Interfacial water molecules are the most important participants in the hydrogen evolution reaction(HER).Hence,understanding the behavior and role that interfacial water plays will ultimately reveal the HER mechanism.U...Interfacial water molecules are the most important participants in the hydrogen evolution reaction(HER).Hence,understanding the behavior and role that interfacial water plays will ultimately reveal the HER mechanism.Unfortunately,investigating interfacial water is extremely challenging owing to the interference caused by bulk water molecules and complexity of the interfacial environment.Here,the behaviors of interfacial water in different cationic electrolytes on Pd surfaces were investigated by the electrochemistry,in situ core-shell nanostructure enhanced Raman spectroscopy and theoretical simulation techniques.Direct spectral evidence reveals a red shift in the frequency and a decrease in the intensity of interfacial water as the potential is shifted in the positively direction.When comparing the different cation electrolyte systems at a given potential,the frequency of the interfacial water peak increases in the specified order:Li+<Na^(+)<K^(+)<Ca^(2+)<Sr^(2+).The structure of interfacial water was optimized by adjusting the radius,valence,and concentration of cation to form the two-H down structure.This unique interfacial water structure will improve the charge transfer efficiency between the water and electrode further enhancing the HER performance.Therefore,local cation tuning strategies can be used to improve the HER performance by optimizing the interfacial water structure.展开更多
Layered P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_2 is a promising cathode material. It exhibits a high capacity and suitable operating voltage and undergoes a phase transition from P2 to O2 during charge/discharge.Researchers ha...Layered P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_2 is a promising cathode material. It exhibits a high capacity and suitable operating voltage and undergoes a phase transition from P2 to O2 during charge/discharge.Researchers have used Ti substitution to improve the cathode, yet the chemical principles that underpin elemental substitution and functional improvement remain unclear. To clarify these principles, we used in situ Raman spectroscopy to monitor chemical changes in P2–Na2/3 Ni1/3 Mn1/3 Ti1/3 O2 and P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_2 during charge/discharge. Based on the change in the A_(1g) and E_g peaks during charge/discharge, we concluded that Ti substitution compressed the transition metal layer and expanded the planar oxygen layer in the unit cell. Titanium stabilized the P2 phase structure, which improved the cycling stability of P2–NaNMT. Our results provide clear theoretical support for future research on modifying electrodes by elemental substitution.展开更多
Transition-metal oxyhydroxides are attractive catalysts for oxygen evolution reactions(OERs).Further studies for developing transition-metal oxyhydroxide catalysts and understanding their catalytic mechanisms will ben...Transition-metal oxyhydroxides are attractive catalysts for oxygen evolution reactions(OERs).Further studies for developing transition-metal oxyhydroxide catalysts and understanding their catalytic mechanisms will benefit their quick transition to the next catalysts.Herein,Mo-doped CoOOH was designed as a high-performance model electrocatalyst with durability for 20 h at 10 mAcm−2.Additionally,it had an overpotential of 260 mV(glassy carbon)or 215 mV(nickel foam),which was 78 mV lower than that of IrO_(2)(338 mV).In situ,Raman spectroscopy revealed the transformation process of CoOOH.Calculations using the density functional theory showed that during OER,doped Mo increased the spin-up density of states and shrank the spin-down bandgap of the 3d orbits in the reconstructed CoOOH under the electrochemical activation process,which simultaneously optimized the adsorption and electron conduction of oxygen-related intermediates on Co sites and lowered the OER overpotentials.Our research provides new insights into the methodical planning of the creation of transition-metal oxyhydroxide OER catalysts.展开更多
The electrocatalytic oxidation of biomass-derived furfural(FF)feedstocks into 2-furoic acid(FA)holds immense industrial potential in optics,cosmetics,polymers,and food.Herein,we fabricated Co O/Ni O/nickel foam(NF)and...The electrocatalytic oxidation of biomass-derived furfural(FF)feedstocks into 2-furoic acid(FA)holds immense industrial potential in optics,cosmetics,polymers,and food.Herein,we fabricated Co O/Ni O/nickel foam(NF)and Cu_(2)O/Ni O/NF electrodes via in situ pulsed laser irradiation in liquids(PLIL)for the bifunctional electrocatalysis of oxygen evolution reaction(OER)and furfural oxidation reaction(FOR),respectively.Simultaneous oxidation of NF surface to NiO and deposition of CoO and/or Cu_(2)O on NF during PLIL offer distinct advantages for enhancing both the OER and FOR.CoO/NiO/NF electrocatalyst provides a consistently low overpotential of~359 m V(OER)at 10 m A/cm^(2),achieving the maximum FA yield(~16.37 m M)with 61.5%selectivity,79.5%carbon balance,and a remarkable Faradaic efficiency of~90.1%during 2 h of FOR at 1.43 V(vs.reversible hydrogen electrode).Mechanistic pathway via in situ electrochemical-Raman spectroscopy on CoO/NiO/NF reveals the involvement of phase transition intermediates(NiOOH and CoOOH)as surface-active centers during electrochemical oxidation.The carbonyl carbon in FF is attacked by hydroxyl groups to form unstable hydrates that subsequently undergo further oxidation to yield FA products.This method holds promise for large-scale applications,enabling simultaneous production of renewable building materials and fuel.展开更多
Currently, lithium-ion batteries play a key role in energy storage; however, their applications are limited by their low energy density. Here, we design a facile method to prepare mesoporous ZnMn2O4 microspheres with ...Currently, lithium-ion batteries play a key role in energy storage; however, their applications are limited by their low energy density. Here, we design a facile method to prepare mesoporous ZnMn2O4 microspheres with ultrahigh rate performance and ultralong cycling properties by finely tuning the solution viscosity during synthesis. When the current density is raised to 2 A·g^-1, the discharge capacity is maintained at 879 mA·h·g^-1 after 500 cycles. The electro- chemical properties of mesoporous ZnMn2O4 microspheres are better than that for most reported ZnMn2O4. To understand the electrochemical processes on the mesoporous ZnMn2O4 microspheres, in situ Raman spectroscopy is used to investigate the electrode surface. The results show that mesoporous ZnMn2O4 microspheres have a great potential as an alternative to commercial carbon anode materials.展开更多
The composition and evolution of interfacial species play a key role during electrocatalytic process.Unveiling the structural evolution and intermediate during catalytic process by in situ characterization can shed ne...The composition and evolution of interfacial species play a key role during electrocatalytic process.Unveiling the structural evolution and intermediate during catalytic process by in situ characterization can shed new light on the electrocatalytic reaction mechanism and develop highly efficient catalyst.However,directly probing the interfacial species is extremely difficult for most spectroscopic techniques due to complicated interfacial environment and ultra-low surface concentration.Herein,electrochemical core-shell nanoparticle enhanced Raman spectroscopy is utilized to probe the composition and evolution processes of interfacial species on Au@Pt,Au@Co,and Au@PtCo core-shell nanoparticle surfaces.The spectral evidences of interfacial intermediates including hydroxide radical(OH*),superoxide ion(O_(2)^(−)),as well as metal oxide species are directly captured by in situ Raman spectroscopy,which are further confirmed by the both isotopic experiment and density functional theory calculation.These results provide a mechanistic guideline for the rational design of highly efficient electrocatalysts.展开更多
Organic compounds represent an appealing group of electrode materials for rechargeable batteries due to their merits of biomass,sustainability,environmental friendliness,and processability.Disodium terephthalate(Na_(2...Organic compounds represent an appealing group of electrode materials for rechargeable batteries due to their merits of biomass,sustainability,environmental friendliness,and processability.Disodium terephthalate(Na_(2)C_(8)H_(4)O_(4),Na_(2)TP),an organic salt with a theoretical capacity of 255 mAh·g^(-1),is electroactive towards both lithium and sodium.However,its electrochemical energy storage(EES)process has not been directly observed via in situ characterization techniques and the underlying mechanisms are still under debate.Herein,in situ Raman spectroscopy was employed to track the de/lithiation and de/sodiation processes of Na2TP.The appearance and then disappearance of the–COOLi Raman band at 1625 cm^(-1) during the de/lithiation,and the increase and then decrease of the–COONa Raman band at 1615 cm^(-1) during the de/sodiation processes of Na2TP elucidate the one-step with the 2Li+or 2Na+transfer mechanism.We also found that the inferior cycling stability of Na2TP as an anode for sodium-ion batteries(SIBs)than lithium-ion batteries(LIBs)could be due to the larger ion radium of Na+than Li+,which results in larger steric resistance and polarization during EES.The Na2TP,therefore,shows greater changes in spectra during de/sodiation than de/lithiation.We expect that our findings could provide a reference for the rational design of organic compounds for EES.展开更多
The phase transitions among the high-pressure polymorphic forms of CaCO_(3)(cc-Ⅰ,cc-Ⅱ,cc-Ⅲ,and cc-Ⅲb)are investigated by dynamic diamond anvil cell(dDAC)and in situ Raman spectroscopy.Experiments are carried out a...The phase transitions among the high-pressure polymorphic forms of CaCO_(3)(cc-Ⅰ,cc-Ⅱ,cc-Ⅲ,and cc-Ⅲb)are investigated by dynamic diamond anvil cell(dDAC)and in situ Raman spectroscopy.Experiments are carried out at room temperature and high pressures up to 12.8 GPa with the pressurizing rate varying from 0.006 GPa/s to 0.056 GPa/s.In situ observation shows that with the increase of pressure,calcite transforms from cc-Ⅰto cc-Ⅱat~1.5 GPa and from cc-Ⅱto cc-Ⅲat~2.5 GPa,and transitions are independent of the pressurizing rate.Further,as the pressure continues to increase,the cc-Ⅲb begins to appear and coexists with cc-Ⅲwithin a pressure range that is inversely proportional to the pressurizing rate.At the pressurizing rates of 0.006,0.012,0.021,and 0.056 GPa/s,the coexistence pressure ranges of cc-Ⅲand cc-Ⅲb are 2.8 GPa-9.8 GPa,3.1 GPa-6.9 GPa,2.7 GPa-6.0 GPa,and 2.8 GPa-4.5 GPa,respectively.The dependence of the coexistence on the pressurizing rate may result from the influence of pressurizing rate on the activation process of transition by reducing the energy barrier.The higher the pressurizing rate,the lower the energy barrier is,and the easier it is to pull the system out of the coexistence state.The results of this in situ study provide new insights into the understanding of the phase transition of calcite.展开更多
In situ Raman spectroscopic and voltammetric studies indicate that dissociative adsorption of methanol on the rough platinum electrode occurs in the hydrogen ad/desorption potential range, and the dissociative extent ...In situ Raman spectroscopic and voltammetric studies indicate that dissociative adsorption of methanol on the rough platinum electrode occurs in the hydrogen ad/desorption potential range, and the dissociative extent depends on the initial potential of the electrode before contacting methanol, in addition to the contacting time. As the dissociative product, carbon monoxide competes the site of strongly bound hydrogen preferentially, and shifts the ad/desorption potentials of weakly bound hydrogen towards more positive ones gradually with the increase of CO coverage. Whereas, formaldehyde dissociates more easily by far and completely suppresses H-adsorption. The confocal Raman spectroscopy developed on transition metals shows some intriguing advantages in investigating electrocatalytic oxidation of small organic molecules.展开更多
Low electronic conductivity and large volume changes during the(de)lithiation process are the two main challenges for ZnO anode materials used for lithium-ion batteries(LIB).Here,a free-standing,flexible,and binder-fr...Low electronic conductivity and large volume changes during the(de)lithiation process are the two main challenges for ZnO anode materials used for lithium-ion batteries(LIB).Here,a free-standing,flexible,and binder-free LIB electrode composed of ZnO nanorods and carbon cloth(CC)is fabricated.This is then decorated with Ag nanoparticles and finally coated by an amorphous carbon layer to form the hybrid electrode:(C@(Ag&ZnO)).The voids among the nanorods are sufficient to accommodate the volume expansion of the ZnO while the flexible CC,which acts as the current collector,relieves the volume change-induced stress.The Ag nanoparticles are effective in improving the conductivity.This composite electrode shows excellent LIB performance with a stable long cycling life over 500 cycles with a reversible capacity of 1093 mAh g^(-1)at a current density of 200 mA g^(-1).It also shows good rate performance with reversible capacity of 517 mAh g^(-1)under a high-current density of 5000 mA g^(-1).In situ Raman spectroscopy is conducted to investigate the contributions of the amorphous carbon layer to the capacity of the whole electrode and the synergy between the CC and ZnO nanorods.展开更多
Seawater electrolysis,especially in coastlines,is widely considered as a sustainable way of making clean and high-purity H2 from renewable energy;however,the practical viability is challenged severely by the limited a...Seawater electrolysis,especially in coastlines,is widely considered as a sustainable way of making clean and high-purity H2 from renewable energy;however,the practical viability is challenged severely by the limited anode durability resulting from side reactions of chlorine species.Herein,we report an effective Cl−blocking barrier of NiFe-layer double hydroxide(NiFe-LDH)to harmful chlorine chemistry during alkaline seawater oxidation(ASO),a pre-formed surface-derived NiFe-phosphate(Pi)outerlayer.Specifically,the PO_(4)^(3−)-enriched outer-layer is capable of physically and electrostatically inhibiting Cl−adsorption,which protects active Ni^(3+)sites during ASO.The NiFe-LDH with the NiFe-Pi outer-layer(NiFe-LDH@NiFe-Pi)exhibits higher current densities(j)and lower overpotentials to afford 1 A·cm^(−2)(η1000 of 370 mV versusη1000 of 420 mV)than the NiFe-LDH in 1 M KOH+seawater.Notably,the NiFe-LDH@NiFe-Pi also demonstrates longer-term electrochemical durability than NiFe-LDH,attaining 100-h duration at the j of 1 A·cm^(−2).Additionally,the importance of surface-derived PO_(4)^(3−)-enriched outer-layer in protecting the active centers,γ-NiOOH,is explained by ex situ characterizations and in situ electrochemical spectroscopic studies.展开更多
Oxygen evolution reaction(OER)plays a key role in the electrochemical conversion and storage processes,but the sluggish kinetics of OER strongly impedes its large-scale applications.We herein reported the in situ grow...Oxygen evolution reaction(OER)plays a key role in the electrochemical conversion and storage processes,but the sluggish kinetics of OER strongly impedes its large-scale applications.We herein reported the in situ growth of Fe-benzenedicarboxylate(Fe-BDC)on Co(OH)_(2) nanoplates[Fe-BDC/Co(OH)_(2)]that showed remarkably enhanced OER activity than the pristine Co(OH)_(2).The incorporation of Fe species could enhance the intrinsic OER activity of Co and BDC could increase the electrochemically active surface area(ECSA),thus resulting in dramatically enhanced OER activity.In situ Raman spectroscopy characterization disclosed that Fe-CoOOH reconstructed from Fe-BDC/Co(OH)_(2) was the real active site for OER.This work highlights the significance of rational tailoring of the nanostructure and electronic structure of Co(OH)_(2) and provides more opportunities for its widespread applications.展开更多
The reduction and the oxidation of hypophosphite on a Ni-Ag electrode have been studied to provide the information about the phosphorus incorporation mechanisms during the electro-less deposition and the electrodeposi...The reduction and the oxidation of hypophosphite on a Ni-Ag electrode have been studied to provide the information about the phosphorus incorporation mechanisms during the electro-less deposition and the electrodeposition of Ni-P alloys. In the electrooxidation process, an absorbency band around 240 nm, which was ascribed to tbe formation of an intermediate PHO2, was observed by in situ UV-Vis subtractive reflectance spectroscopy. Accordingly, the electrooxidation of hypophosphite might undergo an H abstraction of hypophosphite from the PH bond to form the phosphorus-centred radical PHO2, which was subsequently electrooxidized to the final product, phosphite. In the reduction process Ni-phosphine compound N-(PH3), was observed byin situ surface Raman spectroscopy. The results from the Raman experiments show that, in the NiSO4-free solution, hypophosphite was reduced only to Ni-phosphine compound, while in the case where NiSO4 coexisted in tbe solutions, the Ni-phosphine compound, as an intermediate, was oxidised by Ni2+ to elemental phosphorus in alloys with nickel acting as the catalyst.展开更多
基金the National Key Research and Development Program of China(2019YFA0705400)the National Natural Science Foundation of China(T2293692,21925404,22021001,21991151,and 22002036)+1 种基金the Natural Science Foundation of Fujian Province of China(2021J06001)the National Natural Science Foundation of Henan province(232300421081).
文摘Interfacial water molecules are the most important participants in the hydrogen evolution reaction(HER).Hence,understanding the behavior and role that interfacial water plays will ultimately reveal the HER mechanism.Unfortunately,investigating interfacial water is extremely challenging owing to the interference caused by bulk water molecules and complexity of the interfacial environment.Here,the behaviors of interfacial water in different cationic electrolytes on Pd surfaces were investigated by the electrochemistry,in situ core-shell nanostructure enhanced Raman spectroscopy and theoretical simulation techniques.Direct spectral evidence reveals a red shift in the frequency and a decrease in the intensity of interfacial water as the potential is shifted in the positively direction.When comparing the different cation electrolyte systems at a given potential,the frequency of the interfacial water peak increases in the specified order:Li+<Na^(+)<K^(+)<Ca^(2+)<Sr^(2+).The structure of interfacial water was optimized by adjusting the radius,valence,and concentration of cation to form the two-H down structure.This unique interfacial water structure will improve the charge transfer efficiency between the water and electrode further enhancing the HER performance.Therefore,local cation tuning strategies can be used to improve the HER performance by optimizing the interfacial water structure.
基金supported by the NSFC (21905239, 21925404, and 21775127)the Natural Science Foundation of Shanxi Province of China (201901D211265)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi (2019L0609)。
文摘Layered P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_2 is a promising cathode material. It exhibits a high capacity and suitable operating voltage and undergoes a phase transition from P2 to O2 during charge/discharge.Researchers have used Ti substitution to improve the cathode, yet the chemical principles that underpin elemental substitution and functional improvement remain unclear. To clarify these principles, we used in situ Raman spectroscopy to monitor chemical changes in P2–Na2/3 Ni1/3 Mn1/3 Ti1/3 O2 and P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_2 during charge/discharge. Based on the change in the A_(1g) and E_g peaks during charge/discharge, we concluded that Ti substitution compressed the transition metal layer and expanded the planar oxygen layer in the unit cell. Titanium stabilized the P2 phase structure, which improved the cycling stability of P2–NaNMT. Our results provide clear theoretical support for future research on modifying electrodes by elemental substitution.
基金The National Natural Science Foundation of China(Grant Nos.52072114 and 51922008)the 111 Project(Grant No.D17007),the Henan Center for Outstanding Overseas Scientists(Grant No.GZS2018003)+2 种基金Xinxiang Major Science and Technology Projects(Grant No.21ZD001)Guangdong Innovative and Entrepreneurial Research Team Program(2016ZT06N500)Guangdong Provincial Key Laboratory of Energy Materials for Electric Power(2018B030322001)all provided financial support for this work.
文摘Transition-metal oxyhydroxides are attractive catalysts for oxygen evolution reactions(OERs).Further studies for developing transition-metal oxyhydroxide catalysts and understanding their catalytic mechanisms will benefit their quick transition to the next catalysts.Herein,Mo-doped CoOOH was designed as a high-performance model electrocatalyst with durability for 20 h at 10 mAcm−2.Additionally,it had an overpotential of 260 mV(glassy carbon)or 215 mV(nickel foam),which was 78 mV lower than that of IrO_(2)(338 mV).In situ,Raman spectroscopy revealed the transformation process of CoOOH.Calculations using the density functional theory showed that during OER,doped Mo increased the spin-up density of states and shrank the spin-down bandgap of the 3d orbits in the reconstructed CoOOH under the electrochemical activation process,which simultaneously optimized the adsorption and electron conduction of oxygen-related intermediates on Co sites and lowered the OER overpotentials.Our research provides new insights into the methodical planning of the creation of transition-metal oxyhydroxide OER catalysts.
基金supported by the Korea Basic Science Institute(National research Facilities and Equipment Center)grant funded by the Ministry of Education(2019R1A6C1010042,2021R1A6C103A427)the financial support from the National Research Foundation of Korea(NRF)(2022R1A2C2010686,2022R1A4A3033528,2021R1I1A1A01060380,2021R1C1C2010726,2019H1D3A1A01071209)。
文摘The electrocatalytic oxidation of biomass-derived furfural(FF)feedstocks into 2-furoic acid(FA)holds immense industrial potential in optics,cosmetics,polymers,and food.Herein,we fabricated Co O/Ni O/nickel foam(NF)and Cu_(2)O/Ni O/NF electrodes via in situ pulsed laser irradiation in liquids(PLIL)for the bifunctional electrocatalysis of oxygen evolution reaction(OER)and furfural oxidation reaction(FOR),respectively.Simultaneous oxidation of NF surface to NiO and deposition of CoO and/or Cu_(2)O on NF during PLIL offer distinct advantages for enhancing both the OER and FOR.CoO/NiO/NF electrocatalyst provides a consistently low overpotential of~359 m V(OER)at 10 m A/cm^(2),achieving the maximum FA yield(~16.37 m M)with 61.5%selectivity,79.5%carbon balance,and a remarkable Faradaic efficiency of~90.1%during 2 h of FOR at 1.43 V(vs.reversible hydrogen electrode).Mechanistic pathway via in situ electrochemical-Raman spectroscopy on CoO/NiO/NF reveals the involvement of phase transition intermediates(NiOOH and CoOOH)as surface-active centers during electrochemical oxidation.The carbonyl carbon in FF is attacked by hydroxyl groups to form unstable hydrates that subsequently undergo further oxidation to yield FA products.This method holds promise for large-scale applications,enabling simultaneous production of renewable building materials and fuel.
基金This work was supported by the National Natural Science Foundation of China (Nos. 21522508, 51625402, and 21521004), the Fundamental Research Funds for the Central Universities (No. 20720150039), "111" Project (Nos. B16029 and B17027), and the Thousand Youth Talents Plan of China.
文摘Currently, lithium-ion batteries play a key role in energy storage; however, their applications are limited by their low energy density. Here, we design a facile method to prepare mesoporous ZnMn2O4 microspheres with ultrahigh rate performance and ultralong cycling properties by finely tuning the solution viscosity during synthesis. When the current density is raised to 2 A·g^-1, the discharge capacity is maintained at 879 mA·h·g^-1 after 500 cycles. The electro- chemical properties of mesoporous ZnMn2O4 microspheres are better than that for most reported ZnMn2O4. To understand the electrochemical processes on the mesoporous ZnMn2O4 microspheres, in situ Raman spectroscopy is used to investigate the electrode surface. The results show that mesoporous ZnMn2O4 microspheres have a great potential as an alternative to commercial carbon anode materials.
基金the National Key Research and Development Program of China(No.2020YFB1505800)the National Natural Science Foundation of China(Nos.21925404 and 22021001)+5 种基金the Shenzhen Science and Technology Research Grant(No.JCYJ20200109140416788)the Science and Technology Program of Fujian Province(No.2021Y01010295)the Youth Talent Support Program of Fujian Province(Eyas Plan of Fujian Province 2021)Research Initiation Fund of Jimei University(No.ZQ2021008)the Natural Science Foundation of Fujian Province of China(No.2021J06001)the China Postdoctoral Science Foundation(Nos.2021TQ0188 and 2021M691874).
文摘The composition and evolution of interfacial species play a key role during electrocatalytic process.Unveiling the structural evolution and intermediate during catalytic process by in situ characterization can shed new light on the electrocatalytic reaction mechanism and develop highly efficient catalyst.However,directly probing the interfacial species is extremely difficult for most spectroscopic techniques due to complicated interfacial environment and ultra-low surface concentration.Herein,electrochemical core-shell nanoparticle enhanced Raman spectroscopy is utilized to probe the composition and evolution processes of interfacial species on Au@Pt,Au@Co,and Au@PtCo core-shell nanoparticle surfaces.The spectral evidences of interfacial intermediates including hydroxide radical(OH*),superoxide ion(O_(2)^(−)),as well as metal oxide species are directly captured by in situ Raman spectroscopy,which are further confirmed by the both isotopic experiment and density functional theory calculation.These results provide a mechanistic guideline for the rational design of highly efficient electrocatalysts.
基金supported by the National Natural Science Foundation of China(Nos.22005130,22272069,22004054,and 21925404)the Natural Science Foundation of Fujian Province of China(Nos.2021J01988 and 2020J05163).
文摘Organic compounds represent an appealing group of electrode materials for rechargeable batteries due to their merits of biomass,sustainability,environmental friendliness,and processability.Disodium terephthalate(Na_(2)C_(8)H_(4)O_(4),Na_(2)TP),an organic salt with a theoretical capacity of 255 mAh·g^(-1),is electroactive towards both lithium and sodium.However,its electrochemical energy storage(EES)process has not been directly observed via in situ characterization techniques and the underlying mechanisms are still under debate.Herein,in situ Raman spectroscopy was employed to track the de/lithiation and de/sodiation processes of Na2TP.The appearance and then disappearance of the–COOLi Raman band at 1625 cm^(-1) during the de/lithiation,and the increase and then decrease of the–COONa Raman band at 1615 cm^(-1) during the de/sodiation processes of Na2TP elucidate the one-step with the 2Li+or 2Na+transfer mechanism.We also found that the inferior cycling stability of Na2TP as an anode for sodium-ion batteries(SIBs)than lithium-ion batteries(LIBs)could be due to the larger ion radium of Na+than Li+,which results in larger steric resistance and polarization during EES.The Na2TP,therefore,shows greater changes in spectra during de/sodiation than de/lithiation.We expect that our findings could provide a reference for the rational design of organic compounds for EES.
基金Project supported by the Fund from the Chinese Academy of Sciences (Grant No. QYZDY-SSW-DQC029)the National Natural Science Foundation of China (Grant No. 41674097)
文摘The phase transitions among the high-pressure polymorphic forms of CaCO_(3)(cc-Ⅰ,cc-Ⅱ,cc-Ⅲ,and cc-Ⅲb)are investigated by dynamic diamond anvil cell(dDAC)and in situ Raman spectroscopy.Experiments are carried out at room temperature and high pressures up to 12.8 GPa with the pressurizing rate varying from 0.006 GPa/s to 0.056 GPa/s.In situ observation shows that with the increase of pressure,calcite transforms from cc-Ⅰto cc-Ⅱat~1.5 GPa and from cc-Ⅱto cc-Ⅲat~2.5 GPa,and transitions are independent of the pressurizing rate.Further,as the pressure continues to increase,the cc-Ⅲb begins to appear and coexists with cc-Ⅲwithin a pressure range that is inversely proportional to the pressurizing rate.At the pressurizing rates of 0.006,0.012,0.021,and 0.056 GPa/s,the coexistence pressure ranges of cc-Ⅲand cc-Ⅲb are 2.8 GPa-9.8 GPa,3.1 GPa-6.9 GPa,2.7 GPa-6.0 GPa,and 2.8 GPa-4.5 GPa,respectively.The dependence of the coexistence on the pressurizing rate may result from the influence of pressurizing rate on the activation process of transition by reducing the energy barrier.The higher the pressurizing rate,the lower the energy barrier is,and the easier it is to pull the system out of the coexistence state.The results of this in situ study provide new insights into the understanding of the phase transition of calcite.
基金Financial support by the National Natural Science Foundation of China (29833060 29903009+2 种基金 20073012) and Visiting Scholar Foundation in State Key Labs of Ministry of Education of China is gratefully acknowledged.
文摘In situ Raman spectroscopic and voltammetric studies indicate that dissociative adsorption of methanol on the rough platinum electrode occurs in the hydrogen ad/desorption potential range, and the dissociative extent depends on the initial potential of the electrode before contacting methanol, in addition to the contacting time. As the dissociative product, carbon monoxide competes the site of strongly bound hydrogen preferentially, and shifts the ad/desorption potentials of weakly bound hydrogen towards more positive ones gradually with the increase of CO coverage. Whereas, formaldehyde dissociates more easily by far and completely suppresses H-adsorption. The confocal Raman spectroscopy developed on transition metals shows some intriguing advantages in investigating electrocatalytic oxidation of small organic molecules.
基金support from National Natural Science Foundation of China(Nos:11874144,12174092 and U21A20500)Hubei Provincial Department of Science and Technology(No.2019CFA079)+1 种基金Wuhan Science and Technology Bureau(2020010601012163)Overseas Expertise Introduction Center for Discipline Innovation(D18025).
文摘Low electronic conductivity and large volume changes during the(de)lithiation process are the two main challenges for ZnO anode materials used for lithium-ion batteries(LIB).Here,a free-standing,flexible,and binder-free LIB electrode composed of ZnO nanorods and carbon cloth(CC)is fabricated.This is then decorated with Ag nanoparticles and finally coated by an amorphous carbon layer to form the hybrid electrode:(C@(Ag&ZnO)).The voids among the nanorods are sufficient to accommodate the volume expansion of the ZnO while the flexible CC,which acts as the current collector,relieves the volume change-induced stress.The Ag nanoparticles are effective in improving the conductivity.This composite electrode shows excellent LIB performance with a stable long cycling life over 500 cycles with a reversible capacity of 1093 mAh g^(-1)at a current density of 200 mA g^(-1).It also shows good rate performance with reversible capacity of 517 mAh g^(-1)under a high-current density of 5000 mA g^(-1).In situ Raman spectroscopy is conducted to investigate the contributions of the amorphous carbon layer to the capacity of the whole electrode and the synergy between the CC and ZnO nanorods.
基金supported by the Free Exploration Project of Frontier Technology for Laoshan Laboratory(No.16-02)the National Natural Science Foundation of China(Nos.22072015 and 21927811).
文摘Seawater electrolysis,especially in coastlines,is widely considered as a sustainable way of making clean and high-purity H2 from renewable energy;however,the practical viability is challenged severely by the limited anode durability resulting from side reactions of chlorine species.Herein,we report an effective Cl−blocking barrier of NiFe-layer double hydroxide(NiFe-LDH)to harmful chlorine chemistry during alkaline seawater oxidation(ASO),a pre-formed surface-derived NiFe-phosphate(Pi)outerlayer.Specifically,the PO_(4)^(3−)-enriched outer-layer is capable of physically and electrostatically inhibiting Cl−adsorption,which protects active Ni^(3+)sites during ASO.The NiFe-LDH with the NiFe-Pi outer-layer(NiFe-LDH@NiFe-Pi)exhibits higher current densities(j)and lower overpotentials to afford 1 A·cm^(−2)(η1000 of 370 mV versusη1000 of 420 mV)than the NiFe-LDH in 1 M KOH+seawater.Notably,the NiFe-LDH@NiFe-Pi also demonstrates longer-term electrochemical durability than NiFe-LDH,attaining 100-h duration at the j of 1 A·cm^(−2).Additionally,the importance of surface-derived PO_(4)^(3−)-enriched outer-layer in protecting the active centers,γ-NiOOH,is explained by ex situ characterizations and in situ electrochemical spectroscopic studies.
基金National Key R&D Program of China(No.2020YFB1505703)National Natural Science Foundation of China(Nos.22072101,22075193)+3 种基金Natural Science Foundation of Jiangsu Province,China(Nos.BK20211306,BK20220483)Fund of the Key Technology Initiative of Suzhou Municipal Science and Technology Bureau,China(No.SYG201934)Six Talent Peaks Project in Jiangsu Province,China(No.TD-XCL-006)Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions,China.
文摘Oxygen evolution reaction(OER)plays a key role in the electrochemical conversion and storage processes,but the sluggish kinetics of OER strongly impedes its large-scale applications.We herein reported the in situ growth of Fe-benzenedicarboxylate(Fe-BDC)on Co(OH)_(2) nanoplates[Fe-BDC/Co(OH)_(2)]that showed remarkably enhanced OER activity than the pristine Co(OH)_(2).The incorporation of Fe species could enhance the intrinsic OER activity of Co and BDC could increase the electrochemically active surface area(ECSA),thus resulting in dramatically enhanced OER activity.In situ Raman spectroscopy characterization disclosed that Fe-CoOOH reconstructed from Fe-BDC/Co(OH)_(2) was the real active site for OER.This work highlights the significance of rational tailoring of the nanostructure and electronic structure of Co(OH)_(2) and provides more opportunities for its widespread applications.
基金Project (No. 99C57) supported by the Natural Science Foundation of the Education Commission of Hunan Province
文摘The reduction and the oxidation of hypophosphite on a Ni-Ag electrode have been studied to provide the information about the phosphorus incorporation mechanisms during the electro-less deposition and the electrodeposition of Ni-P alloys. In the electrooxidation process, an absorbency band around 240 nm, which was ascribed to tbe formation of an intermediate PHO2, was observed by in situ UV-Vis subtractive reflectance spectroscopy. Accordingly, the electrooxidation of hypophosphite might undergo an H abstraction of hypophosphite from the PH bond to form the phosphorus-centred radical PHO2, which was subsequently electrooxidized to the final product, phosphite. In the reduction process Ni-phosphine compound N-(PH3), was observed byin situ surface Raman spectroscopy. The results from the Raman experiments show that, in the NiSO4-free solution, hypophosphite was reduced only to Ni-phosphine compound, while in the case where NiSO4 coexisted in tbe solutions, the Ni-phosphine compound, as an intermediate, was oxidised by Ni2+ to elemental phosphorus in alloys with nickel acting as the catalyst.