Amorphous hydroxide on a foamed nickel substrate was fabricated by a simple and efficient electrospinning method for the first time.In untreated alkaline medium,amorphous cobalt(Co)-iron(Fe)hydroxide showed oxygen-evo...Amorphous hydroxide on a foamed nickel substrate was fabricated by a simple and efficient electrospinning method for the first time.In untreated alkaline medium,amorphous cobalt(Co)-iron(Fe)hydroxide showed oxygen-evolution advantages over the typical reference catalyst(RuO_(2)).When tested with a three-electrode system in 1 M KOH,the obtained amorphous PVP/CoFe_(1.3)nanofibers possessed remarkable catalytic activity and stability for the oxygen evolution reaction(OER)with a low overpotential of 0.267 V at 100 mA cm^(-2)and a low Tafel slope of 47.43 mV dec^(-1).The amorphous CoFe microfibers were synthesized by electrospinning,and stable CoFe hydroxides can be further formed in the alkaline environment.The synergistic effect between two different amorphous CoFe-based hydroxides contributed to excellent electrocatalytic activity.Therefore,the design of amorphous CoFe hydroxide enabled the development of a high-efficiency OER catalyst and opens possibilities for the large-scale and environmentally friendly production of water splitting.展开更多
In this study,we reported on the concept and practical use of cation exchange resin(CER)for removing anions in water via pretreating the CER with metal salts.The cation exchange resinsupported iron and magnesium oxide...In this study,we reported on the concept and practical use of cation exchange resin(CER)for removing anions in water via pretreating the CER with metal salts.The cation exchange resinsupported iron and magnesium oxides/hydroxides composite(FeMg/CER)was synthesized and introduced as a new and potential adsorbent for selective removal of nitrate ion in the water environment.Characteristics of FeMg/CER were determined by techniques such as Fouriertransform infrared spectroscopy,scanning electron microscopy,and Xray diffraction.The results showed that FeMg/CER material had a high nitrate adsorption capacity of 200 mg NO_(3)^()·g^(1)with a fast equilibrium adsorption time of 30 min at pH 5.In addition,it had good durability of at least 10 times of regeneration,which could be applied to practical water and wastewater treatment.展开更多
Two-dimensional layered double hydroxides(LDHs)have been identified as promising electrocatalysts for the oxygen evolution reaction(OER);however,the simple and effective synthesis of high-quality LDHs remains extremel...Two-dimensional layered double hydroxides(LDHs)have been identified as promising electrocatalysts for the oxygen evolution reaction(OER);however,the simple and effective synthesis of high-quality LDHs remains extremely challenging and the active sites have not been clarified.Herein,we report a facile solution-reaction method for preparing an ultrathin(thickness<2 nm)nonprecious CoFe-based LDH.Co_(1)Fe_(0.2) LDH delivers a current density of 10 mA cm^(-2) and a high turnover frequency of 0.082 s^(-1) per total 3d metal atoms at a low overpotential of 256 mV.Its mass activity is 277.9 A g^(-1) at an overpotential of 300 mV for the OER.Kinetic studies reveal the Co site as the main active center for the OER.The doped Fe lowers the reaction barrier by accelerating the charge-transfer process.Theoretical calculations reveal that the surface Co sites adjacent to Fe atoms are the active centers for the OER and the subsurface Fe dopants excessively weaken the OH^(*)adsorption,thus increasing the energy barrier of the rate-determining step.This study can guide the rational design of high-performance CoFe-based LDHs for water splitting.展开更多
Sulphur-containing aromatic nitro compounds were rapidly reduced to the corresponding amines in high yields by employing hydrazine hydrate as a hydrogen donor in the presence of iron oxide hydroxide catalyst. It was w...Sulphur-containing aromatic nitro compounds were rapidly reduced to the corresponding amines in high yields by employing hydrazine hydrate as a hydrogen donor in the presence of iron oxide hydroxide catalyst. It was worth noting that the catalyst exhibited extremely high activity. The reduction could be completed within 20-50 min and the yields were up to 97-99 %.展开更多
b-FeOOH nanorods were prepared by a poly ethylene glycol(PEG) assisted precipitation of FeCl_3·6 H_2O aqueous solution with urea. Na_2CO_3 aqueous solution was introduced to maintain their shapes under annealing....b-FeOOH nanorods were prepared by a poly ethylene glycol(PEG) assisted precipitation of FeCl_3·6 H_2O aqueous solution with urea. Na_2CO_3 aqueous solution was introduced to maintain their shapes under annealing. The one-dimensional porous iron oxide nanorods were synthesized successfully. The asprepared catalysts were characterized by X-ray diffraction, transmission electron microscopy, N_2 adsorption-desorption isotherms and X-ray photoelectron spectroscopy. The hydrogenation of nitrobenzene to aniline was taken as probe reaction to evaluate their catalytic performance. FeOOH(iron oxides hydroxide) nanorods, fabricated by annealing b-FeOOH nanorods at 250℃ in Ar atmosphere for 4h, exhibited high catalytic activity for the transfer hydrogenation of nitrobenzene to aniline with hydrazine hydrate as hydrogen donors.展开更多
As a consequence of mining, heavy metal ions can be exposed to the environment hence contaminate ground water and surface water amongst others. The natural polymer chitosan was proved to be an excellent adsorber mater...As a consequence of mining, heavy metal ions can be exposed to the environment hence contaminate ground water and surface water amongst others. The natural polymer chitosan was proved to be an excellent adsorber material for the effective removal of iron and sulfate ions in batch as well as in column experiments. The adsorption behavior of iron ions, as well as sulfate ions was investigated by utilizing chitosan flakes as a natural adsorbent. The removal was studied using adsorbance measurements, SEM and SEM-EDX. The adsorption capacity of chitosan was determined at different times. The received adsorption capacities for iron ions were very promising with a maximum adsorption capacity of 85 mg/g and a rate of separation of 100%. The maximum adsorption capacity obtained for sulfate ions was 188.8 mg/g and a rate of 80%.展开更多
The effective monitoring of trace carcinogens in the environment and daily necessities is very important for humans.Here,Ag-loaded iron hydroxide(Ag/Fe(OH)_(3))was designed as an excellent surface-enhanced Raman scatt...The effective monitoring of trace carcinogens in the environment and daily necessities is very important for humans.Here,Ag-loaded iron hydroxide(Ag/Fe(OH)_(3))was designed as an excellent surface-enhanced Raman scattering(SERS)substrate and used for the trace detection of carcinogenic aromatic amine p-aminoazobenzene(PAAB).Due to the weak binding ability of Fe^(3+)with OH^(−),Fe(OH)_(3)presents a strong coordination ability with Ag than Co(OH)_(2)and Ni(OH)_(2),resulting in the prominent adjustability of Ag/Fe(OH)_(3),including the localized surface plasmon resonance(LSPR)property and energy band structure.On the one hand,the dielectric environment of Ag nanoparticles is changed due to the coordination effect of Ag and OH^(−),among which the LSPR of Ag/Fe(OH)_(3)in the visible region is significantly enhanced.On the other hand,the energy band gap of Ag/Fe(OH)_(3)is reduced by increasing the content of Ag,achieving effective photo-induced charge transfer(PICT)under excitation at 633 nm.Comprehensively,an enhancement factor(EF)of 1.23×10^(6)was achieved for 4-ATP molecules through the synergistic interaction of LSPR and PICT.Importantly,Ag/Fe(OH)_(3)presents an ultra-low detection limit for PAAB(10^(−9)M),which is of great significance for the trace detection of carcinogenic aromatic amines.展开更多
Nitrates leached from agricultural runoff and industrial wastewater seriously pollute surface and underground water.Converting nitrate(NO_(3)-)into ammonia(NH^(4+))by electrochemical methods not only addresses these w...Nitrates leached from agricultural runoff and industrial wastewater seriously pollute surface and underground water.Converting nitrate(NO_(3)-)into ammonia(NH^(4+))by electrochemical methods not only addresses these water pollution issues but also offers a route to produce ammonia.However,an insufficient availability of highly efficient electrocatalysts for selective synthesis of ammonia has hindered the development of this technique.Currently,although many studies exist where single/double metallic nanosheets have been developed to enhance the activity of nitrate reduction to ammonia,rarely has any work focused on exploring the influence of an amorphous single/double metallic hydroxide.Herein,we report on a facile method to prepare a series of nickel-iron hydroxide crossed-nanosheets with an amorphous structure.Electrocatalytic nitrate activity tests showed that the sample with an optimal Ni/Fe ratio(1:1)exhibited high selectivity(90.6%)and faradaic efficiency(74.8%)for ammonia synthesis.15N isotope labelling experiments confirmed the origin of ammonia from nitrate.Both 1H nuclear magnetic resonance(NMR)spectroscopy and UV-Vis spectrophotometry showed almost the same amount of generated ammonia.The online differential electrochemical mass spectrometry(DEMS)results revealed the intermediates during the electroreduction of nitrate to ammonia.XPS results demonstrated the significant role of oxygen vacancies in improving the electrocatalytic performance.Moreover,the structure and activity of materials could be maintained well after long-term testing.展开更多
Non-noble metals are expected to displace the position of the traditional noble metals as catalysts in accelerating sluggish kinetics during water oxidation within hydrogen energy utilization.Among them,nickel-iron-ba...Non-noble metals are expected to displace the position of the traditional noble metals as catalysts in accelerating sluggish kinetics during water oxidation within hydrogen energy utilization.Among them,nickel-iron-based catalysts have been found to be particularly worth developing for their superior catalytic performance in alkaline electrolytes and their high geological abundance.展开更多
Micro-supercapacitors(MSCs)are attractive electrochemical energy storage devices owing to their high power density and extended cycling stability.However,relatively low areal energy density still hinders their practic...Micro-supercapacitors(MSCs)are attractive electrochemical energy storage devices owing to their high power density and extended cycling stability.However,relatively low areal energy density still hinders their practical applications.Here,an asymmetric Mg ion MSC with promising high energy density is fabricated.Firstly,indium tin oxide(ITO)NWs were synthesized by chemical vapor deposition as the excellent current collector.Subsequently,nanostructured Mn_(3)O_(4)and Ppy@FeOOH were deposited on the laser-engraved interdigital structure ITO NWs electrodes as the positive and negative electrodes,respectively.Beneficial from the hierarchical micro-nano structures of active materials,high conductive electron transport pathways,and charge-balanced asymmetric electrodes,the obtained MSC possesses a high potential window of 2.2 V and a high areal capacitance of 107.3 mF cm^(-2)at 0.2 mA cm^(-2).The insitu XRD,VSM,and ex-situ XPS results reveal that the primary energy storage mechanism of Mg ions in negative FeOOH electrode is Mg ions de-/intercalation and phase transition reaction of FeOOH.Furthermore,the MSC exhibits a high specific energy density of 71.18μWh cm^(-2)at a power density of 0.22 mWh cm^(-2)and capacitance retention of 85%after 5000 cycles with unvaried Coulombic efficiency.These results suggest promising applications of our MSC in miniaturized energy storage devices.展开更多
As a kind of metastable aggregation between iron ions and iron hydroxide precipitates,Fe clusters can only be isolated under narrow synthesis conditions.Here,two Fe clusters with different structural models,[Fe_(6)(H_...As a kind of metastable aggregation between iron ions and iron hydroxide precipitates,Fe clusters can only be isolated under narrow synthesis conditions.Here,two Fe clusters with different structural models,[Fe_(6)(H_(2)thmmg)_(6)](Fe_(6))and[Fe_(18)O_(8)(OH)_(8)(H_(2)thmmg)_(10)](Fe_(18)),are constructed based on a rare N-tris(hydroxymethyl)methylglycine(H5thmmg)ligand.The cyclic Fe_(6) can be visualized as a“six-vane windmill”comprised of 6 Fe^(3+)and 6 H_(2)thmmg^(3-)ligands.Unlike the cyclic configuration of Fe_(6),the Fe_(18) cluster features a bricky structure like a“Chinese knot”coordinated by three species,H_(2)thmmg^(3-),OH-and O^(2-).It was obtained by adding more triethylamine to the reactive solution of Fe_(6) which yielded more coordinated species OH-and O^(2-).Moreover,the conversion from Fe_(6) to Fe_(18) was successfully achieved by adding more triethylamine,realizing nuclearity enlargement and structural regulation of Fe clusters.Furthermore,the magnetic properties of Fe_(6) and Fe_(18) exhibit antiferromagnetism.This work reports two novel alkali-regulated Fe clusters and further realizes the transformation of nuclearity and structure,which provides some reference for the structural predesign and adjustment of metal nanoclusters.展开更多
Clean energy technologies such as water splitting and fuel cells have been intensively pursued in the last decade for their free pollution. However, there is plenty of fossil energy consumed in the preparation of the ...Clean energy technologies such as water splitting and fuel cells have been intensively pursued in the last decade for their free pollution. However, there is plenty of fossil energy consumed in the preparation of the catalysts,which results in a heavy pollution. Therefore, it is much desired but challenging to fabricate high-efficiency catalysts without extra energy input. Herein, we used a facile one-pot room-temperature method to synthesize a highly efficient electrocatalyst of nickel iron layered double hydroxide grown on Ni foam(NiFe LDH/NF) for oxygen evolution reaction(OER). The formation of the NiFe LDH follows a dissolutionprecipitation process, in which the acid conditions by hydrolysis of Fe^3+ combined with NO3^- could etch the NF to form Ni^2+. Then, the obtained Ni^2+ was co-precipitated with the hydrolysed Fe^3+ to in situ generate NiFe LDH on the NF. The NiFe LDH/NF exhibits excellent OER performance with a low potential of about 1.411 V vs. reversible hydrogen electrode(RHE) at a current density of 10 m A cm^-2, a small Tafel slope of 42.3 mV dec^-1 and a significantly low potential of ~1.452 V vs. RHE at 100 mA cm^-2 in 1 mol L^-1 KOH. Moreover, the material also keeps its original morphology and structure over 20 h. This energy-efficient strategy to synthesize NiFe LDH is highly promising for widespread application in OER catalyst industry.展开更多
基金National Natural Science Foundation of China(21473013,51203008,21771021,and 21822501)Beijing Nova Program(xx2018115)+1 种基金Fundamental Research Funds for the Central UniversitiesAnalytical and Measurements Fund of Beijing Normal University。
文摘Amorphous hydroxide on a foamed nickel substrate was fabricated by a simple and efficient electrospinning method for the first time.In untreated alkaline medium,amorphous cobalt(Co)-iron(Fe)hydroxide showed oxygen-evolution advantages over the typical reference catalyst(RuO_(2)).When tested with a three-electrode system in 1 M KOH,the obtained amorphous PVP/CoFe_(1.3)nanofibers possessed remarkable catalytic activity and stability for the oxygen evolution reaction(OER)with a low overpotential of 0.267 V at 100 mA cm^(-2)and a low Tafel slope of 47.43 mV dec^(-1).The amorphous CoFe microfibers were synthesized by electrospinning,and stable CoFe hydroxides can be further formed in the alkaline environment.The synergistic effect between two different amorphous CoFe-based hydroxides contributed to excellent electrocatalytic activity.Therefore,the design of amorphous CoFe hydroxide enabled the development of a high-efficiency OER catalyst and opens possibilities for the large-scale and environmentally friendly production of water splitting.
基金Vietnam National University-Ho Chi Minh City under grant number A2020-16-01.
文摘In this study,we reported on the concept and practical use of cation exchange resin(CER)for removing anions in water via pretreating the CER with metal salts.The cation exchange resinsupported iron and magnesium oxides/hydroxides composite(FeMg/CER)was synthesized and introduced as a new and potential adsorbent for selective removal of nitrate ion in the water environment.Characteristics of FeMg/CER were determined by techniques such as Fouriertransform infrared spectroscopy,scanning electron microscopy,and Xray diffraction.The results showed that FeMg/CER material had a high nitrate adsorption capacity of 200 mg NO_(3)^()·g^(1)with a fast equilibrium adsorption time of 30 min at pH 5.In addition,it had good durability of at least 10 times of regeneration,which could be applied to practical water and wastewater treatment.
文摘Two-dimensional layered double hydroxides(LDHs)have been identified as promising electrocatalysts for the oxygen evolution reaction(OER);however,the simple and effective synthesis of high-quality LDHs remains extremely challenging and the active sites have not been clarified.Herein,we report a facile solution-reaction method for preparing an ultrathin(thickness<2 nm)nonprecious CoFe-based LDH.Co_(1)Fe_(0.2) LDH delivers a current density of 10 mA cm^(-2) and a high turnover frequency of 0.082 s^(-1) per total 3d metal atoms at a low overpotential of 256 mV.Its mass activity is 277.9 A g^(-1) at an overpotential of 300 mV for the OER.Kinetic studies reveal the Co site as the main active center for the OER.The doped Fe lowers the reaction barrier by accelerating the charge-transfer process.Theoretical calculations reveal that the surface Co sites adjacent to Fe atoms are the active centers for the OER and the subsurface Fe dopants excessively weaken the OH^(*)adsorption,thus increasing the energy barrier of the rate-determining step.This study can guide the rational design of high-performance CoFe-based LDHs for water splitting.
文摘Sulphur-containing aromatic nitro compounds were rapidly reduced to the corresponding amines in high yields by employing hydrazine hydrate as a hydrogen donor in the presence of iron oxide hydroxide catalyst. It was worth noting that the catalyst exhibited extremely high activity. The reduction could be completed within 20-50 min and the yields were up to 97-99 %.
基金the financial support provided by the National Natural Science Foundation of China (Nos. 91545119,21761132025, 21773269, 21703262, and 51521091)Youth Innovation Promotion Association CAS (No. 2015152)"Strategic Priority Research Program" of the Chinese Academy of Sciences (No. XDA09030103)
文摘b-FeOOH nanorods were prepared by a poly ethylene glycol(PEG) assisted precipitation of FeCl_3·6 H_2O aqueous solution with urea. Na_2CO_3 aqueous solution was introduced to maintain their shapes under annealing. The one-dimensional porous iron oxide nanorods were synthesized successfully. The asprepared catalysts were characterized by X-ray diffraction, transmission electron microscopy, N_2 adsorption-desorption isotherms and X-ray photoelectron spectroscopy. The hydrogenation of nitrobenzene to aniline was taken as probe reaction to evaluate their catalytic performance. FeOOH(iron oxides hydroxide) nanorods, fabricated by annealing b-FeOOH nanorods at 250℃ in Ar atmosphere for 4h, exhibited high catalytic activity for the transfer hydrogenation of nitrobenzene to aniline with hydrazine hydrate as hydrogen donors.
文摘As a consequence of mining, heavy metal ions can be exposed to the environment hence contaminate ground water and surface water amongst others. The natural polymer chitosan was proved to be an excellent adsorber material for the effective removal of iron and sulfate ions in batch as well as in column experiments. The adsorption behavior of iron ions, as well as sulfate ions was investigated by utilizing chitosan flakes as a natural adsorbent. The removal was studied using adsorbance measurements, SEM and SEM-EDX. The adsorption capacity of chitosan was determined at different times. The received adsorption capacities for iron ions were very promising with a maximum adsorption capacity of 85 mg/g and a rate of separation of 100%. The maximum adsorption capacity obtained for sulfate ions was 188.8 mg/g and a rate of 80%.
基金financially supported by the National Natural Science Foundation of China(52022006,12274018,52002380,and 51902012)China Postdoctoral Science Foundation(2022M710300)+2 种基金Ningbo 3315 Innovative Teams Program(Grant No.2019A-14-C)the Member of Youth Innovation Promotion Association Foundation of CAS(Grant No.2023310)Fundamental Research Funds for the Central Universities(FRF-TP-22-001C1).
文摘The effective monitoring of trace carcinogens in the environment and daily necessities is very important for humans.Here,Ag-loaded iron hydroxide(Ag/Fe(OH)_(3))was designed as an excellent surface-enhanced Raman scattering(SERS)substrate and used for the trace detection of carcinogenic aromatic amine p-aminoazobenzene(PAAB).Due to the weak binding ability of Fe^(3+)with OH^(−),Fe(OH)_(3)presents a strong coordination ability with Ag than Co(OH)_(2)and Ni(OH)_(2),resulting in the prominent adjustability of Ag/Fe(OH)_(3),including the localized surface plasmon resonance(LSPR)property and energy band structure.On the one hand,the dielectric environment of Ag nanoparticles is changed due to the coordination effect of Ag and OH^(−),among which the LSPR of Ag/Fe(OH)_(3)in the visible region is significantly enhanced.On the other hand,the energy band gap of Ag/Fe(OH)_(3)is reduced by increasing the content of Ag,achieving effective photo-induced charge transfer(PICT)under excitation at 633 nm.Comprehensively,an enhancement factor(EF)of 1.23×10^(6)was achieved for 4-ATP molecules through the synergistic interaction of LSPR and PICT.Importantly,Ag/Fe(OH)_(3)presents an ultra-low detection limit for PAAB(10^(−9)M),which is of great significance for the trace detection of carcinogenic aromatic amines.
基金supported by the National Natural Science Foundation of China(No.21576211 and 21706191)the Tianjin Science and Technology Program(No.21ZYJDJC00100 and 22ZYJDSS00060)the Program for Tianjin 131 Research Team of Innovative Talents and Tianjin Innovative Research Team in Universities(No.TD13-5031)。
文摘Nitrates leached from agricultural runoff and industrial wastewater seriously pollute surface and underground water.Converting nitrate(NO_(3)-)into ammonia(NH^(4+))by electrochemical methods not only addresses these water pollution issues but also offers a route to produce ammonia.However,an insufficient availability of highly efficient electrocatalysts for selective synthesis of ammonia has hindered the development of this technique.Currently,although many studies exist where single/double metallic nanosheets have been developed to enhance the activity of nitrate reduction to ammonia,rarely has any work focused on exploring the influence of an amorphous single/double metallic hydroxide.Herein,we report on a facile method to prepare a series of nickel-iron hydroxide crossed-nanosheets with an amorphous structure.Electrocatalytic nitrate activity tests showed that the sample with an optimal Ni/Fe ratio(1:1)exhibited high selectivity(90.6%)and faradaic efficiency(74.8%)for ammonia synthesis.15N isotope labelling experiments confirmed the origin of ammonia from nitrate.Both 1H nuclear magnetic resonance(NMR)spectroscopy and UV-Vis spectrophotometry showed almost the same amount of generated ammonia.The online differential electrochemical mass spectrometry(DEMS)results revealed the intermediates during the electroreduction of nitrate to ammonia.XPS results demonstrated the significant role of oxygen vacancies in improving the electrocatalytic performance.Moreover,the structure and activity of materials could be maintained well after long-term testing.
基金supported by Natural Science Foundation of Hubei Province(2021CFB144)the Fundamental Research Funds for the Central Universities(2042021kf0077)as well as Large-scale InstrumentEquipment Sharing Foundation of Wuhan University.
文摘Non-noble metals are expected to displace the position of the traditional noble metals as catalysts in accelerating sluggish kinetics during water oxidation within hydrogen energy utilization.Among them,nickel-iron-based catalysts have been found to be particularly worth developing for their superior catalytic performance in alkaline electrolytes and their high geological abundance.
基金supported by the National Natural Science Foundation of China(No.51972154)the Natural Science Foundation of Gansu Province(No.20JR5RA244)。
文摘Micro-supercapacitors(MSCs)are attractive electrochemical energy storage devices owing to their high power density and extended cycling stability.However,relatively low areal energy density still hinders their practical applications.Here,an asymmetric Mg ion MSC with promising high energy density is fabricated.Firstly,indium tin oxide(ITO)NWs were synthesized by chemical vapor deposition as the excellent current collector.Subsequently,nanostructured Mn_(3)O_(4)and Ppy@FeOOH were deposited on the laser-engraved interdigital structure ITO NWs electrodes as the positive and negative electrodes,respectively.Beneficial from the hierarchical micro-nano structures of active materials,high conductive electron transport pathways,and charge-balanced asymmetric electrodes,the obtained MSC possesses a high potential window of 2.2 V and a high areal capacitance of 107.3 mF cm^(-2)at 0.2 mA cm^(-2).The insitu XRD,VSM,and ex-situ XPS results reveal that the primary energy storage mechanism of Mg ions in negative FeOOH electrode is Mg ions de-/intercalation and phase transition reaction of FeOOH.Furthermore,the MSC exhibits a high specific energy density of 71.18μWh cm^(-2)at a power density of 0.22 mWh cm^(-2)and capacitance retention of 85%after 5000 cycles with unvaried Coulombic efficiency.These results suggest promising applications of our MSC in miniaturized energy storage devices.
基金supported by the National Natural Science Foundation of China(No.22071126).
文摘As a kind of metastable aggregation between iron ions and iron hydroxide precipitates,Fe clusters can only be isolated under narrow synthesis conditions.Here,two Fe clusters with different structural models,[Fe_(6)(H_(2)thmmg)_(6)](Fe_(6))and[Fe_(18)O_(8)(OH)_(8)(H_(2)thmmg)_(10)](Fe_(18)),are constructed based on a rare N-tris(hydroxymethyl)methylglycine(H5thmmg)ligand.The cyclic Fe_(6) can be visualized as a“six-vane windmill”comprised of 6 Fe^(3+)and 6 H_(2)thmmg^(3-)ligands.Unlike the cyclic configuration of Fe_(6),the Fe_(18) cluster features a bricky structure like a“Chinese knot”coordinated by three species,H_(2)thmmg^(3-),OH-and O^(2-).It was obtained by adding more triethylamine to the reactive solution of Fe_(6) which yielded more coordinated species OH-and O^(2-).Moreover,the conversion from Fe_(6) to Fe_(18) was successfully achieved by adding more triethylamine,realizing nuclearity enlargement and structural regulation of Fe clusters.Furthermore,the magnetic properties of Fe_(6) and Fe_(18) exhibit antiferromagnetism.This work reports two novel alkali-regulated Fe clusters and further realizes the transformation of nuclearity and structure,which provides some reference for the structural predesign and adjustment of metal nanoclusters.
基金financially supported by the National Natural Science Foundation of China (21425103 and 21501192)
文摘Clean energy technologies such as water splitting and fuel cells have been intensively pursued in the last decade for their free pollution. However, there is plenty of fossil energy consumed in the preparation of the catalysts,which results in a heavy pollution. Therefore, it is much desired but challenging to fabricate high-efficiency catalysts without extra energy input. Herein, we used a facile one-pot room-temperature method to synthesize a highly efficient electrocatalyst of nickel iron layered double hydroxide grown on Ni foam(NiFe LDH/NF) for oxygen evolution reaction(OER). The formation of the NiFe LDH follows a dissolutionprecipitation process, in which the acid conditions by hydrolysis of Fe^3+ combined with NO3^- could etch the NF to form Ni^2+. Then, the obtained Ni^2+ was co-precipitated with the hydrolysed Fe^3+ to in situ generate NiFe LDH on the NF. The NiFe LDH/NF exhibits excellent OER performance with a low potential of about 1.411 V vs. reversible hydrogen electrode(RHE) at a current density of 10 m A cm^-2, a small Tafel slope of 42.3 mV dec^-1 and a significantly low potential of ~1.452 V vs. RHE at 100 mA cm^-2 in 1 mol L^-1 KOH. Moreover, the material also keeps its original morphology and structure over 20 h. This energy-efficient strategy to synthesize NiFe LDH is highly promising for widespread application in OER catalyst industry.
