Solid Bi_(2)O_(3)-derived nanostructured metallic bismuth with high formate selectivity for the electrocatalytic reduction of CO_(2)

CO_(2) electrochemical reduction(CO_(2)ER)is an important research area for carbon neutralization.However,available catalysts for CO_(2) reduction are still characterized by limited stability and activity.Recently,metallic bismuth(Bi)has emerged as a promising catalyst for CO_(2) ER.Herein,we report the solid cathode electroreduction of commercial micronized Bi2O3as a straightforward approach for the preparation of nanostructured Bi.At-1.1 V versus reversible hydrogen electrode in a KHCO3aqueous electrolyte,the resulting nanostructure Bi delivers a formate current density of~40 mA·cm^(-2) with a current efficiency of~86%,and the formate selectivity reaches97.6% at-0.78 V.Using nanosized Bi2O3as the precursor can further reduce the primary particle sizes of the resulting Bi,leading to a significantly increased formate selectivity at relatively low overpotentials.The high catalytic activity of nanostructured Bi is attributable to the ultrafine and interconnected Bi nanoparticles in the nanoporous structure,which exposes abundant active sites for CO_(2) electrocatalytic reduction.

Extending the solid solution range of sodium ferric pyrophosphate:Off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)as a novel cathode for sodium‐ion batteries

Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework,cost‐effectiveness,and high energy density.However,the understanding of the crystal structure is scarce and only a limited candidates have been reported so far.In this work,we found for the first time that a continuous solid solution,Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2)(0≤α≤1,could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P_(2)O_(7) unchanged.In particular,a novel off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)is thus proposed,and its structure,energy storage mechanism,and electrochemical performance are extensively investigated to unveil the structure–function relationship.The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g^(−1),a working voltage of 2.9 V(vs.Na^(+)/Na),the retention of 89.2%of the initial capacity after 500 cycles,and enhanced rate capability of 51 mAh g^(−1)at a current density of 1600 mA g^(−1).This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2),offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.

Molten salt electrochemical modulation of Ni/Co nanoparticles onto N-doped carbon for oxygen reduction

Activation of oxygen over non-precious materials has been an imperative task to develop efficient electrochemical energy storage and conversion such as fuel cells and metal-air batteries.Herein,a molten salt electrochemical modulation of metal-nitrogen-carbon based compounds(M–N–C)is achieved.By electrochemical treatment of polydopamine-coated NiCo_(2)O_(4)(NiCo_(2)O_(4)@PDA)in molten Li_(2)CO_(3)-Na_(2)CO_(3)-K_(2)CO_(3)at 500℃,Ni/Co bimetal-nitrogen-carbon catalyst(denoted as Ni/Co@NC)consisting of Ni-Co nanoparticles anchoring on porous nitrogen-doped carbon is constructed and evaluated as electrocatalysts towards the oxygen reduction reaction(ORR).Experimental and calculation results confirm that alloying of Ni-Co and nitrogen doping to carbon enhances the rate-determining transformation of*OH intermediate during ORR.The Ni/Co@NC hence shows an ORR activity comparable with the commercial Pt/C.

Electrochemical conversi on of carb on dioxide in molten salts:In-situ and beyond

The state-of-the-art industry based on carb on-inte nsive energy causes major concerns on energy and environmental sustainability.Carb on n eutrality is now a worldwide con sensus and an imperative task.Efficient capture and/or conversion of carbon dioxide(CO_(2))is key-enabling to achieve carbon neutrality.Challenges of the aforenamed task lie in the chemical inertness of CO_(2) and costly separation of CO_(2) from flue gases.Capture and conversion of CO_(2) on the occasions of gen eration,namely in-situ CO_(2) conversi on,are highly desired.

Access to advanced sodium-ion batteries by presodiation:Principles and applications

Sodium-ion batteries(SIBs)are expected to offer affordability and high energy density for large-scale energy storage system.However,the commercial application of SIBs is hurdled by low initial coulombic efficiency(ICE),continuous Na loss during long-term operation,and low sodium-content of cathode materials.In this scenario,presodiation strategy by introducing an external sodium reservoir has been rationally proposed,which could supplement additional sodium ions into the system and thereby markedly improve both the cycling performance and energy density of SIBs.In this review,the significance of presodiation is initially introduced,followed by comprehensive interpretation on technological properties,underlying principles,and associated approaches,as well as our perspectives on present inferiorities and future research directions.Overall,this contribution outlines a distinct pathway towards the presodiation methodology,of significance but still in its nascent phase,which may inspire the targeted guidelines to explore new chemistry in this field.

Understanding of the sodium storage mechanism in hard carbon anodes

Hard carbon has been regarded as the most promising anode material for sodiumion batteries(SIBs)due to its low cost,high reversible capacity,and low working potential.However,the uncertain sodium storage mechanism hinders the rational design and synthesis of high-performance hard carbon anode materials for practical SIBs.During the past decades,tremendous efforts have been put to stimulate the development of hard carbon materials.In this review,we discuss the recent progress of the study on the sodium storage mechanism of hard carbon anodes,and the effective strategies to improve their sodium storage performance have been summarized.It is anticipated that hard carbon anodes with high electrochemical properties will be inspired and fabricated for large-scale energy storage applications.

Catalytic decomposition of methane to produce hydrogen:A review

The increasing demands of hydrogen and the recent discovery of large reserves of methane have prompted the conversion of methane to hydrogen.The challenges raised by intensive CO_(2) emission from the traditional conversion of methane have provoked emission-free hydrogen production from methane.The catalytic decomposition of methane(CDM) to produce hydrogen and advanced carbon hence comes into consideration due to the short process and environmental benignity.Although many researchers have made considerable progress in CDM research on the laboratory scale,CDM is still in its infancy in industrialization.The history of its development,fundamental mechanisms,and recent research progress in catalysts and catalytic systems are herein highlighted.The problems of catalytic interface degradation are reviewed,focusing on deactivation from coke deposition in the CDM process.The introduction of a liquid phase interface which can in-situ remove carbon products provides a new strategy for this process.Furthermore,the challenges and prospects for future research into novel CDM catalysts or catalyst systems are included.

Interfacial confinement of Ni-V2O3 in molten salts for enhanced electrocatalytic hydrogen evolution

Implementation of non-precious electrocatalysts is key-enabling for water electrolysis to relieve challenges in energy and environmental sustainability. Self-supporting Ni-V2O3 electrodes consisting of nanostrip-like V2O3 perpendicularly anchored on Ni meshes are herein constructed via the electrochemical reduction of soluble NaVO3 in molten salts for enhanced electrocatalytic hydrogen evolution. Such a special configuration in morphology and composition creates a well confined interface between Ni and V2O3. Experimental and Density-Functional-Theory results confirm that the synergy between Ni and V2O3 accelerates the dissociation of H2O for forming hydrogen intermediates and enhances the combination of H*for generating H2.

Controllable conversion of rice husks to Si/C and SiC/C composites in molten salts

Direct conversion of biomass to functional materials is an ideal solution to relieve challenges in environmental and energy sustainability.We herein demonstrate a molten salt thermoelectrolysis of rice husks(RHs)mainly consisting of organic mass and biosilica to achieve high-efficiency and upgraded utilization of both Si and C in RHs.By coupling pyrolysis of organic mass with electrochemical reduction of silica in molten salts,the thermoelectrolysis of RHs in molten CaCl_(2)-NaCl at 800℃ refines the RHs and acidleached RHs to SiC nanowire/C(SiC-NW/C)and Si nanoparticle/C(Si-NP/C),respectively.The present study highlights the molten salt thermoelectrolysis for reclamation of biomass wastes in an affordable and controllable manner.

Induced growth of Fe-N_x active sites using carbon templates

Highly active Fe-N_x sites that effectively improve the performance of non-precious metal electrocatalysts for oxygen reduction reactions（ORRs） are desirable. Herein, we propose a strategy for introducing a carbon template into a melamine/Fe-salt mixture to inductively generate highly active Fe-N_x sites for ORR. Using 57 Fe M？sbauer spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, we studied the structural composition of the Fe and N co-doped carbon catalysts.Interestingly, the results showed that this system not only converted inactive Fe and Fe-carbides into active Fe-N_4 and other Fe-nitrides, but also improved their intrinsic activities.

Synergy of staggered stacking confinement and microporous defect fixation for high‐density atomic Fe^(Ⅱ)‐N_(4)oxygen reduction active sites

The development of high‐performance nonprecious metal catalysts(NPMCs)to supersede Pt‐based catalysts for the oxygen reduction reaction(ORR)in polymer electrolyte membrane fuel cells is highly desirable but remains challenging.In this paper,we present a pyrolysis strategy for spatial confinement and active‐site fixation using iron phthalocyanine(FePc),phthalocyanine(Pc)and Zn salts as precursors.In the obtained carbon‐based NPMC with a hierarchically porous nanostructure of thin‐layered carbon nanosheets,nearly 100%of the total Fe species are Fe^(Ⅱ)‐N_(4) active sites.In contrast,pyrolyzing FePc alone forms Fe‐based nanoparticles embedded in amorphous carbon with only 5.9%Fe^(Ⅱ)‐N_(4) active sites.Both experimental characterization and density functional theory calculations reveal that spatial confinement through the staggeredπ–πstacking of Pc macrocycles effectively prevents the demetallation of Fe atoms and the formation of Fe‐based nanoparticles via aggregation.Furthermore,Zn‐induced microporous defects allow the fixation of Fe^(Ⅱ)‐N_(4) active sites.The synergistic effect of staggered stacking confinement and microporous defect fixation results in a high density of atomic Fe^(Ⅱ)‐N_(4) active sites that can enhance the ORR.The optimal Fe^(Ⅱ)‐N_(4)‐C electro‐catalyst outperforms a commercial Pt/C catalyst in terms of half‐wave potential,methanol toler‐ance,and long‐term stability in alkaline media.This modulation strategy can greatly advance efforts to develop high‐performance NPMCs.

Changes in the Physico-Chemical Properties of Human Kidney Cell Membranes during the Cancer Transformation

Kidney tissue is particularly susceptible to reactive oxygen species attack which leads to development of cancer. During oxidative stress, membrane lipids and proteins are major targets of re-active oxygen species (ROS). This work is focused on changes of phospholipids, proteins content and electric charge that occur in cell membranes of kidney cancer of pT3 stage, grade G3 and with metastasis. Qualitative and quantitative phospholipid composition and the presence of integral membrane proteins were determined by high-performance liquid chromatography. Electrophoresis was used to determine the surface charge density of the human kidney cell membrane. It was shown that the process of cancer transformation was accompanied by an increase phospholipid levels and altered the level of integral proteins as determined by decrease phenylalanine, tyrosine, cysteine and arginine. Moreover, the process of cancer transformation significantly enhanced changes in the surface charge density of the human kidney cell membrane. Cell membrane structure and function are modified by neoplasm lesion.

High index surface‐exposed and composition‐graded PtCu_(3)@Pt_(3)Cu@Pt nanodendrites for high‐performance oxygen reduction

Alloying and nanostructuring are two strategies used to facilitate the efficient electrocatalysis of the oxygen reduction reaction(ORR)by Pt,where the high index surfaces(HISs)of Pt exhibit superior activity for ORR.Here,we report the fabrication of PtCu3 nanodendrites possessing rich spiny branches exposing n(111)×(110)HISs.The dendrites were formed through an etching‐modulated seeding and growing strategy.Specifically,an oxidative atmosphere was initially applied to form the concaved nanocubes of the Pt‐Cu seeds,which was then switched to an inert atmosphere to promote an explosive growth of dendrites.Separately,the oxidative or inert atmosphere failed to produce this hyperbranched structure.Electrochemical dealloying of the PtCu3 nanodendrites produced Pt3Cu shells with Pt‐rich surfaces where HIS‐exposed dendrite structures were maintained.The resulting PtCu_(3)@Pt_(3)Cu@Pt nanodendrites in 0.1 M HClO4 exhibited excellent mass and area specific activities for ORR,which were 14 and 24 times higher than that of commercial Pt/C,respectively.DFT calculations revealed that Cu alloying and HISs both contributed to the significantly enhanced activity of Pt,and that the oxygen binding energy on the step sites of HISs on the PtCu_(3)@Pt_(3)Cu@Pt nanodendrites approached the optimal value to achieve a near peak‐top ORR activity.

Ni(OH)_2-Ni/C for hydrogen oxidation reaction in alkaline media

The development of the hydrogen electrode is vital for the application of alkaline polymer electrolyte fuel cells(APEFCs).In this study,a series of Ni(OH)_2 decorated Ni/C catalysts(Ni(OH)_2-Ni/C) were prepared by a three-step electrochemical treatment of Ni/C.The existence of Ni(OH)_2 was demonstrated by X-ray photoelectron spectroscopy(XPS),and the surface molar ratio of Ni(OH)_2/Ni of the samples was estimated via an electrochemical method.The HOR catalytic activity of the catalysts was evaluated by a rotation disk electrode(RDE) method,and a "volcano plot" was established between the HOR exchange current(j0) and the surface molar ratio of Ni(OH)_2/Ni.On top of the "volcano",the surface molar ratio of Ni(OH)_2/Ni is1.1:1,the j0 of which was 6.8 times of that of Ni/C.The stability of the samples toward HOR was evaluated to be good.Our study added a systematic experimental evidence to the HOR research,showing that the HOR catalytic activity of Ni can be deliberately controlled via decoration of Ni(OH)_2,which may help understanding the HOR mechanism on Ni.

Guided lithium nucleation and growth on lithiophilic tin-decorated copper substrate

Lithium metal is the ultimate anode choice for high energy rechargeable lithium batteries owing to its ultra-high theoretical capacity,however,Li dendrites and low Coulombic efficiency(CE)caused by disordered Li plating restrict its practical application.Herein,we develop an ultrathin Sn-decorated Cu substrate(Sn@Cu)fabricated by an electroless plating method to induce ordered Li nucleation and growth behavior.The lithiophilic Sn interfacial layer is found to play a critical role to lower the Li nucleation over-potential and promote fast Li-migration kinetics,and the underlying mechanism is revealed using the first principle calculations.Accordingly,a dense dendrite-free and Li deposition with large granular morphology is obtained,which significantly improved the CE and cycling performance of Li‖Sn@Cu half cells symmetric cells.Symmetric cells using the Li-Sn@Cu electrode display a much-prolonged life span(>1200 h)with low overpotential(~18 mV)at a high current density of 1 mA cm^(-2).Moreover,full cells paired with commercial LiFePO_(4) cathode(1.8 mAh cm^(-2))deliver enhanced cycling stability(0.5 C,300 cycles)and excellent rate performance.This work provides a simple and effective way to bring about high efficiency and long lifespan substrates for practical applications.

Electrocatalytic volcano relations:surface occupation effects and rational kinetic models

Electrocatalysis plays a vital role in technologies of energy and environment relevance,such as water electrolysis,fuel cells,synthesis of carbon and nitrogen-based fuels,etc.The volcano relations(VRs)are general and standard tools for predicting and understanding the activity trends of electrocatalysts.The modern electrocatalytic VRs are generally based on the kinetic models with the maximum free energy(△G^(0)_(max))of reaction steps as the rate-determining term(RDT),in which some important factors that crucially impact the reaction kinetics are missed,for examples,the surface structures and coverages of reaction intermediates and spectators,other free energy demanding steps than that associated with the △G^(0)_(max),and so on.In this perspective,we first give a brief introduction of the theoretical framework of current electrocatalytic VRs and the underlying problems in the oversimplifiedDG0max-based kinetic models,and then provide an account of our effort in constructing more rational VRs for electrocatalytic reactions.We introduce a new theoretical framework of electrocatalytic VRs based on kinetic model with the so-called energetic span(δE)serving as RDT.Since the surface-coverage effects and multiple free energy-demanding steps are considered,the VRs thus obtained show several new features such as strong potential dependence,asymmetric ascending and descending branches,relatively flat tops,and so on.The effectiveness of theδE-based VRs is verified for hydrogen and oxygen electrocatalytic reactions.Finally,research directions to further rationalize the electrocatalytic VRs are discussed.

Guanine-regulated proton transfer enhances CO_(2)-to-CH_(4) selectivity over copper electrode

Electrocatalytic CO_(2) reduction has attracted growing attention as a promising route to realize artificial carbon recycling.Proton transfer plays an essential role in CO_(2) reduction and dramatically impacts product distribution.However,the precise control of proton transfer during CO_(2) reduction remains challenging.In this study,we present a well-controlled proton transfer through the modification of several purines with similar molecular structures,and reveal a direct correlation between surface proton transfer capability and CO_(2) reduction selectivity over Cu electrode.With a moderate proton transfer capability,the guanine modification can remarkably boost CH_(4) production and suppress C2 products formation.In-situ ATR-SEIRAS suggests a weakened^(*)CO intermediate adsorption and a relatively low local pH environment after the guanine modification,which facilitates the^(*)CO protonation and detachment for CH_(4) generation.

Li Plating on Carbon Electrode Surface Probed by Low-Field Dynamic Nuclear Polarization ^(7)Li NMR

Lithium deposition on graphite electrode not only reduces fast-charging capability of lithium ion batteries but also causes safety trouble.Here,a low-field^(7)Li dynamic nuclear polarization(DNP)is used to probe Li plating on the surfaces of three types of carbon electrodes:hard carbon,soft carbon and graphite.Owing to the strong Fermi contact interaction between^(7)Li and conduction electrons,the^(7)Li nuclear-magnetic-resonance(NMR)signal of Li metal deposited on electrode surface could be selectively enhanced by DNP.It is suggested that low-field^(7)Li DNP spectroscopy is a sensitive tool for investigating Li deposition on electrodes during charging/discharging processes.

Photocatalytic nonoxidative coupling of methane to ethylene over carbon-doped ZnO/Au catalysts

A photocatalytic nonoxidative coupling of methane to multi-carbon compounds remains a huge challenge due to its high dissociation energy of C–H bonds and sluggish charge carrier dynamics.Au-modified carbon-doped ZnO(C-ZnO/Au)photocatalyst is constructed by an interfacial modification-assisted self-assembly approach for efficient photocatalytic nonoxidative coupling of methane to ethylene and hydrogen(2CH_4=C_2H_4+2H_2).Benefitting from the presence of C-ZnO/Au interfaces,the catalyst not only weakens the excitonic confinement to improve the photogenerated charge carrier separation,but also enhances the stability of lattice oxygen to suppress C_2H_4 overoxidation.Moreover,this hybrid catalyst also accelerates the generation of Zn~+–O~–pairs to activate C–H bonds,stabilizes the important reaction intermediate(*OCH_3)to achieve the C–C coupling,and promotes the generation of low-valence Zn to accelerate the dehydrogenation of the*OC_2H_5 into C_2H_4.Therefore,a stable photocatalytic methane conversion performance can be achieved over C-ZnO/Au heterojunctions with a stoichiometric generation of the oxidation product(C_2H_4,45.85μmol g~(-1)h~(-1))and reduction product(H_2,88.07μmol g~(-1)h~(-1)).This work provides deep insights into the elemental doping and oxide/Au interfaces for the enhanced photocatalytic activity and product selectivity under mild conditions in the absence of extra oxidants.

Modulation of Excitonic Confinement of TiO_(2)in Molten Salts for Overall CO_(2)Photoreduction

Excitonic confinement greatly determines the charge carrier transport of photocatalysts.A molten salt modulation of excitonic con-finement is herein demonstrated as formation of ultrafine carbon-doped anatase TiO_(2)with grafted graphitic carbon nitride,which is rationalized as an excellent catalyst for overall CO_(2)photoreduction.Compared with bulk TiO_(2),the carbon-doped TiO_(2)(M-TiO_(2))pos-sesses a weaker excitonic confinement to decrease exciton binding energy from 99 to 58 meV,consequently enhancing free-charge-carrier generation and transportation.Effective Z-scheme electron transfer from M-TiO_(2)to C_(3)N_(4) is built,enhancing the CO_(2)conversion via the synchronous optimization of redox ability,CO_(2)activation,and^(*)COOH generation.This work highlights the unique chemistry of excitonic dissociation on facilitating separation of electron and hole,and also extends the scope of molten salt-mediated modulation of photocatalysis materials.