As one of prussian blue analogues,Co_(3)[Co(CN)_(6)]_(2) has been explored as a promising anode material for potassium-ion batteries(PIBs) owing to its high potassium storage capacity.Unfortunately,Co_(3)[Co(CN)_(6)]_...As one of prussian blue analogues,Co_(3)[Co(CN)_(6)]_(2) has been explored as a promising anode material for potassium-ion batteries(PIBs) owing to its high potassium storage capacity.Unfortunately,Co_(3)[Co(CN)_(6)]_(2) possesses low electronic conductivity and its structure collapses easily during potassiation and depotassiation,resulting in poor rate performance and cyclic stability.To solve these problems,we develop a facile multi-step method to successfully combine uniformCo_(3)[Co(CN)_(6)]_(2) nanocubes with rGO by C-O-Co bonds.As expected,these chemcial bonds shorten the distance betweenCo_(3)[Co(CN)_(6)]_(2) and rGO to the angstrom meter level,which significantly improve the electronic conductivity ofCo_(3)[Co(CN)_(6)]_(2).Besides,the complete encapsulation ofCo_(3)[Co(CN)_(6)]_(2) nanocubes by rGO endows the structure ofCo_(3)[Co(CN)_(6)]_(2) with high stability,thus withstanding repeated insertion/extraction of potassium-ions without visible morphological and structural changes.Benefiting from the abovementioned structural advantages,the CO3 [Co(CN)6]2/rGO nanocomposite exhibits a high reversible capacity of 400.8 mAh g^(-1) at a current density of 0.1 A g^(-1),an exceptional rate capability of 115.5 mAh g^(-1) at 5 A g^(-1), and an ultralong cycle life of 231.9 mAh g^(-1) at 0.1 A g^(-1) after 1000 cycles.Additionally,the effects of different amounts of rGO and different sizes ofCo_(3)[Co(CN)_(6)]_(2) nanocubes on the potassium storage performance are also studied.This work offers an ideal route to significantly enhance the electrochemical properties of prussian blue analogues.展开更多
An electrochemical quartz crystal impedance system has been applied to monitorgeneration of precipitate and adsorption of the precipitate onto An electrode during electrochmicaloxidation and Fe(CN)_6,3-/Fe(CN),6 4- el...An electrochemical quartz crystal impedance system has been applied to monitorgeneration of precipitate and adsorption of the precipitate onto An electrode during electrochmicaloxidation and Fe(CN)_6,3-/Fe(CN),6 4- electrochemical catalytic oxidation of L-cysteine in phosphateaqueous buffer (pH 7.4). Significant decreases in the resonant frequency and increases in themotional resistance and the static capacitance were found during the precipitate adsorption, and thefrequency shift found in solution was ca. 2 times that in air. Similar responses of quartz crystalimpedance and a white precipitate were obtained during redox titration of L-cysteine solutionusing K_3Fe(CN)_6 solution. FT-IR analysis indicated that the white precipitate is cystine. Theelectrode collection efficiency of the electrogenerated cystine was estimated.展开更多
Electrode material is one of the most important factors affecting the performance of supercapacitors, and electrolyte solution is another. In this work, electrochemical properties of hydroxide zinc carbonate composite...Electrode material is one of the most important factors affecting the performance of supercapacitors, and electrolyte solution is another. In this work, electrochemical properties of hydroxide zinc carbonate composite electrode (HZC) in KOH + K3[Fe(CN)6] electrolyte were studied. It was proved that [Fe(CN)6]3−in electrolyte participated in electrochemical reactions and promoted electron transfer. The specific capacitance of HZC electrode was as high as 920.5 F·g−1 at 1.0 A·g−1 in 1 mol·L−1 KOH and 0.04 mol·L−1 K3[Fe(CN)6] electrolyte, which is 172.9% higher than that in KOH. The combination of HZC electrode and low alkalinity aqueous electrolyte provided the supercapacitor system with good capacitance performance, safety, and environmentally friendly.展开更多
In this work,a field-applicable,simple method for quick detecting chlorogenic acid(CGA)was developed.The method is based on CGA’s antioxidant property.CGA is reported to reduce a mixture solution of FeCl_(3)/K_(3)Fe(...In this work,a field-applicable,simple method for quick detecting chlorogenic acid(CGA)was developed.The method is based on CGA’s antioxidant property.CGA is reported to reduce a mixture solution of FeCl_(3)/K_(3)Fe(CN)_(6)to generate Fe_(4)[Fe(CN)_(6)]_(3),the Prussian blue,in an aqueous solution.This reaction was adopted in this work by using solid-ink printed annuli on a filter-paper as reaction vessels.The reagent is pre-loaded and dried within the solid ink printed circles.In a field test,a drop of a sample solution is directly applied to a reagent-loaded circle.The reaction product within the circle shows a blue color,which is detected by using an iPad(or cellphone)camera as a detector and a light-emitting diode flashlight lamp as a light source.A freely available RGB colorimeter program from Apple store was used to read light intensity of three colors:red,green,blue,and absorbance signal of red and blue light is calculated.The difference of absorbance signal of red light from that of blue light was found having linear relationship with CGA concentration in an aqueous sample solution.This simple method is sensitive with a detection limit of 1.0μg/mL for CGA in sample solution.The technique was used to analyze CGA concentration in green coffee extract,and the analytical results agree well with that obtained using a UV/Vis absorption spectrometric method.The real sample test results demonstrate the usefulness of this simple method for quick detecting CGA in green coffee extract products in field test applications.展开更多
Prussian blue analogues(PBAs)have gained significant popularity as cathode materials for sodium-ion batteries(SIBs)due to their remarkable features such as high capacity and convenient synthesis.However,PBAs usually s...Prussian blue analogues(PBAs)have gained significant popularity as cathode materials for sodium-ion batteries(SIBs)due to their remarkable features such as high capacity and convenient synthesis.However,PBAs usually suffer from kinetic problems during the electrochemical reactions due to sluggish Na~+diffusion in the large crystals,resulting in low-capacity utilization and inferior rate capability.In this study,we present a facile etching method aiming at activating the sodium storage sites and accelerating the Na~+transport of Na_2NiFe(CN)_6(denoted as NaNiHCF)by precisely controlling its morphologies.A progressive corner passivation phenomenon occurred in NaNiHCF during the etching process,which led to a substantial augmentation of the specific surface area as the morphology transitioned from a standard cube to a dice shape.Notably,by controlling the etching time,the obtained NaNiHCF-3 electrode exhibited boosted electrochemical performance with high reversible capacity of 83.5mAh g~(-1)(98.2%of its theoretical capacity),superior rate capability(71.2 mAh g~(-1)at 10 C),and stable cycling life-span at different temperatures.Both experimental and computational methods reveal the remarkably reversible structural evolution process and improved Na~+diffusion coefficient.We believe that this work can serve as an indispensable reference to tailor the structure of PBAs to obtain improved electrochemical performance.展开更多
The development of effective and low-energy-consumption catalysts for CO_(2)conversion into high-value-added products by constructing versatile active sites on the surface of heterogeneous compounds is an ur-gent and ...The development of effective and low-energy-consumption catalysts for CO_(2)conversion into high-value-added products by constructing versatile active sites on the surface of heterogeneous compounds is an ur-gent and challenging task.In this study,a stable and well-defined heterogeneous cobalt hexacyanocobal-tate(Co_(3)[Co(CN)_(6)]_(2)),typical cobalt Prussian blue analogue(CoCo-PBA)modified with tetrabutylammo-nium bromide(TBAB),is proven to be the superior catalyst for CO_(2)and epoxide coupling to produce cyclic carbonates with>99%yield under mild reaction conditions(1.0 MPa,65℃).Based on a series of characterizations,it is revealed that the CoCo-PBA structure can maintain relatively high thermal and chemical stability.Recycling experiments exhibited that the CoCo-PBA system could retain 98%of the original activity after six reaction rounds.The CoCo-PBA/TBAB catalytic system was also highly active for coupling CO_(2)with other industrial-grade epoxides.These results show the Co Co-PBA catalytic system potential flexibility and the generality of the catalyst preparation strategy.展开更多
基金supported by the National Natural Science Foundation of China(51577094)the Natural Science Foundation of Jiangsu Province of China(BK20180086)。
文摘As one of prussian blue analogues,Co_(3)[Co(CN)_(6)]_(2) has been explored as a promising anode material for potassium-ion batteries(PIBs) owing to its high potassium storage capacity.Unfortunately,Co_(3)[Co(CN)_(6)]_(2) possesses low electronic conductivity and its structure collapses easily during potassiation and depotassiation,resulting in poor rate performance and cyclic stability.To solve these problems,we develop a facile multi-step method to successfully combine uniformCo_(3)[Co(CN)_(6)]_(2) nanocubes with rGO by C-O-Co bonds.As expected,these chemcial bonds shorten the distance betweenCo_(3)[Co(CN)_(6)]_(2) and rGO to the angstrom meter level,which significantly improve the electronic conductivity ofCo_(3)[Co(CN)_(6)]_(2).Besides,the complete encapsulation ofCo_(3)[Co(CN)_(6)]_(2) nanocubes by rGO endows the structure ofCo_(3)[Co(CN)_(6)]_(2) with high stability,thus withstanding repeated insertion/extraction of potassium-ions without visible morphological and structural changes.Benefiting from the abovementioned structural advantages,the CO3 [Co(CN)6]2/rGO nanocomposite exhibits a high reversible capacity of 400.8 mAh g^(-1) at a current density of 0.1 A g^(-1),an exceptional rate capability of 115.5 mAh g^(-1) at 5 A g^(-1), and an ultralong cycle life of 231.9 mAh g^(-1) at 0.1 A g^(-1) after 1000 cycles.Additionally,the effects of different amounts of rGO and different sizes ofCo_(3)[Co(CN)_(6)]_(2) nanocubes on the potassium storage performance are also studied.This work offers an ideal route to significantly enhance the electrochemical properties of prussian blue analogues.
文摘An electrochemical quartz crystal impedance system has been applied to monitorgeneration of precipitate and adsorption of the precipitate onto An electrode during electrochmicaloxidation and Fe(CN)_6,3-/Fe(CN),6 4- electrochemical catalytic oxidation of L-cysteine in phosphateaqueous buffer (pH 7.4). Significant decreases in the resonant frequency and increases in themotional resistance and the static capacitance were found during the precipitate adsorption, and thefrequency shift found in solution was ca. 2 times that in air. Similar responses of quartz crystalimpedance and a white precipitate were obtained during redox titration of L-cysteine solutionusing K_3Fe(CN)_6 solution. FT-IR analysis indicated that the white precipitate is cystine. Theelectrode collection efficiency of the electrogenerated cystine was estimated.
文摘Electrode material is one of the most important factors affecting the performance of supercapacitors, and electrolyte solution is another. In this work, electrochemical properties of hydroxide zinc carbonate composite electrode (HZC) in KOH + K3[Fe(CN)6] electrolyte were studied. It was proved that [Fe(CN)6]3−in electrolyte participated in electrochemical reactions and promoted electron transfer. The specific capacitance of HZC electrode was as high as 920.5 F·g−1 at 1.0 A·g−1 in 1 mol·L−1 KOH and 0.04 mol·L−1 K3[Fe(CN)6] electrolyte, which is 172.9% higher than that in KOH. The combination of HZC electrode and low alkalinity aqueous electrolyte provided the supercapacitor system with good capacitance performance, safety, and environmentally friendly.
基金Killgore Research Grant Program of West Texas A&M University for providing fund to purchase the solid ink printer used in this work
文摘In this work,a field-applicable,simple method for quick detecting chlorogenic acid(CGA)was developed.The method is based on CGA’s antioxidant property.CGA is reported to reduce a mixture solution of FeCl_(3)/K_(3)Fe(CN)_(6)to generate Fe_(4)[Fe(CN)_(6)]_(3),the Prussian blue,in an aqueous solution.This reaction was adopted in this work by using solid-ink printed annuli on a filter-paper as reaction vessels.The reagent is pre-loaded and dried within the solid ink printed circles.In a field test,a drop of a sample solution is directly applied to a reagent-loaded circle.The reaction product within the circle shows a blue color,which is detected by using an iPad(or cellphone)camera as a detector and a light-emitting diode flashlight lamp as a light source.A freely available RGB colorimeter program from Apple store was used to read light intensity of three colors:red,green,blue,and absorbance signal of red and blue light is calculated.The difference of absorbance signal of red light from that of blue light was found having linear relationship with CGA concentration in an aqueous sample solution.This simple method is sensitive with a detection limit of 1.0μg/mL for CGA in sample solution.The technique was used to analyze CGA concentration in green coffee extract,and the analytical results agree well with that obtained using a UV/Vis absorption spectrometric method.The real sample test results demonstrate the usefulness of this simple method for quick detecting CGA in green coffee extract products in field test applications.
基金financially supported from the National Natural Science Foundation of China(U20A20249,21972108,and 22209125)。
文摘Prussian blue analogues(PBAs)have gained significant popularity as cathode materials for sodium-ion batteries(SIBs)due to their remarkable features such as high capacity and convenient synthesis.However,PBAs usually suffer from kinetic problems during the electrochemical reactions due to sluggish Na~+diffusion in the large crystals,resulting in low-capacity utilization and inferior rate capability.In this study,we present a facile etching method aiming at activating the sodium storage sites and accelerating the Na~+transport of Na_2NiFe(CN)_6(denoted as NaNiHCF)by precisely controlling its morphologies.A progressive corner passivation phenomenon occurred in NaNiHCF during the etching process,which led to a substantial augmentation of the specific surface area as the morphology transitioned from a standard cube to a dice shape.Notably,by controlling the etching time,the obtained NaNiHCF-3 electrode exhibited boosted electrochemical performance with high reversible capacity of 83.5mAh g~(-1)(98.2%of its theoretical capacity),superior rate capability(71.2 mAh g~(-1)at 10 C),and stable cycling life-span at different temperatures.Both experimental and computational methods reveal the remarkably reversible structural evolution process and improved Na~+diffusion coefficient.We believe that this work can serve as an indispensable reference to tailor the structure of PBAs to obtain improved electrochemical performance.
基金financial support of the National Natural Science Foundation of China (Nos.21774108 and 51973190)。
文摘The development of effective and low-energy-consumption catalysts for CO_(2)conversion into high-value-added products by constructing versatile active sites on the surface of heterogeneous compounds is an ur-gent and challenging task.In this study,a stable and well-defined heterogeneous cobalt hexacyanocobal-tate(Co_(3)[Co(CN)_(6)]_(2)),typical cobalt Prussian blue analogue(CoCo-PBA)modified with tetrabutylammo-nium bromide(TBAB),is proven to be the superior catalyst for CO_(2)and epoxide coupling to produce cyclic carbonates with>99%yield under mild reaction conditions(1.0 MPa,65℃).Based on a series of characterizations,it is revealed that the CoCo-PBA structure can maintain relatively high thermal and chemical stability.Recycling experiments exhibited that the CoCo-PBA system could retain 98%of the original activity after six reaction rounds.The CoCo-PBA/TBAB catalytic system was also highly active for coupling CO_(2)with other industrial-grade epoxides.These results show the Co Co-PBA catalytic system potential flexibility and the generality of the catalyst preparation strategy.
