The persistent stability of ruthenium dioxide(RuO_(2))in acidic oxygen evolution reactions(OER)is compromised by the involvement of lattice oxygen(LO)and metal dissolution during the OER process.Heteroatom doping has ...The persistent stability of ruthenium dioxide(RuO_(2))in acidic oxygen evolution reactions(OER)is compromised by the involvement of lattice oxygen(LO)and metal dissolution during the OER process.Heteroatom doping has been recognized as a viable strategy to foster the stability of RuO_(2)for acidic OER applications.This study presented an ion that does not readily gain or lose electrons,Ba^(2+),into RuO_(2)(Ba-RuO_(2))nanosheet(NS)catalyst that increased the number of exposed active sites,achieving a current density of 10 mA/cm^(2)with an overpotential of only 229 mV and sustaining this output for over 250 h.According to density functional theory(DFT)and X-ray absorption spectroscopy,Ba doping resulted in a longer Ru-O bond length,which in turn diminished the covalency of the bond.This alteration curtailed the involvement of LO and the dissolution of ruthenium(Ru),thereby markedly improving the durability of the catalyst over extended periods.Additionally,attenuated total reflectance-surface enhanced infrared absorption spectroscopy analysis substantiated that the OER mechanism shifted from a LO-mediated pathway to an adsorbate evolution pathway due to Ba doping,thereby circumventing Ru over-oxidation and further enhancing the stability of RuO_(2).Furthermore,DFT findings uncovered that Ba doping optimizes the adsorption energy of intermediates,thus enhancing the OER activity in acidic environments.This study offers a potent strategy to guide future developments on Ru-based oxide catalysts'stability in an acidic environment.展开更多
Ruthenium dioxide(RuO_(2))is one of the most promising acidic oxygen evolution reaction(OER)catalysts to replace the expensive and prevalent iridium(Ir)-based materials.However,the lattice oxygen oxidation induced Ru ...Ruthenium dioxide(RuO_(2))is one of the most promising acidic oxygen evolution reaction(OER)catalysts to replace the expensive and prevalent iridium(Ir)-based materials.However,the lattice oxygen oxidation induced Ru dissolution during OER compromises the activity and stability.Amorphous materials have been identified as a viable strategy to promote the stability of RuO_(2)in acidic OER applications.This study reported a nanoporous amorphous-rich RuMnO_(x)(A-RuMnO_(x))aerogel for efficient and stable acidic OER.Compared with highly crystalline RuMnO_(x),the weakened Ru–O covalency of A-RuMnO_(x)by forming amorphous structure is favorable to inhibiting the oxidation of lattice oxygen.Meanwhile,this also optimizes the electronic structure of Ru sites from overoxidation and reduces the reaction energy barrier of the rate-determining step.As a result,A-RuMnO_(x)aerogel exhibits an ultra-low overpotential of 145 mV at 10 mA cm^(-2)and durability exceeding 100 h,as well as high mass activity up to 153 mA mg^(-1)_(Ru)at 1.5 V vs.reversible hydrogen electrode(RHE).This work provides valuable guidance for preparing highly active and stable Ru-based catalysts for acidic OER.展开更多
The copper-based electrocatalysts feature attractive potentials of converting CO_(2)into multi-carbon(C_(2+))products,while the instability of Cu-O often induces the reduction of Cu^(+)/Cu^(0) catalytic sites at the c...The copper-based electrocatalysts feature attractive potentials of converting CO_(2)into multi-carbon(C_(2+))products,while the instability of Cu-O often induces the reduction of Cu^(+)/Cu^(0) catalytic sites at the cathode and refrains the capability of stable electrolysis especially at high powers.In this work,we developed an Erbium(Er)oxide-modified Cu(Er-O-Cu)catalyst with enhanced covalency of Cu-O and more stable active sites.The f-p-d coupling strengthens the covalency of Cu-O,and the stability of Cu^(+)sites under electroreduction condition is critical for promoting the C-C coupling and improving the C_(2+)product selectivity.As a result,the Er-O-Cu sites exhibited a high Faradaic efficiency of C_(2+)products(FEC_(2+))of 86%at 2200 mA cm^(-2),and a peak partial current density of|j_(C2+)|of 1900 mA cm^(-2),comparable to the best reported values for the CO_(2)-to-C_(2+)electroreduction.The CO_(2)electrolysis by the Er-O-Cu sites was further scaled up to 100 cm^(2)to achieve high-power(~200 W)electrolysis with ethylene production rate of 16 mL min^(-1).展开更多
Transition metal oxides have garnered significant attention as electrocatalysts for the oxygen reduction reaction(ORR)and the oxygen evolution reaction(OER).However,their sluggish reaction kinetics and poor stability ...Transition metal oxides have garnered significant attention as electrocatalysts for the oxygen reduction reaction(ORR)and the oxygen evolution reaction(OER).However,their sluggish reaction kinetics and poor stability hinder commercial applications.Herein,we report the synthesis of a bimetallic cobalt manganese oxide,Co_(0.99)Mn_(2.01)O_(4)(CMO),synthesized via a hydrothermal technique,which serves as a highly efficient bifunctional ORR/OER electrocatalyst owing to its impressive halfwave potential of 0.767 V and low overpotential of 1.677 V at 10 mA cm^(-2).Theoretical calculations revealed that the d-band centers of Co 3d and Mn 3d in CMO,located at tetrahedral and octahedral sites,are positioned near the Fermi level,facilitating the adsorption of electrocatalytic intermediates.Furthermore,the distance between the Co 3d and O 2p band centers in CMO is smaller than that in Co_(3)O_(4),and the distance between the Mn 3d and O 2p band centers in CMO is shorter than that in Mn_(2)O_(3),indicating that the Co–O and Mn–O bonds in CMO exhibit greater covalency,significantly enhancing ORR/OER activity.Notably,CMO serves as an advanced air electrode material for rechargeable zinc-air batteries(ZABs),demonstrating improved charge–discharge performance with a low voltage gap of 0.87 V at 5 mA cm^(-2),high peak power density of 124 mW cm^(-2),and excellent cycle stability of over 540 h at 5 mA cm^(-2).This superior ORR/OER activity,combined with the simple material combination,makes CMO a promising catalyst for rechargeable ZABs.展开更多
The optical absorption spectra of the covalent crystals ZnX(X=S,Se) doped with Co 2+ are studied using the double covalency factors,which considers the anisotropic distortion of e g and t 2g orbits for d el...The optical absorption spectra of the covalent crystals ZnX(X=S,Se) doped with Co 2+ are studied using the double covalency factors,which considers the anisotropic distortion of e g and t 2g orbits for d electron.When the paramagnetic g factor is calculated,the contributions of the spin orbit coupling from the ligand ions are taken into account besides that from the central ion,which is the double ξ model.The calculated results indicate that the theoretical values coincide with the experimental values very well.This suggests that the method presented in this paper could be more valid to some strongly covalent crystals.展开更多
High‐entropy materials are emerging electrocatalysts by integrating five or more elements into one single crystallographic phase to optimize the electronic structures and geometric environments.Here,a rocksalt‐type ...High‐entropy materials are emerging electrocatalysts by integrating five or more elements into one single crystallographic phase to optimize the electronic structures and geometric environments.Here,a rocksalt‐type high‐entropy oxide Mg_(0.2)Co_(0.2)Ni_(0.2)Cu_(0.2)Zn_(0.2)O(HEO)is developed as an electrocatalyst towards the oxygen evolution reaction(OER).The obtained HEO features abundant cation and oxygen vacancies originating from the lattice mismatch of neighboring metal ions,together with enlarged Co/Ni‒O covalency due to the introduction of less electronegative Mg and Zn.As a result,the HEO exhibits superior intrinsic OER activities,delivering a turnover frequency(TOF)15 and 84 folds that of CoO and NiO at 1.65 V,respectively.This study provides a mechanistic understanding of the enhanced OER on HEO and demonstrates the potential of high‐entropy strategy in developing efficient oxygen electrocatalysts by elaborately incorporating low‐cost elements with lower electronegativity.展开更多
The relationship between bond valence and bond covalency in RMn2O5 (R = La, Pr, Nd.Sm, Eu) has been investigated by a semiempirical method. This method is the generalization of thedielectric description theory of Phil...The relationship between bond valence and bond covalency in RMn2O5 (R = La, Pr, Nd.Sm, Eu) has been investigated by a semiempirical method. This method is the generalization of thedielectric description theory of Phillips. Van Vechten, Levine and Tanaka scheme. The resultsindicate that larger valences usually result in higher bond covalencies, in good agreement with thepoint that the excess charge in the bonding region is the origin of formation of bond covalency.Other factors, such as oxidation state of elements, only make a small contribution to bondcovalency.展开更多
Exploring efficient,cost-effective,and durable electrocatalysts for electrochemical oxygen evolution reaction(OER)is pivotal for the large-scale application of water electrolysis.Recent advance has demonstrated that t...Exploring efficient,cost-effective,and durable electrocatalysts for electrochemical oxygen evolution reaction(OER)is pivotal for the large-scale application of water electrolysis.Recent advance has demonstrated that the activity of electrocatalysts exhibits a strong dependence on the surface electronic structure.Herein,a series of ultrathin metal silicate hydroxide nanosheets(UMSHNs)M_(3)Si_(2)O_(5)(OH)_(4)(M=Fe,Co,and Ni)synthesized without surfactant are introduced as highly active OER electrocatalysts.Cobalt silicate hydroxide nanosheets show an optimal OER activity with overpotentials of 287 and 358 m V at 1 and 10 m A cm^(-2),respectively.Combining experimental and theoretical studies,it is found that the OER activity of UMSHNs is dominated by the metal-oxygen covalency(MOC).High OER activity can be achieved by having a moderate MOC as reflected by aσ^(*)-orbital(e_(g))filling near unity and moderate[3d]/[2p]ratio.Moreover,the UMSHNs exhibit favorable chemical stability under oxidation potential.This contribution provides a scientific guidance for further development of active metal silicate hydroxide catalysts.展开更多
The increasing demand for green hydrogen production requires the development of advanced ruthenium(Ru)-based oxide catalysts for the anodic oxygen evolution reaction(OER).Here,we report the development of a Ga-doped R...The increasing demand for green hydrogen production requires the development of advanced ruthenium(Ru)-based oxide catalysts for the anodic oxygen evolution reaction(OER).Here,we report the development of a Ga-doped RuO_(2)catalyst(GaRuO_(2))that demonstrates enhanced OER performance attributed to modulated Ru-O bond covalency.The fully occupied 3d orbital of Ga stabilizes its oxidation state during OER,while its atomic radius,similar to Ru,helps maintain the initial crystal lattice structure upon doping.In-situ characterization,kinetic analysis and theoretical calculations reveal that the weakened Ru-O bond covalency lowers the energy barriers for *OH and *OOH formation,thus contributing to an enhanced OER performance.The resultant Ga-RuO_(2)achieves a current density of 10 mA cm^(-2) at a low overpotential of 203 mV and demonstrates durable operation for 500 h in acid.This work provides valuable insights into the electronic structure engineering of Ru-based catalysts for practical water electrolysis applications.展开更多
Oxygen evolution reaction(OER)is crucial for hydrogen production as well as other energy storage technologies.CoFe-layered double hydroxide(CoFe-OH)has been widely considered as one of the most efficient electrocataly...Oxygen evolution reaction(OER)is crucial for hydrogen production as well as other energy storage technologies.CoFe-layered double hydroxide(CoFe-OH)has been widely considered as one of the most efficient electrocatalysts for OER in basic aqueous solution.However,it still suffers from low activity in neutral electrolyte.This paper describes partially oxidized CoFe-OH(PO-CoFe-OH)with enhanced covalency of M-O bonds and displays enhanced OER performance under mild condition.Mechanism studies reveal the suitably enhanced M-O covalency in PO-CoFe-OH shifts the OER mechanism to lattice oxygen oxidation mechanism and also promotes the rate-limiting deprotonation,providing superior OER performance.It just requires the overpotentials of 186 and 365 mV to drive the current density densities of 1 and 10 mA·cm^(-2) in 0.1 M KHCO_(3) aqueous solution(pH=8.3),respectively.It provides a new process for rational design of efficient catalysts for water oxidation in mild conditions.展开更多
Oxidative desulfurization(ODS)is a promising technology to produce clean fuel with requiring superior catalysts to lower kinetic barriers.Although most ODS catalysts are based on crystalline transition-metal oxides(TM...Oxidative desulfurization(ODS)is a promising technology to produce clean fuel with requiring superior catalysts to lower kinetic barriers.Although most ODS catalysts are based on crystalline transition-metal oxides(TMOs),extraordinary activity also can be achieved with amorphous TMOs.However,the origin of the remarkable catalytic activity of the amorphous TMOs remains greatly ambiguous.Here,we found the crucial role of Mo–O covalency in ruling the intrinsic catalytic activity of amorphous molybdenum oxides(MoO_(x)).Experimental and theoretical analysis indicated that the nonequivalent connectivity in the amorphous structure strongly enhanced Mo–O covalency,thereby increasing the content of electrophilic oxygen and nucleophilic molybdenum to favor the MoO_(x)–H_(2)O_(2) interaction.With the boosted Mo–O covalency to improve the flexibility of the charge state,the amorphous MoO_(x)-based composite catalyst(PE-MoO_(x)/S-0.05)exhibited outstanding catalytic activity for ODS of fuel oil.The turnover frequency(TOF)value of the catalyst(18.63 h^(-1))was almost an order of magnitude higher than that of most reported crystalline MoO_(x)/molecular sieve composite catalysts.The in-depth understanding of the origin of the amorphous TMOs activity for ODS provides a valuable reference for developing ODS catalysts.展开更多
It was found that the highly covalent nature of the metal-ligand interactions in the Fe-S cluster clearly played an important role in determining the reactivity of the sites. A semi-empirical model, based on the Phill...It was found that the highly covalent nature of the metal-ligand interactions in the Fe-S cluster clearly played an important role in determining the reactivity of the sites. A semi-empirical model, based on the Phillips theory of bonding was developed for quantitative explanation of covalency in Fe-S cluster, showing that Mossbauer spectroscopy and electronic absorption spectroscopy provided the direct experimental probe of covalency of Fe-S4 clusters.展开更多
Enhancing the activity of fragile enzymes is greatly useful for various purposes,including fabrication of enzyme-based immunosensors.Herein,we report a defect-engineering strategy for encapsulating enzymes within cova...Enhancing the activity of fragile enzymes is greatly useful for various purposes,including fabrication of enzyme-based immunosensors.Herein,we report a defect-engineering strategy for encapsulating enzymes within covalent organic frameworks(COFs),enabling the resulting immobilized enzymes with excellent catalytic activity and stability to construct high performance immunosensors.In this design,by consciously introducing monoaldehyde ligands into the imine-linked COFs structure,we have precisely customized the structural defects to improve enzyme loading capacity and conformational stability.Defect-engineering interaction modulation between enzymes and COFs drives the enhancement of catalytic performance.Compared to the pristine COFs,the enzyme@defective COFs composites with optimally tuned catalytic performance exhibit a 4.49-fold enhancement in enzymatic activity.Furthermore,it is demonstrated that the stable skeletons of COFs provide exceptional protection for the enzymes against external perturbations.Thereafter,the optimized enzyme@defective COFs are employed to fabricate immunosensor.We have successfully established a detection method for prostate-specific antigen(PSA),achieving a low detection limit of 0.09 ng/mL.More importantly,the developed immunosensor has successfully distinguished the prostate cancer patients from healthy individuals.This work establishes a novel paradigm for enzyme immobilization,ultimately empowering the construction of a PSA immunosensor with high sensitivity,remarkable operational stability,and great clinical application potential.展开更多
Constructing catalysts featuring an ordered structure,stable performance,and uniformly dispersed catalytic sites is vital for the epoxidation of small-molecular olefins.Here,we design catalysts by tracing the oxidatio...Constructing catalysts featuring an ordered structure,stable performance,and uniformly dispersed catalytic sites is vital for the epoxidation of small-molecular olefins.Here,we design catalysts by tracing the oxidationprocess origin and synthesize a series of highly dispersed metal porphyrin-based covalent organic frameworks(COFs)materials.The aim is to efficiently oxidize the C-H bonds of cumene by air to in-situ generate organic peroxides at a safe concentration,and integrate the multi-step oxidation method of cumene in industry into a one-step method for olefins’epoxidation.The carbonyl-ruthenium COF(Ru-COF-1)exhibits excellent performance,with 98% epoxide selectivity,1221.77 h^(-1) productivity,and over 95% selectivity after 9 cycles for 1-hexene.Analysis of structure-properties-catalytic relationships of Ru-COF-1 shows that,compared with Ru-porphyrins and metal-free COFs,the enhanced reaction performance mainly results from Ru metal introduction,which promotes benzylic proton transfer in cumene.Besides,Ru-COF-1’s porous,ordered structure aids oxygen enrichment,forming active peroxy radicals with the cumene carboncentered radicals formed on the catalyst surface.Ru-H sites then accelerate active oxygen transfer from peroxy radicals,enabling olefin tandem epoxidation.Density functional theory(DFT)calculations verify the reaction mechanism,and this work offers a reference for the design of catalysts for the green,safe,and efficient oxidation of olefins.展开更多
Conductive elastomers combining micromechanical sensitivity,lightweight adaptability,and environmental sustainability are critically needed for advanced flexible electronics requiring precise responsiveness and long-t...Conductive elastomers combining micromechanical sensitivity,lightweight adaptability,and environmental sustainability are critically needed for advanced flexible electronics requiring precise responsiveness and long-term wearability;however,the integration of these properties remains a significant challenge.Here,we present a biomass-derived conductive elastomer featuring a rationally engineered dynamic crosslinked network integrated with a tunable microporous architecture.This structural design imparts pronounced micromechanical sensitivity,an ultralow density(~0.25 g cm^(−3)),and superior mechanical compliance for adaptive deformation.Moreover,the unique micro-spring effect derived from the porous architecture ensures exceptional stretchability(>500%elongation at break)and superior resilience,delivering immediate and stable electrical response under both subtle(<1%)and large(>200%)mechanical stimuli.Intrinsic dynamic interactions endow the elastomer with efficient room temperature self-healing and complete recyclability without compromising performance.First-principles simulations clarify the mechanisms behind micropore formation and the resulting functionality.Beyond its facile and mild fabrication process,this work establishes a scalable route toward high-performance,sustainable conductive elastomers tailored for next-generation soft electronics.展开更多
To meet the growing needs of flexible and wearable electronics,stretchable energy storage devices—especially supercapacitors(SCs)—have become a key focus in advanced energy storage research.However,achieving both me...To meet the growing needs of flexible and wearable electronics,stretchable energy storage devices—especially supercapacitors(SCs)—have become a key focus in advanced energy storage research.However,achieving both mechanical stretchability and high capacitance in SC still faces great challenges,and the crucial factors lie in creating superior electrode materials that exhibit high electrochemical performance as well as excellent mechanical stretchability.Covalent organic frameworks(COFs)possess considerable potential as electrode materials for SCs by virtue of stable organic frameworks,open channels and designable functional groups.Nevertheless,their applications in flexible SCs are greatly hindered by their rigid characteristics.Here a novel COFs@conductive polymer hydrogels(CPHs)@poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)complexes,which integrate the pseudocapacitance of PDITAPA COF,mechanical stretchability of hydrogels and high conductivity of PEDOT:PSS,has been developed as stretchable electrode of SCs.Physically cross-linked PEDOT nanofibers,with their interlinked and entangled architecture,collectively boost mechanical,electrical,and electrochemical performance.The COFs@CPHs@PEDOT:PSS simultaneously demonstrates outstanding mechanical stretchability,high electrical behaviors,and superior swelling characteristics.The resulting SC exhibits advantages of simple structures,facile assembly processes,high specific capacitance,excellent cycling stability,and arbitrary deformation,which holds great application prospects for wearable electronic products.Owing to its uncomplicated structure,ease of production,high energy storage capacity,robust cycling performance,and adaptability to deformation,this fabricated SC is well-suited for next-generation wearable technologies.展开更多
Ufmylation is an ubiquitin-like post-translational modification characterized by the covalent binding of mature UFM1 to target proteins.Although the consequences of ufmylation on target proteins are not fully understo...Ufmylation is an ubiquitin-like post-translational modification characterized by the covalent binding of mature UFM1 to target proteins.Although the consequences of ufmylation on target proteins are not fully understood,its importance is evident from the disorders resulting from its dysfunction.Numerous case reports have established a link between biallelic loss-of-function and/or hypomorphic variants in ufmylation-related genes and a spectrum of pediatric neurodevelopmental disorders.展开更多
The influence of bond valence on bond covalence in Lal-xCaxCrO3(x = 0.0, 0.1, 0.2, 0.3) has been studied by using semi empirical method. This method is the extortion of the dialectic description theory proposed by Phi...The influence of bond valence on bond covalence in Lal-xCaxCrO3(x = 0.0, 0.1, 0.2, 0.3) has been studied by using semi empirical method. This method is the extortion of the dialectic description theory proposed by Phillips, Van Vetches, Levine and Tanaka (PVLT). In the calculation of bond valence, two schemes were adopted. The first is the equal-valence scheme, and the second is Bond Valence Sums (BVS) scheme. Bath schemes suggest that for the title compound bond covalence be mainly influenced by bond valence, and insensitive to the Ca doping level. Generally speaking, larger bond valences usually result in higher bond covalence's.展开更多
Lithium-rich layered oxides (LLOs) are increasingly recognized as promising cathode materials for nextgeneration high-energy-density lithium-ion batteries (LIBs).However,they suffer from voltage decay and low initial ...Lithium-rich layered oxides (LLOs) are increasingly recognized as promising cathode materials for nextgeneration high-energy-density lithium-ion batteries (LIBs).However,they suffer from voltage decay and low initial Coulombic efficiency (ICE) due to severe structural degradation caused by irreversible O release.Herein,we introduce a three-in-one strategy of increasing Ni and Mn content,along with Li/Ni disordering and TM–O covalency regulation to boost cationic and anionic redox activity simultaneously and thus enhance the electrochemical activity of LLOs.The target material,Li_(1.2)Ni_(0.168)Mn_(0.558)Co_(0.074)O_(2)(L1),exhibits an improved ICE of 87.2%and specific capacity of 293.2 mA h g^(-1)and minimal voltage decay of less than 0.53 m V cycle-1over 300 cycles at 1C,compared to Li_(1.2)Ni_(0.13)Mn_(0.54)Co_(0.13)O_(2)(Ls)(274.4 mA h g^(-1)for initial capacity,73.8%for ICE and voltage decay of 0.84 mV/cycle over 300 cycles at 1C).Theoretical calculations reveal that the density of states (DOS) area near the Fermi energy level for L1 is larger than that of Ls,indicating higher anionic and cationic redox reactivity than Ls.Moreover,L1 exhibits increased O-vacancy formation energy due to higher Li/Ni disordering of 4.76%(quantified by X-ray diffraction Rietveld refinement) and enhanced TM–O covalency,making lattice O release more difficult and thus improving electrochemical stability.The increased Li/Ni disordering also leads to more Ni^(2+)presence in the Li layer,which acts as a pillar during Li+de-embedding,improving structural stability.This research not only presents a viable approach to designing low-Co LLOs with enhanced capacity and ICE but also contributes significantly to the fundamental understanding of structural regulation in high-performance LIB cathodes.展开更多
基金supported by Young Project of Education Department in Guizhou Province(No.2022099)the Natural Science Special of Guizhou University(No.X202220 Special Post A)the National Natural Science Foundation of China(Grant No.22208071)。
文摘The persistent stability of ruthenium dioxide(RuO_(2))in acidic oxygen evolution reactions(OER)is compromised by the involvement of lattice oxygen(LO)and metal dissolution during the OER process.Heteroatom doping has been recognized as a viable strategy to foster the stability of RuO_(2)for acidic OER applications.This study presented an ion that does not readily gain or lose electrons,Ba^(2+),into RuO_(2)(Ba-RuO_(2))nanosheet(NS)catalyst that increased the number of exposed active sites,achieving a current density of 10 mA/cm^(2)with an overpotential of only 229 mV and sustaining this output for over 250 h.According to density functional theory(DFT)and X-ray absorption spectroscopy,Ba doping resulted in a longer Ru-O bond length,which in turn diminished the covalency of the bond.This alteration curtailed the involvement of LO and the dissolution of ruthenium(Ru),thereby markedly improving the durability of the catalyst over extended periods.Additionally,attenuated total reflectance-surface enhanced infrared absorption spectroscopy analysis substantiated that the OER mechanism shifted from a LO-mediated pathway to an adsorbate evolution pathway due to Ba doping,thereby circumventing Ru over-oxidation and further enhancing the stability of RuO_(2).Furthermore,DFT findings uncovered that Ba doping optimizes the adsorption energy of intermediates,thus enhancing the OER activity in acidic environments.This study offers a potent strategy to guide future developments on Ru-based oxide catalysts'stability in an acidic environment.
基金financial support from the National Natural Science Foundation of China(22478278,22308246)the Central Government Guides the Local Science and Technology Development Special Fund(YDZJSX20231A015)the Fundamental Research Program of Shanxi Province(202203021212266)。
文摘Ruthenium dioxide(RuO_(2))is one of the most promising acidic oxygen evolution reaction(OER)catalysts to replace the expensive and prevalent iridium(Ir)-based materials.However,the lattice oxygen oxidation induced Ru dissolution during OER compromises the activity and stability.Amorphous materials have been identified as a viable strategy to promote the stability of RuO_(2)in acidic OER applications.This study reported a nanoporous amorphous-rich RuMnO_(x)(A-RuMnO_(x))aerogel for efficient and stable acidic OER.Compared with highly crystalline RuMnO_(x),the weakened Ru–O covalency of A-RuMnO_(x)by forming amorphous structure is favorable to inhibiting the oxidation of lattice oxygen.Meanwhile,this also optimizes the electronic structure of Ru sites from overoxidation and reduces the reaction energy barrier of the rate-determining step.As a result,A-RuMnO_(x)aerogel exhibits an ultra-low overpotential of 145 mV at 10 mA cm^(-2)and durability exceeding 100 h,as well as high mass activity up to 153 mA mg^(-1)_(Ru)at 1.5 V vs.reversible hydrogen electrode(RHE).This work provides valuable guidance for preparing highly active and stable Ru-based catalysts for acidic OER.
基金the National Key Research and Development Program of China(2024YFB4106400,2024YFB4106401)the National Natural Science Foundation of China(22025502,U23A20552)。
文摘The copper-based electrocatalysts feature attractive potentials of converting CO_(2)into multi-carbon(C_(2+))products,while the instability of Cu-O often induces the reduction of Cu^(+)/Cu^(0) catalytic sites at the cathode and refrains the capability of stable electrolysis especially at high powers.In this work,we developed an Erbium(Er)oxide-modified Cu(Er-O-Cu)catalyst with enhanced covalency of Cu-O and more stable active sites.The f-p-d coupling strengthens the covalency of Cu-O,and the stability of Cu^(+)sites under electroreduction condition is critical for promoting the C-C coupling and improving the C_(2+)product selectivity.As a result,the Er-O-Cu sites exhibited a high Faradaic efficiency of C_(2+)products(FEC_(2+))of 86%at 2200 mA cm^(-2),and a peak partial current density of|j_(C2+)|of 1900 mA cm^(-2),comparable to the best reported values for the CO_(2)-to-C_(2+)electroreduction.The CO_(2)electrolysis by the Er-O-Cu sites was further scaled up to 100 cm^(2)to achieve high-power(~200 W)electrolysis with ethylene production rate of 16 mL min^(-1).
基金financially supported by the Nature Science Foundation of Hubei Province of China(No.2024AFB754)the start-up research funds from Wuhan Institute of Technology(No.K202201)
文摘Transition metal oxides have garnered significant attention as electrocatalysts for the oxygen reduction reaction(ORR)and the oxygen evolution reaction(OER).However,their sluggish reaction kinetics and poor stability hinder commercial applications.Herein,we report the synthesis of a bimetallic cobalt manganese oxide,Co_(0.99)Mn_(2.01)O_(4)(CMO),synthesized via a hydrothermal technique,which serves as a highly efficient bifunctional ORR/OER electrocatalyst owing to its impressive halfwave potential of 0.767 V and low overpotential of 1.677 V at 10 mA cm^(-2).Theoretical calculations revealed that the d-band centers of Co 3d and Mn 3d in CMO,located at tetrahedral and octahedral sites,are positioned near the Fermi level,facilitating the adsorption of electrocatalytic intermediates.Furthermore,the distance between the Co 3d and O 2p band centers in CMO is smaller than that in Co_(3)O_(4),and the distance between the Mn 3d and O 2p band centers in CMO is shorter than that in Mn_(2)O_(3),indicating that the Co–O and Mn–O bonds in CMO exhibit greater covalency,significantly enhancing ORR/OER activity.Notably,CMO serves as an advanced air electrode material for rechargeable zinc-air batteries(ZABs),demonstrating improved charge–discharge performance with a low voltage gap of 0.87 V at 5 mA cm^(-2),high peak power density of 124 mW cm^(-2),and excellent cycle stability of over 540 h at 5 mA cm^(-2).This superior ORR/OER activity,combined with the simple material combination,makes CMO a promising catalyst for rechargeable ZABs.
文摘The optical absorption spectra of the covalent crystals ZnX(X=S,Se) doped with Co 2+ are studied using the double covalency factors,which considers the anisotropic distortion of e g and t 2g orbits for d electron.When the paramagnetic g factor is calculated,the contributions of the spin orbit coupling from the ligand ions are taken into account besides that from the central ion,which is the double ξ model.The calculated results indicate that the theoretical values coincide with the experimental values very well.This suggests that the method presented in this paper could be more valid to some strongly covalent crystals.
文摘High‐entropy materials are emerging electrocatalysts by integrating five or more elements into one single crystallographic phase to optimize the electronic structures and geometric environments.Here,a rocksalt‐type high‐entropy oxide Mg_(0.2)Co_(0.2)Ni_(0.2)Cu_(0.2)Zn_(0.2)O(HEO)is developed as an electrocatalyst towards the oxygen evolution reaction(OER).The obtained HEO features abundant cation and oxygen vacancies originating from the lattice mismatch of neighboring metal ions,together with enlarged Co/Ni‒O covalency due to the introduction of less electronegative Mg and Zn.As a result,the HEO exhibits superior intrinsic OER activities,delivering a turnover frequency(TOF)15 and 84 folds that of CoO and NiO at 1.65 V,respectively.This study provides a mechanistic understanding of the enhanced OER on HEO and demonstrates the potential of high‐entropy strategy in developing efficient oxygen electrocatalysts by elaborately incorporating low‐cost elements with lower electronegativity.
文摘The relationship between bond valence and bond covalency in RMn2O5 (R = La, Pr, Nd.Sm, Eu) has been investigated by a semiempirical method. This method is the generalization of thedielectric description theory of Phillips. Van Vechten, Levine and Tanaka scheme. The resultsindicate that larger valences usually result in higher bond covalencies, in good agreement with thepoint that the excess charge in the bonding region is the origin of formation of bond covalency.Other factors, such as oxidation state of elements, only make a small contribution to bondcovalency.
基金supported by the NationallNaturallScience Foundation of China(51832004,51521001,51872218)the NationallKey Research and Development Program of China(2016YFA0202603)+3 种基金the Programme of Introducing Talents of Discipline to Universities(B17034)the Yellow Crane Talent(Science&Technology)Program of Wuhan CityFoshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT2020-003)the FundamentallResearch Funds for the CentrallUniversities(195101005)。
文摘Exploring efficient,cost-effective,and durable electrocatalysts for electrochemical oxygen evolution reaction(OER)is pivotal for the large-scale application of water electrolysis.Recent advance has demonstrated that the activity of electrocatalysts exhibits a strong dependence on the surface electronic structure.Herein,a series of ultrathin metal silicate hydroxide nanosheets(UMSHNs)M_(3)Si_(2)O_(5)(OH)_(4)(M=Fe,Co,and Ni)synthesized without surfactant are introduced as highly active OER electrocatalysts.Cobalt silicate hydroxide nanosheets show an optimal OER activity with overpotentials of 287 and 358 m V at 1 and 10 m A cm^(-2),respectively.Combining experimental and theoretical studies,it is found that the OER activity of UMSHNs is dominated by the metal-oxygen covalency(MOC).High OER activity can be achieved by having a moderate MOC as reflected by aσ^(*)-orbital(e_(g))filling near unity and moderate[3d]/[2p]ratio.Moreover,the UMSHNs exhibit favorable chemical stability under oxidation potential.This contribution provides a scientific guidance for further development of active metal silicate hydroxide catalysts.
基金supported by the National Natural Science Foundation of China(U22B20143,U24A20546,22478121)the Shanghai Municipal Science and Technology Major Project+4 种基金the Science and Technology Commission of Shanghai Municipality(22dz1205900)the Fundamental Research Funds for the Central Universities(JKD01241702)the Japan Society for the Promotion of Science(JSPS)KAKENHI(JP23K13703,JP24K23069)the Ensemble Grants for Early Career Researchers 2024Strategic Priority Research Program of the Chinese Academy of Sciences(XDA 0400000)。
文摘The increasing demand for green hydrogen production requires the development of advanced ruthenium(Ru)-based oxide catalysts for the anodic oxygen evolution reaction(OER).Here,we report the development of a Ga-doped RuO_(2)catalyst(GaRuO_(2))that demonstrates enhanced OER performance attributed to modulated Ru-O bond covalency.The fully occupied 3d orbital of Ga stabilizes its oxidation state during OER,while its atomic radius,similar to Ru,helps maintain the initial crystal lattice structure upon doping.In-situ characterization,kinetic analysis and theoretical calculations reveal that the weakened Ru-O bond covalency lowers the energy barriers for *OH and *OOH formation,thus contributing to an enhanced OER performance.The resultant Ga-RuO_(2)achieves a current density of 10 mA cm^(-2) at a low overpotential of 203 mV and demonstrates durable operation for 500 h in acid.This work provides valuable insights into the electronic structure engineering of Ru-based catalysts for practical water electrolysis applications.
基金support from the National Natural Science Foundation of China(Nos.21878202,21975175,and U1932119)the research project supported by Shanxi Scholarship Council of China(No.2017-041)+1 种基金the Natural Science Foundation of Shanxi Province(No.201801D121052)the National Key Basic Research Program of China(No.2017YFA0403402).
文摘Oxygen evolution reaction(OER)is crucial for hydrogen production as well as other energy storage technologies.CoFe-layered double hydroxide(CoFe-OH)has been widely considered as one of the most efficient electrocatalysts for OER in basic aqueous solution.However,it still suffers from low activity in neutral electrolyte.This paper describes partially oxidized CoFe-OH(PO-CoFe-OH)with enhanced covalency of M-O bonds and displays enhanced OER performance under mild condition.Mechanism studies reveal the suitably enhanced M-O covalency in PO-CoFe-OH shifts the OER mechanism to lattice oxygen oxidation mechanism and also promotes the rate-limiting deprotonation,providing superior OER performance.It just requires the overpotentials of 186 and 365 mV to drive the current density densities of 1 and 10 mA·cm^(-2) in 0.1 M KHCO_(3) aqueous solution(pH=8.3),respectively.It provides a new process for rational design of efficient catalysts for water oxidation in mild conditions.
基金supported by the National Natural Science Foundation of China(51978178,52270064,and 51521006)the Department of Science and Technology of Guangdong Province of China(2022A1515010226)+3 种基金the Program for Innovative Research Teams of Guangdong Higher Education Institutes of China(2021KCXTD043)Key Laboratory of Petrochemical Pollution Control of Guangdong Higher Education Institutes(KLGHEI 2017KSYS004)the Science and Technology Innovation Program of Hunan Province of China(2021RC2058)the Startup Fund of Guangdong University of Petrochemical Technology(2018rc63)。
文摘Oxidative desulfurization(ODS)is a promising technology to produce clean fuel with requiring superior catalysts to lower kinetic barriers.Although most ODS catalysts are based on crystalline transition-metal oxides(TMOs),extraordinary activity also can be achieved with amorphous TMOs.However,the origin of the remarkable catalytic activity of the amorphous TMOs remains greatly ambiguous.Here,we found the crucial role of Mo–O covalency in ruling the intrinsic catalytic activity of amorphous molybdenum oxides(MoO_(x)).Experimental and theoretical analysis indicated that the nonequivalent connectivity in the amorphous structure strongly enhanced Mo–O covalency,thereby increasing the content of electrophilic oxygen and nucleophilic molybdenum to favor the MoO_(x)–H_(2)O_(2) interaction.With the boosted Mo–O covalency to improve the flexibility of the charge state,the amorphous MoO_(x)-based composite catalyst(PE-MoO_(x)/S-0.05)exhibited outstanding catalytic activity for ODS of fuel oil.The turnover frequency(TOF)value of the catalyst(18.63 h^(-1))was almost an order of magnitude higher than that of most reported crystalline MoO_(x)/molecular sieve composite catalysts.The in-depth understanding of the origin of the amorphous TMOs activity for ODS provides a valuable reference for developing ODS catalysts.
基金Project supported by the National Natural Science Foundation of China （No. 50472050） and the Program for New Century Excellent Talents in University and the Foundation for the Author of National Excellent Doctoral Dissertation of China （No. 200434）.
文摘It was found that the highly covalent nature of the metal-ligand interactions in the Fe-S cluster clearly played an important role in determining the reactivity of the sites. A semi-empirical model, based on the Phillips theory of bonding was developed for quantitative explanation of covalency in Fe-S cluster, showing that Mossbauer spectroscopy and electronic absorption spectroscopy provided the direct experimental probe of covalency of Fe-S4 clusters.
基金supported by the Nanjing Second Hospital talent lifting project(No.RCZD23001)the Jiangsu Province traditional Chinese medicine science and technology development general program(No.MS2023063)+1 种基金Medical Science and Technology Development Foundation,Nanjing Department of Health(No.ZKX20033)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX25_0240).
文摘Enhancing the activity of fragile enzymes is greatly useful for various purposes,including fabrication of enzyme-based immunosensors.Herein,we report a defect-engineering strategy for encapsulating enzymes within covalent organic frameworks(COFs),enabling the resulting immobilized enzymes with excellent catalytic activity and stability to construct high performance immunosensors.In this design,by consciously introducing monoaldehyde ligands into the imine-linked COFs structure,we have precisely customized the structural defects to improve enzyme loading capacity and conformational stability.Defect-engineering interaction modulation between enzymes and COFs drives the enhancement of catalytic performance.Compared to the pristine COFs,the enzyme@defective COFs composites with optimally tuned catalytic performance exhibit a 4.49-fold enhancement in enzymatic activity.Furthermore,it is demonstrated that the stable skeletons of COFs provide exceptional protection for the enzymes against external perturbations.Thereafter,the optimized enzyme@defective COFs are employed to fabricate immunosensor.We have successfully established a detection method for prostate-specific antigen(PSA),achieving a low detection limit of 0.09 ng/mL.More importantly,the developed immunosensor has successfully distinguished the prostate cancer patients from healthy individuals.This work establishes a novel paradigm for enzyme immobilization,ultimately empowering the construction of a PSA immunosensor with high sensitivity,remarkable operational stability,and great clinical application potential.
基金financially supported by the National Natural Science Foundation of China(No.22508360)Zhejiang Provincial Natural Science Foundation of China(No.QN26B060028)+1 种基金the National Key Research and Development Program Nanotechnology Specific Project(No.2020YFA0210900)Innovative Team Project of Guang-dong Ordinary University(No.2019KCXTD002).
文摘Constructing catalysts featuring an ordered structure,stable performance,and uniformly dispersed catalytic sites is vital for the epoxidation of small-molecular olefins.Here,we design catalysts by tracing the oxidationprocess origin and synthesize a series of highly dispersed metal porphyrin-based covalent organic frameworks(COFs)materials.The aim is to efficiently oxidize the C-H bonds of cumene by air to in-situ generate organic peroxides at a safe concentration,and integrate the multi-step oxidation method of cumene in industry into a one-step method for olefins’epoxidation.The carbonyl-ruthenium COF(Ru-COF-1)exhibits excellent performance,with 98% epoxide selectivity,1221.77 h^(-1) productivity,and over 95% selectivity after 9 cycles for 1-hexene.Analysis of structure-properties-catalytic relationships of Ru-COF-1 shows that,compared with Ru-porphyrins and metal-free COFs,the enhanced reaction performance mainly results from Ru metal introduction,which promotes benzylic proton transfer in cumene.Besides,Ru-COF-1’s porous,ordered structure aids oxygen enrichment,forming active peroxy radicals with the cumene carboncentered radicals formed on the catalyst surface.Ru-H sites then accelerate active oxygen transfer from peroxy radicals,enabling olefin tandem epoxidation.Density functional theory(DFT)calculations verify the reaction mechanism,and this work offers a reference for the design of catalysts for the green,safe,and efficient oxidation of olefins.
基金supported by National Natural Science Foundation of China(No.52103044)Double First-Class Initiative University of Science and Technology of China(KY2400000037)the Young Talent Programme(GG2400007009).
文摘Conductive elastomers combining micromechanical sensitivity,lightweight adaptability,and environmental sustainability are critically needed for advanced flexible electronics requiring precise responsiveness and long-term wearability;however,the integration of these properties remains a significant challenge.Here,we present a biomass-derived conductive elastomer featuring a rationally engineered dynamic crosslinked network integrated with a tunable microporous architecture.This structural design imparts pronounced micromechanical sensitivity,an ultralow density(~0.25 g cm^(−3)),and superior mechanical compliance for adaptive deformation.Moreover,the unique micro-spring effect derived from the porous architecture ensures exceptional stretchability(>500%elongation at break)and superior resilience,delivering immediate and stable electrical response under both subtle(<1%)and large(>200%)mechanical stimuli.Intrinsic dynamic interactions endow the elastomer with efficient room temperature self-healing and complete recyclability without compromising performance.First-principles simulations clarify the mechanisms behind micropore formation and the resulting functionality.Beyond its facile and mild fabrication process,this work establishes a scalable route toward high-performance,sustainable conductive elastomers tailored for next-generation soft electronics.
基金granted by the National Natural Science Foundation of China(Nos.52533008,21835003,62274097,and 62004106)National Key Research and Development Program of China(Nos.2024YFB3612500,2024YFB3612600,and 2023YFB3608900)+2 种基金Basic Research Program of Jiangsu Province(No.BK20243057)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX25_1213)the Natural Science Foundation of Nanjing Universityof Posts and Telecommunications(No.NY225135).
文摘To meet the growing needs of flexible and wearable electronics,stretchable energy storage devices—especially supercapacitors(SCs)—have become a key focus in advanced energy storage research.However,achieving both mechanical stretchability and high capacitance in SC still faces great challenges,and the crucial factors lie in creating superior electrode materials that exhibit high electrochemical performance as well as excellent mechanical stretchability.Covalent organic frameworks(COFs)possess considerable potential as electrode materials for SCs by virtue of stable organic frameworks,open channels and designable functional groups.Nevertheless,their applications in flexible SCs are greatly hindered by their rigid characteristics.Here a novel COFs@conductive polymer hydrogels(CPHs)@poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)complexes,which integrate the pseudocapacitance of PDITAPA COF,mechanical stretchability of hydrogels and high conductivity of PEDOT:PSS,has been developed as stretchable electrode of SCs.Physically cross-linked PEDOT nanofibers,with their interlinked and entangled architecture,collectively boost mechanical,electrical,and electrochemical performance.The COFs@CPHs@PEDOT:PSS simultaneously demonstrates outstanding mechanical stretchability,high electrical behaviors,and superior swelling characteristics.The resulting SC exhibits advantages of simple structures,facile assembly processes,high specific capacitance,excellent cycling stability,and arbitrary deformation,which holds great application prospects for wearable electronic products.Owing to its uncomplicated structure,ease of production,high energy storage capacity,robust cycling performance,and adaptability to deformation,this fabricated SC is well-suited for next-generation wearable technologies.
文摘Ufmylation is an ubiquitin-like post-translational modification characterized by the covalent binding of mature UFM1 to target proteins.Although the consequences of ufmylation on target proteins are not fully understood,its importance is evident from the disorders resulting from its dysfunction.Numerous case reports have established a link between biallelic loss-of-function and/or hypomorphic variants in ufmylation-related genes and a spectrum of pediatric neurodevelopmental disorders.
基金Project supported by Laboratory of Rare Earth Chemistry and Physics and Applied Chemistry Research Centre of Changchun, China
文摘The influence of bond valence on bond covalence in Lal-xCaxCrO3(x = 0.0, 0.1, 0.2, 0.3) has been studied by using semi empirical method. This method is the extortion of the dialectic description theory proposed by Phillips, Van Vetches, Levine and Tanaka (PVLT). In the calculation of bond valence, two schemes were adopted. The first is the equal-valence scheme, and the second is Bond Valence Sums (BVS) scheme. Bath schemes suggest that for the title compound bond covalence be mainly influenced by bond valence, and insensitive to the Ca doping level. Generally speaking, larger bond valences usually result in higher bond covalence's.
基金National Natural Science Foundation of China (No.52202046)Natural Science Foundation of Shaanxi Province (No.2021JQ-034)。
文摘Lithium-rich layered oxides (LLOs) are increasingly recognized as promising cathode materials for nextgeneration high-energy-density lithium-ion batteries (LIBs).However,they suffer from voltage decay and low initial Coulombic efficiency (ICE) due to severe structural degradation caused by irreversible O release.Herein,we introduce a three-in-one strategy of increasing Ni and Mn content,along with Li/Ni disordering and TM–O covalency regulation to boost cationic and anionic redox activity simultaneously and thus enhance the electrochemical activity of LLOs.The target material,Li_(1.2)Ni_(0.168)Mn_(0.558)Co_(0.074)O_(2)(L1),exhibits an improved ICE of 87.2%and specific capacity of 293.2 mA h g^(-1)and minimal voltage decay of less than 0.53 m V cycle-1over 300 cycles at 1C,compared to Li_(1.2)Ni_(0.13)Mn_(0.54)Co_(0.13)O_(2)(Ls)(274.4 mA h g^(-1)for initial capacity,73.8%for ICE and voltage decay of 0.84 mV/cycle over 300 cycles at 1C).Theoretical calculations reveal that the density of states (DOS) area near the Fermi energy level for L1 is larger than that of Ls,indicating higher anionic and cationic redox reactivity than Ls.Moreover,L1 exhibits increased O-vacancy formation energy due to higher Li/Ni disordering of 4.76%(quantified by X-ray diffraction Rietveld refinement) and enhanced TM–O covalency,making lattice O release more difficult and thus improving electrochemical stability.The increased Li/Ni disordering also leads to more Ni^(2+)presence in the Li layer,which acts as a pillar during Li+de-embedding,improving structural stability.This research not only presents a viable approach to designing low-Co LLOs with enhanced capacity and ICE but also contributes significantly to the fundamental understanding of structural regulation in high-performance LIB cathodes.
