Theory-driven designed TiO_(2)@MoO_(2)heterojunction:Balanced crystallinity and nanostructure toward desirable kinetics and highrate sodium-ion storage

Sodium-ion batteries(SIBs)are promising candidates for large-scale energy storage due to their cost effectiveness and the unlimited availability of sodium.However,there remains a need for the rational design of better anodic materials than are currently available,as these materials are critical for the sodium-ion storage process.In this work,theoretical calculations were performed to design a conceptually novel TiO_(2)@MoO_(2)heterojunction(TMH)anode that was expected to exhibit better electrochemical performance than current anodes.The TMH anode was fabricated via a facile and cost-effective method,and the results of in-depth sodium-ion-storage performance and reaction kinetics analyses indicate that it exhibited an excellent rate capability and enhanced pseudocapacitive response,due to its high crystallinity.This electrochemical performance was superior to that of previously reported anodic materials,confirming the accuracy of the theoretical calculations.Destruction of TMH’s nanostructure at high temperatures resulted in a decrease in its electrochemical performance,indicating the key role played by the nanostructure in TMH’s ability to store sodium ions.This study demonstrates that integration of theoretical predictions with experimental investigations offers insights into how materials’crystallinity and nanostructure affect their pseudocapacitive sodiumion storage capabilities,which will help to guide the rational design of effective anodic materials for SIBs.

Theory-Driven Design of Electrocatalysts for the Two-Electron Oxygen Reduction Reaction Based on Dispersed Metal Phthalocyanines

The two-electron electrochemical reduction of oxygen is an appealing approach to produce hydrogen peroxide.Metal and heteroatom-doped carbon(M–X/C)materials have recently been recognized as compelling catalysts for this process,but their performance improvement is generally hindered by the ill-defined structures of active sites.Herein,we demonstrate a theory-driven design of catalysts for oxygen reduction reactions based on molecularly dispersed electrocatalysts(MDEs)with metal phthalocyanines on carbon nanotubes.Density functional theory calculations suggest that nickel phthalocyanine(NiPc)favors the formation of*H_(2)O_(2) over*O,thus acting as a selective catalyst for peroxide production.NiPc MDE shows high peroxide yields of∼83%,superior to the aggregated NiPc and pyrolyzed Ni–N/C catalysts.The performance is further enhanced by the introduction of the cyano group(CN).NiPc–CN MDE exhibits∼92%peroxide yields and good stability.Our studies provide a new perspective for the development of heterogeneous electrocatalysts for hydrogen peroxide production from metal macrocyclic complexes.

Revealing the Role of d Orbitals of Transition-Metal-Doped Titanium Oxide on High-Efficient Oxygen Reduction

Precise catalysis is critical for the high-quality catalysis industry.However,it remains challenging to fundamentally understand precise catalysis at the atomic orbital level.Herein,we propose a new strategy to unravel the role of specific d orbitals in catalysis.The oxygen reduction reaction(ORR)catalyzed by atomically dispersed Pt/Co-doped Ti_(1−x)O_(2) nanosheets(Pt_(1)/Co_(1)-Ti_(1−x)O_(2))is used as a model catalysis.The z-axis d orbitals of Pt/Co-Ti realms dominate the O2 adsorption,thus triggering ORR.In light of orbital-resolved analysis,Pt_(1)/Co_(1)-Ti_(1−x)O_(2) is experimentally fabricated,and the excellent ORR catalytic performance is further demonstrated.Further analysis reveals that the superior ORR performance of Pt_(1)-Ti_(1−x)O_(2) to Co_(1)-Ti_(1−x)O_(2) is ascribed to stronger activation of Ti by Pt than Co via the d-d hybridization.Overall,this work provides a useful tool to understand the underlying catalytic mechanisms at the atomic orbital level and opens new opportunities for precise catalyst design.