Large-scale-applicable thermoelectric materials should be both self-sustaining,in order to survive longterm duty cycles,and nonpolluting.Among all classes of known thermoelectric materials,these criteria reduce the av...Large-scale-applicable thermoelectric materials should be both self-sustaining,in order to survive longterm duty cycles,and nonpolluting.Among all classes of known thermoelectric materials,these criteria reduce the available candidate pool,leaving silicon as one of the remaining options.Here we first review the thermoelectric properties of various silicon-related materials with respect to their morphologies and microstructures.We then report the thermoelectric properties of silicon sawing wastes recycled from silicon wafer manufacturing.We obtain a high power factor of~32 mWcm1 K2 at 1273 K with 6%phosphorus substitution in the Si crystal,a value comparable to that of phosphorus-doped silicongermanium alloys.Our work suggests the large-scale thermoelectric applicability of recycled silicon that would otherwise contribute to the millions of tons of industrial waste produced by the semiconductor industry.展开更多
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-S...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.展开更多
The controlled etching of graphite and graphene by catalytic hydrogenation is potentially a key engineering route for the fabrication of graphene nanoribbons with atomic precision.The hydrogenation mechanism,though,re...The controlled etching of graphite and graphene by catalytic hydrogenation is potentially a key engineering route for the fabrication of graphene nanoribbons with atomic precision.The hydrogenation mechanism,though,remains poorly understood.In this study we exploit the benefi ts of aberration-corrected high-resolution transmission electron microscopy to gain insight to the hydrogenation reaction.The etch tracks are found to be commensurate with the graphite lattice.Catalyst particles at the head of an etch channel are shown to be faceted and the angles between facets are multiples of 30°.Thus,the angles between facets are also commensurate with the graphite lattice.In addition,the results of a post-annealing step suggest that all catalyst particles even if they are not involved in etching are actively forming methane during the hydrogenation reaction.Furthermore,the data point against carbon dissolution being a key mechanism during the hydrogenation process.展开更多
基金The work performed at the University of Houston is funded by the U.S.Department of Energy under Grant DE-SC0010831.
文摘Large-scale-applicable thermoelectric materials should be both self-sustaining,in order to survive longterm duty cycles,and nonpolluting.Among all classes of known thermoelectric materials,these criteria reduce the available candidate pool,leaving silicon as one of the remaining options.Here we first review the thermoelectric properties of various silicon-related materials with respect to their morphologies and microstructures.We then report the thermoelectric properties of silicon sawing wastes recycled from silicon wafer manufacturing.We obtain a high power factor of~32 mWcm1 K2 at 1273 K with 6%phosphorus substitution in the Si crystal,a value comparable to that of phosphorus-doped silicongermanium alloys.Our work suggests the large-scale thermoelectric applicability of recycled silicon that would otherwise contribute to the millions of tons of industrial waste produced by the semiconductor industry.
基金the German Federal State of Saxony as part of the“SNIFFBOT:Sniffing Dangerous Gases with Immersive Robots”project under grant agreement number 100369691the German Federal Ministry of Education and Research(No.031B0298)。
文摘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.
文摘The controlled etching of graphite and graphene by catalytic hydrogenation is potentially a key engineering route for the fabrication of graphene nanoribbons with atomic precision.The hydrogenation mechanism,though,remains poorly understood.In this study we exploit the benefi ts of aberration-corrected high-resolution transmission electron microscopy to gain insight to the hydrogenation reaction.The etch tracks are found to be commensurate with the graphite lattice.Catalyst particles at the head of an etch channel are shown to be faceted and the angles between facets are multiples of 30°.Thus,the angles between facets are also commensurate with the graphite lattice.In addition,the results of a post-annealing step suggest that all catalyst particles even if they are not involved in etching are actively forming methane during the hydrogenation reaction.Furthermore,the data point against carbon dissolution being a key mechanism during the hydrogenation process.
