Regulation of Coordinating Anions around Single Co(Ⅱ)Sites in a Covalent Organic Framework for Boosting CO_(2)Photoreduction

While photocatalytic CO_(2)reduction has been intensively investigated,reports on the influence of anions coordinated to catalytic metal sites on CO_(2)photoreduction remain limited.Herein,different coordinated anions(F^(−),Cl^(−),OAc^(−),and NO_(3)^(−))around single Co sites installed on bipyridine-based three-component covalent organic frameworks(COFs)were synthesized,affording TBD-COF-Co-X(X=F,Cl,OAc,and NO3),for photocatalytic CO_(2)reduction.Notably,the presence of these coordinated anions on the Co sites significantly influences the photocatalytic performance,where TBD-COF-Co-F exhibits superior activity to its counterparts.Combined experimental and theoretical results indicate that the enhanced activity in TBD-COF-Co-F is attributed to its efficient charge transfer,high CO_(2)adsorption capacity,and low energy barrier for CO_(2)activation.This study provides a new strategy for boosting COF photocatalysis through coordinated anion regulation around catalytic metal sites.

Mitigated lattice distortion and oxygen loss of Li-rich layered cathode materials through anion/cation regulation by Ti^(4+)-substitution

Lithium-rich layered cathode material(LLM)can meet the requirement of power lithium-ion energy storage devices due to the great energy density.However,the de/intercalation of Li+will cause the irreversible loss of lattice oxygen and trigger transition metal(TM)ions migrate to Li+vacancies,resulting in capacity decay.Here we brought Ti4+in substitution of TM ions in Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2),which could stabilize structure and expand the layer spacing of LLM.Moreover,optimized Ti-substitution can regulate the anions and cations of LLM,enhance the interaction with lattice oxygen,increase Ni^(3+) and Co^(3+),and improve Mn^(4+) coordination,improving reversibility of oxygen redox activation,maintaining the stable framework and facilitating the Li^(+) diffusion.Furthermore,we found 5%Ti-substitution sample delivered a high discharge capacity of 244.2 mAh/g at 50 mA/g,an improved cycling stability to 87.3%after 100 cycles and enhanced rate performance.Thereby Ti-substitution gives a new pathway to achieve high reversible cycle retention for LLMs.

Electronic structure regulation on layered double hydroxides for oxygen evolution reaction

Oxygen evolution reactions(OERs)as core components of energy conversion and storage technology systems,such as water splitting and rechargeable metal–air batteries,have attracted considerable attention in recent years.Transition metal compounds,particularly layered double hydroxides(LDHs),are considered as the most promising electrocatalysts owing to their unique two-dimensional layer structures and tunable components.However,heir poor intrinsic electrical conductivities and the limited number of active sites hinder their performances.The regulation of the electronic structure is an effective approach to improve the OER activity of LDHs,including cationic and anionic regulation,defect engineering,regulation of intercalated anions,and surface modifications.In this review,we summarize recent advances in the regulation of the electronic structures of LDHs used as electrocatalysts in OERs.In addition,we discuss the effects of each regulation type on OER activities.This review is expected to shed light on the development and design of effective OER electrocatalysts by summarizing various electronic structure regulation pathways and the effects on their catalytic performances.

Lamellar-stacked cobalt-based nanopiles integrated with nitrogen/sulfur co-doped graphene as a bifunctional electrocatalyst for ultralong-term zinc-air batteries

Sluggish oxygen evolution reaction(OER)and oxygen reduction reaction(ORR)kinetics inevitably impede the practical performance of rechargeable zinc-air batteries.Thus,combing the structural designability of transition metal-based electrocatalysts with anionic regulation is highly desired.Herein,mesoporous lamellar-stacked cobalt-based nanopiles with surface-sulfurization modification are elaborately designed and integrated with N/S co-doped graphene to build a robust OER/ORR bifunctional electrocatalyst.The lamellar-stacking mode of mesoporous nanosheets with abundant channels accelerates gas-liquid mass transfer,and partial-sulfurization of cobalt-based matrix surface efficiently improves the intrinsic OER activity.Meanwhile,N/S co-doped graphene further reinforces the ORR active sites while providing a stable conductive skeleton.As expected,this composite electrocatalyst delivers considerable bifunctional activity and stability,with an OER overpotential of 323 m V at 10 m A cm^(-2)and high durability.When applied in zinc-air batteries,remarkable ultralong-term stability over 4000 cycles and a maximum power density of 150.1 m W cm^(-2)are achieved.This work provides new insight into structurecomposition synergistic design of rapid-kinetics OER/ORR bifunctional electrocatalyst for nextgeneration metal-air batteries.

Anion regulating endows core@shell structured hollow carbon spheres@MoSxSe_(2−x)with tunable and boosted microwave absorption performance

Due to the good manipulation of electronic structure and defect,anion regulating should be a promising strategy to regulate the electromagnetic(EM)parameters and optimize the EM wave absorption performances(EMWAPs).In this work,we proposed a facile route for the large-scale production of core@shell structured hollow carbon spheres@MoSxSe_(2−x)(x=0.2,0.6,and 1.0)multicomponent nanocomposites(MCNCs)through a mild template method followed by hydrothermal process.The obtained results revealed that the designed hollow carbon spheres@MoSxSe_(2−x)MCNCs presented the improved sulfur vacancy concentration by regulating the x value from 0.2 to 1.0.The obtained hollow carbon spheres@MoSxSe_(2−x)MCNCs displayed the extraordinary comprehensive EMWAPs because of the introduced abundant defects and excellent interfacial effects.Furthermore,the as-prepared hollow carbon spheres@MoSxSe_(2−x)MCNCs presented the progressively improved comprehensive EMWAPs with the x value increasing from 0.2 to 1.0,which could be explained by their boosted polarization loss abilities and impedance matching characteristics originating from the enhanced sulfur vacancy concentration.Therefore,our findings not only demonstrated that the anion regulating was a promising method to optimize EM parameters and EMWAPs,but also provided a facile route to design the transition metal dichalcogenides-based MCNCs as the much more attractive candidates for highperformance microwave absorbers.