Combining descriptor-based analyses and mean-field modeling of the electrochemical interface to comprehend trends of catalytic processes at the solid/liquid interface

Electrocatalysis is undergoing a renaissance due to its central importance for a sustainable energy economy,relying on green(electro-)chemical processes to harvest,convert,and store energy.Theoretical considerations by electronic structure methods are key to identify potential material motifs for electrocatalytic processes at the solid/liquid interface.Most commonly,heuristic concepts in the realm of materials screening by the compilation of volcano plots are used,which rely on a plethora of simplifications and approximations of the complex electrochemical interface.While the investigation of the catalytic processes at the solid/liquid interface mainly relies on descriptor-based approaches,in the present future article it is discussed that the inclusion of the liquid part of the interface by mean-field models is crucial to elevate screening approaches to the next level.

Combined DFT and experiment:Stabilizing the electrochemical interfaces via boron Lewis acids

The incorporation of boron into carbon material can significantly enhance its capacity performances.However,the origin of the promotion effect of boron doping on electrochemical performances is still unclear,in part due to the inadequate exposure of boron configurations resulting from the complexity of traditional carbon materials.To overcome this issue,herein,a series of boron-doped graphene with highly-exposed boron configurations are prepared by tuning annealing temperature.Then the correlation between boron configurations and the electrochemical performances is investigated.The combination of density-functional theory(DFT)computation and NH3-TPD/Py-FTIR indicates that the BCO_(2)configuration formed on the surface of graphene is easier to accept lone-pair electrons than BC_(2)O and BC_(3)configurations due to the stronger Lewis acidity.Such an electronic structure can effectively reduce the number of unstable electron donors and stabilize the electrochemical interface,which is proved by NMR,and critical for improving the electrochemical performances.Further experiments confirm that the optimized BG800 with the largest amount of BCO_(2)configuration presents ultralow leak current,improved cyclic stability,and better rate performance in SBPBF4/PC.This work would provide an insight into the design of high-performance boron-doped carbon materials towards energy storage.

Constant charge method or constant potential method:Which is better for molecular modeling of electrical double layers?

In molecular modeling of electrical double layers(EDLs),the constant charge method(CCM)is prized for its computational efficiency but cannot maintain electrode equipotentiality like the more resourceintensive constant potential method(CPM),potentially leading to inaccuracies.In certain scenarios,CCM can yield results identical to CPM.However,there are no clear guidelines to determine when CCM is sufficient and when CPM is required.Here,we conduct a series of molecular simulations across various electrodes and electrolytes to present a comprehensive comparison between CCM and CPM under different charging modes.Results reveal that CCM approximates CPM effectively in capturing equilibrium EDL and current-driven dynamics in open electrode systems featuring ionic liquids or regular concentration aqueous electrolytes,while CPM is indispensable in scenarios involving organic and highly concentrated aqueous electrolytes,nanoconfinement effects,and voltage-driven dynamics.This work helps to select appropriate methods for modeling EDL systems,prioritizing accuracy while considering computationalefficiency.

Molecular-level investigation on electrochemical interfaces by Raman spectroscopy

The structure and dynamics of electrode/liquid interfaces play an increasingly important role in electrochemistry. Raman spectroscopy is capable of providing detailed structural information at molecular level and new insight into the interfacial structure, adsorption, reaction, electrocatalysis and corrosion. In this account we will summarize some progresses of surface Raman spectroscopy in the study of electrochemical interfaces, mainly based on our group's work, laying emphasis on the detection sensitivity, spectral resolution, time resolution and spatial resolution as well as the hyphenated technique.

High entropy spinel oxide for efficient electrochemical oxidation of ammonia

Ammonia has emerged as a promising energy carrier owing to its carbon neutral content and low expense in long-range transportation.Therefore,development of a specific pathway to release the energy stored in ammonia is therefore in urgent demand.Electrochemical oxidation provides a convenient and reliable route to attain efficient utilization of ammonia.Here,we report that the high entropy(Mn,Fe,Co,Ni,Cu)_(3)O_(4)oxides can achieve high electrocatalytic activity for ammonia oxidation reaction(AOR)in non-aqueous solutions.The AOR onset overpotential of(Mn,Fe,Co,Ni,Cu)_(3)O_(4)is 0.70 V,which is nearly 0.2 V lower than that of their most active single metal cation counterpart.The mass spectroscopy study reveals that(Mn,Fe,Co,Ni,Cu)_(3)O_(4)preferentially oxidizes ammonia to environmentally friendly diatomic nitrogen with a Faradic efficiency of over 85%.The Xray photoelectron spectroscopy(XPS)result indicates that the balancing metal d-band of Mn and Cu cations helps retain a longlasting electrocatalytic activity.Overall,this work introduces a new family of earth-abundant transition metal high entropy oxide electrocatalysts for AOR,thus heralding a new paradigm of catalyst design for enabling ammonia as an energy carrier.

Universal lithiophilic interfacial layers towards dendrite-free lithium anodes for solid-state lithium-metal batteries

Solid-state lithium-metal-batteries(SSLMBs)using garnet Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)as the solid electrolyte are expected to conquer the safety concerns of high energy Li batteries with organic liquid electrolytes owing to its nonflammable nature and good mechanical strength.However,the poor interfacial contact between the Li anode and LLZTO greatly restrains the practical applications of the electrolyte,because large polarization,dendritic Li formation and penetration can occur at the interfaces.Here,an effective method is proposed to improve the wettability of the LLZTO toward lithium and reduce the interfacial resistance by engineering universal lithiophilic interfacial layers.Thanks to the in-situ formed lithiophilic and ionic conductive Co/Li_(2)O interlayers,the symmetric Li/CoO-LLZTO/Li batteries present much smaller overpotential,ultra-low areal specific resistance(ASR,12.3 X cm^(2)),high critical current density(CCD,1.1 mA cm^(-2)),and outstanding cycling performance(1696 h at a current density of 0.3 mA cm^(-2))at 25℃.Besides,the solid-state Li/CoO-LLZTO/LFP cells deliver an excellent electrochemical performance with a high coulombic efficiency of~100%and a long cycling time over 185 times.Surprisingly,the high-voltage(4.6 V)solid state Li/CoO-LLZTO/Li_(1.4)Mn_(0.6)Ni_(0.2)Co_(0.2)O_(2.4)(LMNC622)batteries can also realize an ultra-high specific capacity(232.5 mAh g-1)under 0.1 C at 25℃.This work paves an effective way for practical applications of the dendrite-free SSLMBs.