Bimetallic In_(2)O_(3)/Bi_(2)O_(3) Catalysts Enable Highly Selective CO_(2) Electroreduction to Formate within Ultra-Broad Potential Windows

CO_(2)electrochemical reduction reaction(CO_(2)RR)to formate is a hopeful pathway for reducing CO_(2)and producing high-value chemicals,which needs highly selective catalysts with ultra-broad potential windows to meet the industrial demands.Herein,the nanorod-like bimetallic ln_(2)O_(3)/Bi_(2)O_(3)catalysts were successfully synthesized by pyrolysis of bimetallic InBi-MOF precursors.The abundant oxygen vacancies generated from the lattice mismatch of Bi_(2)O_(3)and ln_(2)O_(3)reduced the activation energy of CO_(2)to*CO_(2)·^(-)and improved the selectivity of*CO_(2)·^(-)to formate simultaneously.Meanwhile,the carbon skeleton derived from the pyrolysis of organic framework of InBi-MOF provided a conductive network to accelerate the electrons transmission.The catalyst exhibited an ultra-broad applied potential window of 1200 mV(from-0.4 to-1.6 V vs RHE),relativistic high Faradaic efficiency of formate(99.92%)and satisfactory stability after 30 h.The in situ FT-IR experiment and DFT calculation verified that the abundant oxygen vacancies on the surface of catalysts can easily absorb CO_(2)molecules,and oxygen vacancy path is dominant pathway.This work provides a convenient method to construct high-performance bimetallic catalysts for the industrial application of CO_(2)RR.

Cu/CdcO_(3)catalysts for efficient electrochemical CO_(2)reduction over the wide potential window

High efficiency and low-cost catalyst-driven electrocatalytic CO_(2)reduction to CO production are of great significance for energy storage and development.The severe competitive hydrogen evolution reaction occurs at large negative potential window limits the achievement of the target product from CO_(2)at high efficiency.Here,we successfully prepared Cu_(x)/CdcO_(3)composite catalyst rich in interfaces,in which achieved high CO Faraday eficiency exceeded 90%in a wide potential window of 700 mV and highest value up to 97.9%at-0.90V vs.RHE.The excellent performance can be ascribed to the positive contribution of Cu_(x)/CdcO_(3),which maintains a suitable high local pH value during electrochemical reduction,thus inhibiting the competitive hydrogen evolution reaction.Moreover,the compact structure between Cu and CdCO_(3)ensures fast electron transfer both inside catalysts and interface,thus speeding up the reaction kinetics of CO_(2)to CO conversion.Theoretically calculations further prove that the combination of Cu and CdcO_(3)provides the well-defined electronic structure for intermediates adsorption,significantly reducing the reaction barrier for the formation of co.This work provides new insights into the design of eficient electrochemical CO_(2)reduction catalysts for inhibiting hydrogen evolution by adjusting the local pH effect.

Electrochemical and structural performances of Li[Ni_(0.133)Li_(0.2)Co_(0.133)Mn_(0.533)]O_(2)material during different cycle potential windows

The effects of cycle potential window on electrochemical behaviors,structural characteristics,and surface changes in Li[Ni_(0.133)Li_(0.2)Co_(0.133)Mn_(0.533)]O_(2)(or 0.5 Li_(2)MnO_(3)·0.5 Li(Co_(0.333)Ni_(0.333)Mn_(0.333))O2)in lithium-ion battery were investigated.Two flat charge potential plateaus,~3.9 and~4.5 V,are observed in the initial charge curves of the cells.Sharp changes in specific capacity and columbic efficiency are presented at~4.5 V during the first cycle.XRD specific peaks show an obvious shift with the increase in charge cutoff potential.When the charge cutoff potential is above4.4 V,the cycle performance decreases with the increase in charge cutoff potentials.A film with the composition of C and O elements is observed on the cycled composite particle.

Sub-2 nm ultra-thin Bi_(2)O_(2)CO_(3)nanosheets with abundant Bi-O structures toward formic acid electrosynthesis over a wide potential window

The electrocatalytic reduction of CO_(2)to HCOOH(ERC-HCOOH)is one of the most feasible ways to alleviate energy crisis and solve environmental problems.Nevertheless,it remains a challenge for ERC-HCOOH to maintain excellent activity and selectivity in a wide potential window.Herein,ultra-thin flower-like Bi_(2)O_(2)CO_(3)nanosheets(NSs)with abundant Bi-O structures were in situ synthesized on carbon paper via topological transformation and post-processing.Faraday efficiency of HCOOH(FEHCOOH)reached 90%in a wide potential window(-1.5 to-1.8 V vs.Ag/AgCl).Significantly,excellent FEHCOOH(90%)and current density(47 mA·cm^(-2))were achieved at-1.8 V vs.Ag/AgCl.The X-ray absorption fine structure(XAFS)combined with density functional theory(DFT)calculation demonstrated that the excellent performance of Bi_(2)O_(2)CO_(3)NS was attributed to the abundant Bi-O structures,which was conducive to enhancing the adsorption of CO_(2)^(*)and OCHO^(*)intermediates and can effectively inhibit hydrogen evolution.The excellent performance of Bi_(2)O_(2)CO_(3)NS over a wide potential window could provide new insights for the efficient electrocatalytic conversion of CO_(2).

Redox-etching induced porous carbon cloth with pseudocapacitive oxygenic groups for flexible symmetric supercapacitor

Constructing high-performance electrodes with both wide potential window(e.g.≥2 V in aqueous electrolyte)and excellent mechanical flexibility represents a great challenge for supercapacitors.Because of the outstanding conductivity and flexibility,carb on cloth(CC)has show n unlimited prospects for constructing flexible electrodes,but is rarely used directly as electrode material due to its electrochemical inertness and small specific surface area.To tackle these two critical limitations,we design a novel redox-etching strategy to synthesize CC-based electrode with 3D interconnecting pore structure.The sponge-like highly porous CC was further activated by strong oxidant to form abundant oxygenic groups,which occupy the interior and surface of current collector to render substantial pseudocapacitance.The as-synthesized CC electrode yielded an impressive capacitance of 4035 mF cm^(-2) at 3 mA cm^(-2) and satisfying cycling durability in a wide potential range of-1-1 V vs.SCE,which surpass the majority of reported CC-based electrodes.A symmetric supercapacitor with stable voltage of 2 V is assembled and delivers remarkable energy density of 6.57 mWh cm^(-3).Significantly,the device demonstrates an unparalleled flexibility with no capacitive decay after 100 bending cycles.This facile chemical etching and post-treatment processes are designed for large-scale manufacturing of the CC electrodes by providing high surface area and abundant electrochemically active sites,promising for industry application.The innovative synthetic strategy ope ns up new opportunities for high-performance flexible en ergy storage.

Electrolyte effect on electrochemical behaviors of manganese fluoride material for aqueous asymmetric and symmetric supercapacitors

Exploring wide voltage window materials is not only an available measure to enhance the energy density of hybrid supercapacitor(HSCs),but also avoids the dynamic mismatch caused by different energy storage mechanisms of two electrodes in assembled symmetrical HSC.However,there are few reports about the wide potential window materials except Bi_(2)O_(3)and VO_(2).Therefore,the MnF_(2)synthesized by solvothermal reaction was served as the electrode for HSC.The MnF_(2)exhibited electrochemical activity in alkaline solution in three-electrode system,especially with a wide potential window from-0.8 to+0.5 V in 2 mol·L^(-1)NaOH.Furthermore,the assembled MnF_(2)//MnF_(2)symmetrical HSC had a potential window of 1.5 V,and it exhibited outstanding long-cycle capability.Meanwhile,when MnF_(2)was taken as the negative and positive respectively,the potential windows of asymmetric devices CoMoO_(4)//MnF_(2)and MnF_(2)//Activated Carbon(AC)could reach 1.3 and 1.45 V,respectively,showing excellent cycle stability.This work shows that MnF_(2)material has great research value in HSC,and provides a new research direction for developing high-performance devices.

The electrochemical stability of ionic liquids and deep eutectic solvents

Room temperature ionic liquids （ILs） composed of cations and anions, as well as deep eutectic solvents （DESs） composed of hydrogen bond donors （HBDs） and hydrogen bond acceptors （HBAs）, are regarded as green solvents due to their low volatility. They have been used widely for electrochemically driven reactions because they exhibit high conductivity and excellent elec- trochemical stability. However, no systematic investigations on the electrochemical potential windows （EPWs）, which could be used to characterize the electrochemical stability, have been reported. In this regard, the EPWs of 33 ILs and 23 DESs have been studied utilizing cyclic voltammetry （CV） method and the effects of structural factors （cations and anions of ILs, and HBDs and HBAs of DESs） and external factors （electrode, water content） on the EPWs have been comprehensively investi- gated. The electrochemical stability of selected 1Ls comprising five traditional cations, namely imidazolium, pyridinium, pyr- rolidinium, piperidinium and ammonium and 13 kinds of versatile anions was studied. The results show that for ILs, both cati- on and anion play an important role on the reductive and oxidative potential limit. For a same IL at different working electrode, for example, glassy carbon （GC）, gold （Au） and platinum （Pt） electrode, the largest potential window is almost observed on the GC working electrode. The investigations on the EPWs of choline chloride （ChCl）, choline bromide （ChBr）, choline iodide （ChI）, and methyl urea based DESs show that the DES composed of ChCl and methyl urea has the largest potential window. This work may aid the selection of ILs or DESs for use as a direct electrolyte or a solvent in electrochemical applications.

Fabrication of high Li:water molar ratio electrolytes for lithium-ion batteries

Hydrous electrolytes with high electrochemical potentials were obtained by hydrating water molecules into solutes to form high Li:water molar ratio electrolytes(HMRE).Solid polyethylene glycol(PEG) were e mployed to enha nce the molar ratio of Li^(+) to water in the electrolytes while reducing the consumption of Li-salt.The obtained mole ratio of Li^(+) to wa ter molecules in the hydrous electrolytes was greater than 1:1;however,the mass fraction of Li-salt was reduced to 61%(approximately 5.5 mol/kg,based on water and PEG).Compared with that of water-in-salt electrolytes,the mass fraction of Li-salt could be remarkably reduced by adding solid PEG.The electrochemical stability of the electrolytes improved considerably because of the strong hydration of Li^(+) by the water molecules.A beneficial passivation effect,arising from the decomposition of the electrolyte,at a wide potential window was observed.

Preparation of safe water-lipid mixed electrolytes for application in ion capacitor

Aqueous electrolytes are safe,economic,and environmentally friendly.However,they have a narrow potential window.On the other hand,organic electrolytes exhibit good thermodynamic stability but are inflammable and moisture sensitive.In this study,we prepared water-PEG-lipid ternary electrolytes(TEs).To combine the advantages of water,polyethylene glycol(PEG)and propylene carbonate(PC).The nonflammable mixed electrolytes exhibited a wide potential window of about 2.8 V due to the beneficial effects of PEG and PC.Using these TEs,a lithium manganate-active carbon ion capacitor could be operated at 2.4 V with an energy density of 32 Wh/kg,based on the total active electrode material(current density of 3.3 m A/cm^(2)).This value was significantly higher than that achieved using an aqueous electrolyte,thereby rationalizing the higher energy density.