine.Due to laser-liquid interactions,different energy dissipation channels such as absorption by the liquid and scattering at the ablation plume and cavitation bubble lead to reduced laser energy available for nanoparticle production.Ultrashort pulse durations cause unwanted nonlinear effects in the liquid,and for ns pulses,intra-pulse energy deposition attenuation effects are to be expected.However,intermediate pulse durations ranging from hundreds of picoseconds up to one nanosecond have rarely been studied in particular in single-pulse settings.In this study,we explore the pico-to nanosecond pulse duration regimes to find the pulse duration with the highest ablation efficiency.We find that pulse durations around 1-2 ns enable the most efficient laser ablation in liquid since the laser beam shielding by the ablation plume and cavitation bubble sets in only at longer pulse durations.Furthermore,pump-probe microscopy imaging reveals that the plume dynamics in liquids start to differ from plume dynamics in air at about 2 ns after pulse impact.
基金the National Natural Science Foundation of China(Nos.21431006,U1932213,21905261,and 22171065)the National key Research and Development Program of China(Nos.2018YFE0202201 and 2021YFA0715700)+5 种基金the University Synergy Innovation Program of Anhui Province(No.GXXT-2019-028)the Science and Technology Major Project of Anhui Province(No.201903a05020003)S.K.H.acknowledges the Anhui Province Key Research and Development Plan(No.202104e11020005)the Hefei National Laboratory for Physical Sciences at the Microscale(No.KF2020005).C.G.acknowledges the National Postdoctoral Program for Innovative Talents(No.BX20180284)the China Postdoctoral Science Foundation(No.2019M660155).
文摘Heteronanostructures(HNs)with precise components and interfaces are important for many applications,such as designing efficient and robust solar-to-fuel catalysts via integrating specific semiconductors with favorable band alignments.However,rationally endowing such features with rigorous framework control remains a synthetic bottleneck.Herein,we report a modular divergent creation of dual-cocatalysts integrated semiconducting sulfide nanotriads(NTds),comprising both isolated Pd_(x)S oxidation(ox)and MoS_(2) reduction(red)domains within each single CdS counterpart,which exhibit superior photocatalytic activity and stability for hydrogen evolution reaction(HER).The stepwise constructed Pd_(x)S_((ox))−CdS−MoS_(2(red)) NTds possess dualinterfaces facilitating continuous charge separation and segregated active sites accelerating redox reactions,respectively,achieving the HER rate up to 9 mmol·h^(−1)·g^(−1),which is about 60 times higher than that of bare CdS,and show no evidence of deactivation after long-term cycling.This design principle and transformation protocol provide predictable retrosynthetic pathways to HNs with increased degree of complexity and more elaborate functionalities that are otherwise inaccessible.
文摘Metal nanoparticle （NP） co-catalysts on metal oxide semiconductor supports are attracting attention as photocatalysts for a variety of chemical reactions. Related efforts seek to make and use Pt-free catalysts. In this regard, we report here enhanced CH4 formation rates of 25 and 60 μmol·g^-1·h^-1 by photocatalytic CO2 reduction using hitherto unused ZnPd NPs as well as Au and Ru NPs. The NPs are formed by colloidal synthesis and grafted onto short n-type anatase TiO2 nanotube arrays （TNAs）, grown anodically on transparent glass substrates. The interfacial electric fields in the NP-grafted TiO2 nanotubes were probed by ultraviolet photoelectron spectroscopy （UPS）. Au NP-grafted TiO2 nanotubes （Au-TNAs） showed no band bending, but a depletion region was detected in Ru NP-grafted TNAs （Ru-TNAs） and an accumulation layer was observed in ZnPd NP-grafted TNAs （ZnPd-TNAs）. Temperature programmed desorption （TPD） experiments showed significantly greater CO2 adsorption on NP-grafted TNAs. TNAs with grafted NPs exhibit broader and more intense UV-visible absorption bands than bare TNAs. We found that CO2 photoreduction by nanoparticle-grafted TNAs was driven not only by ultraviolet photons with energies greater than the TiO2 band gap, but also by blue photons close to and below the anatase band edge. The enhanced rate of CO2 reduction is attributed to superior use of blue photons in the solar spectrum, excellent reactant adsorption, efficient charge transfer to adsorbates, and low recombination losses.
