Global environmental problems have been increasing with the growth of the world economy and have become a crucial issue.To replace fossil fuels,sustainable and eco-friendly catalysts are required for the removal of or...Global environmental problems have been increasing with the growth of the world economy and have become a crucial issue.To replace fossil fuels,sustainable and eco-friendly catalysts are required for the removal of organic pollutants.In this study,nickel ferrite(NiFe_(2)O_(4))was prepared using a simple wet-chemical synthesis,followed by calcination;bismuth phosphate(BiPO_(4))was also prepared using a hydrothermal method.Further,NiFe_(2)O_(4)/BiPO_(4)nanocomposites were prepared using a hydrothermal technique.Numerous characterization studies,such as structural,morphology,surface area,optical,photoluminescence,and photoelectrochemical investigations,were used to analyze NiFe_(2)O_(4)/BiPO_(4)nanocomposites.The morphology analysis indicated a successful decoration of BiPO_(4)nanorods on the surface of Ni Fe_(2)O_(4)nanoplate.Further,the bandgap of the NiFe_(2)O_(4)/BiPO_(4)nanocomposites was modified owing to the formation of a heterostructure.The as-prepared NiFe_(2)O_(4)/BiPO_(4)nanocomposite exhibited promising properties to be used as a novel heterostructure for tetracycline(TC)and Rhodamine B(Rh B)removal.The NiFe_(2)O_(4)/BiPO_(4)nanocomposite degrades TC(98%)and Rh B(99%)pollutants upon solar-light irradiation within 100 and 60 min,respectively.Moreover,the trapping experiments confirmed the Z-scheme approach of the prepared nanocomposites.The efficient separation and transfer of photogenerated electron-hole pairs rendered by the heterostructure were confirmed by utilizing electrochemical impedance spectroscopy,photocurrent experiments,and photoluminescence.Mott–Schottky measurements were used determine the positions of the conduction and valence bands of the samples,and the detailed mechanism of photocatalytic degradation of toxic pollutants was projected and discussed.展开更多
Lithium-sulfur(Li-S)batteries with high energy density are considered promising energy storage devices for the next generation.Nevertheless,the shuttle effect and the passive layer between the separator and the electr...Lithium-sulfur(Li-S)batteries with high energy density are considered promising energy storage devices for the next generation.Nevertheless,the shuttle effect and the passive layer between the separator and the electrodes still seriously affect the cycle stability and life.Herein,a bimetallic Ni-Co metal-organic framework(MOF)with adsorption and catalytic synergism for polysulfides was successfully synthesized as an electrospinning separator sandwich for Li-S batteries.Introducing porous Ni-Co MOF coatings into the separator provides more adsorption catalytic sites for polysulfides,prevents their diffusion to the anode,and enhances sulfur utilization.Consequently,the improved Li-S batteries with a Ni-Co MOF@PAN(NCMP)electrospun separator delivered excellent rate performance and outstanding cycle stability,yielding an ultra-high initial capacity of 1560 mA h g^(-1)at 0.1 C.Notably,remarkable Li-S battery performance with a discharge capacity of 794 mA h g^(-1)(84.1%capacity retention)was obtained after500 cycles,while delivering a low capacity decay rate of 0.032%during long-term cycling(up to 500cycles)at 1 C.Surprisingly,even at the current density of 2 C,the capacity attenuation rate of 2000 cycles is only 0.034%per cycle.In addition,compared with the Celgard separator,the NCMP separator also had high thermal stability(keeping the separator outline at 200℃)that ensured battery safety and excellent electrolyte wettability(73%porosity and 535%electrolyte absorption)and significantly enhanced the ionic conductivity and Li^(+) transfer number,and protected the surface integrity of the anode.展开更多
The measurement and prediction of gas pulsations are performed along the discharge pipeline of a reciprocating compressor for a refrigerator. A regression based experimental model of the one-dimensional acoustic field...The measurement and prediction of gas pulsations are performed along the discharge pipeline of a reciprocating compressor for a refrigerator. A regression based experimental model of the one-dimensional acoustic field is developed. First, the conventional method for gas pulsation measurement and prediction, which separates the incident and reflected wave of acoustic waves traveling in the frequency domain, is discussed. Then, regression based on our proposed simple model, which is able to predict gas pulsation compared to the conventional method, is introduced for the analysis of a reciprocating compressor(The conventional method requires the value of sound speed in the piping line for the reciprocating compressor). A numerical prediction is made for the regression method. Three power spectrum values along the discharge pipeline are used for analysis, and two values are used for verification. Our results are in a good agreement with the conventional method.展开更多
The development of flexible and wearable devices is mainly required for tactile sensing;as such devices can adapt to complicated nonuniform surfaces,they can be applied to the human body.Nevertheless,it remains necess...The development of flexible and wearable devices is mainly required for tactile sensing;as such devices can adapt to complicated nonuniform surfaces,they can be applied to the human body.Nevertheless,it remains necessary to simultaneously achieve small-scale,portable,and stable developments in such devices.Thus,this work aims at fabricating a novel,lightweight,ultra-flexible,and fiber-shaped coaxial structure with a diameter of 0.51 mm using polydimethylsiloxane/graphene/nylon material,based on piezoresistive and triboelectric principles.The piezoresistive-based robotic-hand-controlled sensor thus realized exhibits a response time of 120 ms and a fast recovery time of 55 ms.Further,the piezoresistive-based sensors effectively feature whisker/joystick-guided behaviors and also sense the human finger contact.Owing to the triboelectric-based selfpowered nanogenerator behavior,the resulting sensor can convert mechanical motion into electrical energy,without adversely affecting human organs.Moreover,this triboelectric-based human finger sensor can be operated under different bending modes at specific angles.Notably,this multifunctional sensor is cost-effective and suitable for various applications,including robotichand-controlled operations in medical surgery,whisker/joystick motions in lightweight drone technology,and navigation with highsensitivity components.展开更多
基金supported by the National Research Foundation of Korea(NRF)funded by the Korean Government,Republic of Korea(Nos.2020R1A2C1012439,2020R1A4A1019227,and 2018R1A2B6002849)。
文摘Global environmental problems have been increasing with the growth of the world economy and have become a crucial issue.To replace fossil fuels,sustainable and eco-friendly catalysts are required for the removal of organic pollutants.In this study,nickel ferrite(NiFe_(2)O_(4))was prepared using a simple wet-chemical synthesis,followed by calcination;bismuth phosphate(BiPO_(4))was also prepared using a hydrothermal method.Further,NiFe_(2)O_(4)/BiPO_(4)nanocomposites were prepared using a hydrothermal technique.Numerous characterization studies,such as structural,morphology,surface area,optical,photoluminescence,and photoelectrochemical investigations,were used to analyze NiFe_(2)O_(4)/BiPO_(4)nanocomposites.The morphology analysis indicated a successful decoration of BiPO_(4)nanorods on the surface of Ni Fe_(2)O_(4)nanoplate.Further,the bandgap of the NiFe_(2)O_(4)/BiPO_(4)nanocomposites was modified owing to the formation of a heterostructure.The as-prepared NiFe_(2)O_(4)/BiPO_(4)nanocomposite exhibited promising properties to be used as a novel heterostructure for tetracycline(TC)and Rhodamine B(Rh B)removal.The NiFe_(2)O_(4)/BiPO_(4)nanocomposite degrades TC(98%)and Rh B(99%)pollutants upon solar-light irradiation within 100 and 60 min,respectively.Moreover,the trapping experiments confirmed the Z-scheme approach of the prepared nanocomposites.The efficient separation and transfer of photogenerated electron-hole pairs rendered by the heterostructure were confirmed by utilizing electrochemical impedance spectroscopy,photocurrent experiments,and photoluminescence.Mott–Schottky measurements were used determine the positions of the conduction and valence bands of the samples,and the detailed mechanism of photocatalytic degradation of toxic pollutants was projected and discussed.
基金supported by the 2022 Yeungnam University Research Grant。
文摘Lithium-sulfur(Li-S)batteries with high energy density are considered promising energy storage devices for the next generation.Nevertheless,the shuttle effect and the passive layer between the separator and the electrodes still seriously affect the cycle stability and life.Herein,a bimetallic Ni-Co metal-organic framework(MOF)with adsorption and catalytic synergism for polysulfides was successfully synthesized as an electrospinning separator sandwich for Li-S batteries.Introducing porous Ni-Co MOF coatings into the separator provides more adsorption catalytic sites for polysulfides,prevents their diffusion to the anode,and enhances sulfur utilization.Consequently,the improved Li-S batteries with a Ni-Co MOF@PAN(NCMP)electrospun separator delivered excellent rate performance and outstanding cycle stability,yielding an ultra-high initial capacity of 1560 mA h g^(-1)at 0.1 C.Notably,remarkable Li-S battery performance with a discharge capacity of 794 mA h g^(-1)(84.1%capacity retention)was obtained after500 cycles,while delivering a low capacity decay rate of 0.032%during long-term cycling(up to 500cycles)at 1 C.Surprisingly,even at the current density of 2 C,the capacity attenuation rate of 2000 cycles is only 0.034%per cycle.In addition,compared with the Celgard separator,the NCMP separator also had high thermal stability(keeping the separator outline at 200℃)that ensured battery safety and excellent electrolyte wettability(73%porosity and 535%electrolyte absorption)and significantly enhanced the ionic conductivity and Li^(+) transfer number,and protected the surface integrity of the anode.
基金Project supported by the 2010 Yeungnam University Research Grant,Korea
文摘The measurement and prediction of gas pulsations are performed along the discharge pipeline of a reciprocating compressor for a refrigerator. A regression based experimental model of the one-dimensional acoustic field is developed. First, the conventional method for gas pulsation measurement and prediction, which separates the incident and reflected wave of acoustic waves traveling in the frequency domain, is discussed. Then, regression based on our proposed simple model, which is able to predict gas pulsation compared to the conventional method, is introduced for the analysis of a reciprocating compressor(The conventional method requires the value of sound speed in the piping line for the reciprocating compressor). A numerical prediction is made for the regression method. Three power spectrum values along the discharge pipeline are used for analysis, and two values are used for verification. Our results are in a good agreement with the conventional method.
基金The study was supported by the National Research Foundation of Korea(NRF)funded by the Ministry of Science(Nos.2022R1I1A1A01064248,2021R1A4A2001658,and 2022R1A2C1003853)the Korea Innovation Foundation(INNOPOLIS)grant funded by the Korea government(MIST)(No.2020-DD-UP-0278)partially supported by the National Research Foundation of Korea grant funded by the Korea Government(MSIP)(No.NRF-2018R1A6A1A03025761).
文摘The development of flexible and wearable devices is mainly required for tactile sensing;as such devices can adapt to complicated nonuniform surfaces,they can be applied to the human body.Nevertheless,it remains necessary to simultaneously achieve small-scale,portable,and stable developments in such devices.Thus,this work aims at fabricating a novel,lightweight,ultra-flexible,and fiber-shaped coaxial structure with a diameter of 0.51 mm using polydimethylsiloxane/graphene/nylon material,based on piezoresistive and triboelectric principles.The piezoresistive-based robotic-hand-controlled sensor thus realized exhibits a response time of 120 ms and a fast recovery time of 55 ms.Further,the piezoresistive-based sensors effectively feature whisker/joystick-guided behaviors and also sense the human finger contact.Owing to the triboelectric-based selfpowered nanogenerator behavior,the resulting sensor can convert mechanical motion into electrical energy,without adversely affecting human organs.Moreover,this triboelectric-based human finger sensor can be operated under different bending modes at specific angles.Notably,this multifunctional sensor is cost-effective and suitable for various applications,including robotichand-controlled operations in medical surgery,whisker/joystick motions in lightweight drone technology,and navigation with highsensitivity components.
