Trace Cobalt Doping and Defect Engineering of High Surface Area α-Ni(OH)_(2) for Electrocatalytic Urea Oxidation

Owing to the intrinsically sluggish kinetics of urea oxidation reaction(UOR)involving a six-electron transfer process,developing efficient UOR electrocatalyst is a great challenge remained to be overwhelmed.Herein,by taking advantage of 2-Methylimidazole,of which is a kind of alkali in water and owns strong coordination ability to Co^(2+)in methanol,trace Co(1.0 mol%)addition was found to induce defect engineering onα-Ni(OH)_(2)in a dual-solvent system of water and methanol.Physical characterization results revealed that the synthesized electrocatalyst(WM-Ni_(0.99)Co_(0.01)(OH)_(2))was a kind of defective nanosheet with thickness around 5-6 nm,attributing to the synergistic effect of Co doping and defect engineering,its electron structure was finely altered,and its specific surface a rea was tremendously enlarged from 68 to 172.3 m^(2)g^(-1).With all these merits,its overpotential to drive 10 mA cm^(-2)was reduced by 110 mV.Besides,the interfacial behavior of UOR was also well deciphered by operando electrochemical impedance spectroscopy.

High-Performance and Large-Area Inverted Perovskite Solar Cells Based on NiO_(x) Films Enabled with A Novel Microstructure-Control Technology

The improvement in the efficiency of inverted perovskite solar cells(PSCs)is significantly limited by undesirable contact at the NiO_(x)/perovskite interface.In this study,a novel microstructure-control technology is proposed for fabrication of porous NiO_(x)films using Pluronic P123 as the structure-directing agent and acetylacetone(AcAc)as the coordination agent.The synthesized porous NiO_(x)films enhanced the hole extraction efficiency and reduced recombination defects at the NiO_(x)/perovskite interface.Consequently,without any modification,the power conversion efficiency(PCE)of the PSC with MAPbl_(3)as the absorber layer improved from 16.50%to 19.08%.Moreover,the PCE of the device composed of perovskite Cs0.05(MA_(0.15)FA_(0.85))_(0.95)Pb(I_(0.85)Br_(0.15))_(3)improved from 17.49%to 21.42%.Furthermore,the application of the fabricated porous NiO_(x)on fluorine-doped tin oxide(FTO)substrates enabled the fabrication of large-area PSCs(1.2 cm^(2))with a PCE of 19.63%.This study provides a novel strategy for improving the contact at the NiO_(x)/perovskite interface for the fabrication of high-performance large-area perovskite solar cells.

Highly selective electrosynthesis of imines via electroreduction coupling of nitroarenes with aryl aldehydes on Co_(9)S_(8)with positively charged sulfur vacancies

The electrocatalytic synthesis of imines through the reductive imination of nitroarenes with aldehydes is a facile,environmentally friendly,and valuable process.In this study,high selectivity electrosynthesis of imines was realized through the electrocatalytic C-N coupling reaction between nitroarenes and aryl aldehydes on Co_(9)S_(8)nanoflowers with rich sulfur vacancies(Co_(9)S_(8)-Vs).Comparative experiments revealed that positively charged sulfur vacancies play a pivotal role in boosting catalytic selectivity towards imines.Electron-deficient sulfur vacancies intensified the adsorption of negatively charged Ph-NO_(2),thereby enhancing the conversion rate of the electrochemical nitrobenzene-reduction reaction(eNB-RR).Simultaneously,sulfur vacancies augmented the adsorption capability of negatively charged Ph-CHO,enriching Ph-CHO species at the electrode interface and expediting the Schiff base condensation reaction rate.The experimental results show that the reaction conditions can satisfy the different nitroarenes and aryl aldehydes in the electrocatalytic aqueous-phase system under mild conditions to obtain the corresponding imine products in high selectivity.This study provides a facile and environmentally friendly pathway for future electrocatalytic synthesis of imine.

新工科背景下湖南大学应用化学专业的改革与建设

探索建立依托化学学科的"新工科"应用化学专业设置并按照"新工科"理念对现有专业进行革命性改造是十分必要的。结合我校2020应用化学专业培养计划修订及教学改革研究的实际情况,通过调整专业培养目标、课程体系、教学内容和教学模式,突出德才兼备人才培养的中心地位,以期在传承本专业腐蚀与防护的特色基础上,进一步满足新材料、新能源、高端制造、节能环保及新一代信息技术等新兴战略产业对人才的需求。还提出了应用化学新工科专业发展的方向。

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.

Transforming Co3O4 nanosheets into porous N-doped CoxOy nanosheets with oxygen vacancies for the oxygen evolution reaction

Cobalt oxides have been widely investigated as promising replacements for noble metal-based catalysts for oxygen evolution reaction(OER). Herein, we, for the first time, have obtained porous CoxOy nanosheets with N-doping and oxygen vacancies by etching Co3O4 nanosheets with NH3 plasma. Comparing with the pristine Co3O4 nanosheets(1.79 V), the porous CoxOy nanosheets with N-doping and oxygen vacancies have a much lower potential of 1.51 V versus RHE to reach the current density of 10 mA cm-2. The obtained sample has a lower Tafel slope of 68 m V dec-1 than the pristine Co3O4 nanosheets(234 mV dec-1).The disclosed Co^2+, which is responsible for the formation of active sites(CoOOH), N-doping and oxygen vacancies, gives rise to better performance of OER.

Sulfonic groups functionalized Zr-metal organic framework for highly catalytic transfer hydrogenation of furfural to furfuryl alcohol

The highly selective catalytic transfer hydrogenation(CTH)of furfural(FF)to furfuryl alcohol(FOL)is a significant route of biomass valorization.Herein,a series microporous Zr-metal organic framework(ZrMOF)functionalized by sulfonic groups are prepared.Based on the comprehensive structural characterizations by means of X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),N2 physisorption,Thermogravimetric(TG)and Fourier transformed infrared spectroscopy(FTIR),we find that sulfonic acid(–SO_(3)H)functional groups are tethered on the UIO-66 without affecting the structure of the framework.Systematic characterizations(NH_(3)-TPD,CO_(2)-TPD,and in-situ FTIR)demonstrate that modifying of sulfonic groups on UIO-66 results in the formation of stronger Lewis acidic-basic and Brnsted acidis sites.The cooperative role of the versatile Lewis acidic-basic and Brnsted acidic sites in 60%mol fraction of sulfonic acid-containing UIO-66(UIO-S_(0.6))retain high surface area and exhibit excellent catalytic performance of 94.7%FOL yield and 16.9 h^(-1).turnover number(TOF)under mild conditions.Kinetic experiments reveal that the activation energy of the CTH of furfural(FF)over UIO-S_(0.6) catalyst is as low as 50.8 k J mol^(-1).Besides,the hydrogen transfer mechanism is investigated through isotope labeling experiments,exhibiting that theβ-H in isopropanol is transferred to the a-C of FF by forming six-membered intermediates on the Lewis acidic-basic and Brnsted acidic sites of the UIO-S_(0.6),which is the rate-determining step in the formation of FOL.

Ultrathin defective high-entropy layered double hydroxides for electrochemical water oxidation

One of the fundamental driving forces in the materials science community is the hunt for new materials with specific properties that meet the requirements of rapidly evolving technology.

Recent Progress on Electrocatalytic Valorization of Biomass-Derived Organics

Electrocatalytic valorization of biomass derivatives can be powered by electricity generated from renewable sources such as solar and wind energy.A shift from centralized,high-temperature,and energy-intensive processes to decentralized,low-temperature conversions is achieved,which meets the requirement of sustainable energy generation.This approach provides an efficient,green,and additive-free strategy for biomass derivative valorization,in which product selectivity could be easily regulated by the applied potential and electrocatalyst utilized.However,a scale-up application is still far from being completed due to the inability of conversion rates and selectivity to meet the industrialization requirements.A better understanding of the reaction mechanism and the development of highefficiency and high-selectivity electrocatalysts are required to pave the path toward larger industrialization applications.Herein,we summarize the recent research progress in the electrocatalytic oxidation and hydrogenation of platform compounds such as furanic compounds and glycerol.In the literature,these three research areas are integrated to realize the scale-up application of the processes as mentioned above.The investigations of the mechanism are based on in situ techniques,theoretical calculations,and advanced electrocatalyst studies.Finally,the challenges and prospects in this topic are described.We expect that this review will provide the fundamental understanding and design guidelines to achieve efficient and high-selectivity catalysts and further facilitate the scale-up application of the electrocatalytic conversion of biomass derivatives.

Activity origin and alkalinity effect of electrocatalytic biomass oxidation on nickel nitride

Electro-oxidation of 5-hydroxymethylfurfural(HMFOR)is a promising green approach to realize the conversion of biomass into value-added chemicals.However,considering the complexity of the molecular structure of HMF,an in-depth understanding of the electrocatalytic behavior of HMFOR has rarely been investigated.Herein,the electrocatalytic mechanism of HMFOR on nickel nitride(Ni3 N)is elucidated by operando X-ray absorption spectroscopy(XAS),in situ Raman,quasi in situ X-ray photoelectron spectroscopy(XPS),and operando electrochemical impedance spectroscopy(EIS),respectively.The activity origin is proved to be Ni^(2+δ)N(OH)ads generated by the adsorbed hydroxyl group.Moreover,HMFOR on Ni3 N relates to a two-step reaction:Initially,the applied potential drives Ni atoms to lose electrons and adsorb OH-after 1.35 VRHE,giving rise to Ni^(2+δ)N(OH)ads with the electrophilic oxygen;then Ni^(2+δ)N(OH)ads seizes protons and electrons from HMF and leaves as H_(2) O spontaneously.Furthermore,the high electrolyte alkalinity favors the HMFOR process due to the increased active species(Ni^(2+δ)N(OH)ads)and the enhanced adsorption of HMF on the Ni3 N surface.This work could provide an in-depth understanding of the electrocatalytic mechanism of HMFOR on Ni3 N and demonstrate the alkalinity effect of the electrolyte on the electrocatalytic performance of HMFOR.

pH-Induced selective electrocatalytic hydrogenation of furfural on Cu electrodes

The efficient and selective electrocatalytic hydrogenation(ECH)of furfural is considered a green strategy for achieving biomass-derived high-value chemicals.Regulating an aqueous electrolytic environment,a green hydrogen energy source of water,is significant for improving the selectivity of products and reducing energy consumption.In this study,we systematically investigated the mechanism of pH dependence of product selectivity in the ECH of furfural on Cu electrodes.Under acidic conditions,the oxygen atom dissociated directly from hydrogenated furfural-derived alkoxyl intermediates,followed by stepwise hydrogenation until H_(2)O formation via a thermodynamically favorable proton-coupled electron transfer process,thereby inducing a high proportion of the hydrogenolysis product(2-methylfuran).However,under partial alkaline conditions,furfural could be directly hydrogenated to furfuryl alcohol(selectivity~98%)due to the high-energy barrier of the deoxidation process via a surface hydride(Had)transfer.Our results highlight the vital role of the electrolytic environment in furfural selective conversion and broaden our fundamental understanding of hydrodeoxygenation reactions in ECH.

Understanding the surface segregation behavior of bimetallic CoCu toward HMF oxidation reaction

Surface segregation is ubiquitous in multi-component materials and is of great important for catalysis but little is known on the surface structure under graphene encapsulation.Here,we show that the graphene encapsulated CoCu performs well for the electrocatalytic oxidation of 5-hydroxymethylfurfural(HMF)to2,5-furandicarboxylic acid(FDCA)with the onset potential before 1.23 VRHEand a nearly 100%selectivity of FDCA under 1.4 VRHE.From the experimental results,the unprecedented catalytic performance was attributed to local structural distortion and sub-nanometer lattice composition of the CoCu surface.We accurately show the dispersed Cu doped Co_(3)O_(4) nano-islands with a lot of edge sites on the bimetallic Co-Cu surface.While,the gradient components effectively facilitate the establishment of built-in electric field and accelerate the charge transfer.Theoretical and experimental results reveal that the surface Co and neighbouring Cu atoms in sub-nanometer lattice synergistically promote the catalysis of HMF.This work offers new insights into surface segregation in tuning the element spatial distribution for catalysis.

A Pair-Electrosynthesis for Formate at Ultra-Low Voltage Via Coupling of CO_(2) Reduction and Formaldehyde Oxidation

Formate can be synthesized electrochemically by CO_(2) reduction reaction(CO_(2)RR)or formalde-hyde oxidation reaction(FOR).The CO_(2)RR approach suffers from kinetic-sluggish oxygen evolution reac-tion at the anode.To this end,an electrochemical sys-tem combining cathodic CO_(2)RR with anodic FOR was developed,which enables the formate electrosynthesis at ultra-low voltage.Cathodic CO_(2)RR employing the BiOCl electrode in H-cell exhibited formate Faradaic efficiency(FE)higher than 90% within a wide potential range from−0.48 to−1.32 V_(RHE).In flow cell,the current density of 100 mA cm^(−2) was achieved at−0.67 V_(RHE).The anodic FOR using the Cu_(2)O electrode displayed a low onset potential of−0.13 V_(RHE) and nearly 100%formate and H_(2) selectivity from 0.05 to 0.35 V_(RHE).The CO_(2)RR and FOR were constructed in a flow cell through membrane electrode assembly for the electrosynthesis of formate,where the CO_(2)RR//FOR delivered an enhanced current density of 100 mA cm^(−2) at 0.86 V.This work provides a promising pair-electrosynthesis of value-added chemicals with high FE and low energy consumption.

Regulating carbon work function to boost electrocatalytic activity for the oxygen reduction reaction

Electronic regulation of carbon is essential for developing non-platinum electrocatalysts for oxygen reduction reactions(ORRs).In this work,we used Cs to further regulate the electronic structure of nitrogen-doped(N-doped)carbon.The Cs atoms coordinated with the nitrogen atom in the N-doped carbon for injecting electrons into the carbon conjugate structure and reducing the work function of the carbon network.The low-work-function surface improved electron donation,facilitated O_(2) dissociation,and enhanced the adsorption of an OOH^(*) intermediate.Thus,electrocatalytic performance for the ORR was improved.The material shows potential as an ORR electrocatalyst comparable with Pt/C.

Anodic Electrosynthesis of Amide from Alcohol and Ammonia

Amide is essential in biologically active compounds,synthetic materials,and building blocks.However,conventional amide production relies on energyintensive consumption and activating agents that modulate processes to construct the C–N bond.Herein,for the first time,we have successfully realized the formation of amides at industrial current density via the anodic coelectrolysis of alcohol and ammonia under ambient conditions.We have proved thatmodulation of the interface microenvironment concentration of nucleophile by electrolyte engineering can regulate the reaction pathways of amides rather than acetic acids.The C-N coupling strategy can be further extended to the electrosynthesis of the long-chain and aryl-ring amide with high selectivity by replacing ammonia with amine.Our work opens up a vast store of information on the utilization of biomass alcohol for high-value N-containing chemicals via an electrocatalytic C-N coupling reaction.

Defect engineered electrocatalysts for C-N coupling reactions toward urea synthesis

Urea is extensively used in agriculture and chemical industry,and it is produced on an industrial scale from CO_(2)and Haber-Bosch NH_(3)under relatively high temperature and high pressure conditions,which demands high energy input and generates masses of carbon footprint.The conversion of CO_(2)and N sources(such as NO_(2)^(−),NO_(3)^(−),and N_(2))through electrocatalytic reactions under ambient conditions is a promising alternative to realize efficient urea synthesis.Of note,the design of electrocatalyst is one of the key factors that can improve the efficiency and selectivity of C-N coupling reactions.Defect engineer-ing is an intriguing strategy for regulating the electronic structure and charge density of electrocatalysts,which endows electrocatalysts with excellent physicochemical properties and optimized adsorption en-ergy of the reaction intermediates to reduce the kinetic barriers.In this minireview,recent advances of defect engineered electrocatalysts in urea electrosynthesis from CO_(2)and various N reactants are firstly introduced.Mechanistic discussions of C-N coupling in these advances are presented,with the aim of directing future investigations on improving the urea yield.Finally,the prospects and challenges of de-fect engineered electrocatalysts for urea synthesis are discussed.This overview is expected to provide in-depth understanding of structure-reactivity relationship and shed light on future electrocatalytic C-N coupling reactions.

Pulsed electrochemistry:A pathway to enhanced electrocatalysis and sustainable electrosynthesis

This review delves into pulsed electrochemistry,a new technique that is becoming an essential tool in the field of electrocatalysis and electrosynthesis.Unlike traditional potentiostatic methods,pulsed electrochemical approaches provide dynamic control over catalytic reactions,leading to better selectivity,efficiency,and stability across a range of applications.We examine the underlying theory of pulsed electrocatalysis and explore how waveform characteristics,potential,and pulse time affect catalytic processes.The review pays special attention to its application in key areas such as organic electrosynthesis,CO_(2) reduction reactions,and water splitting,explaining how pulsed techniques improve reaction conditions to boost yields and selectivity.Meanwhile,we focus on the technique’s impact on catalyst surface modulation,managing local interface environments,and addressing issues like catalyst deactivation and mass transfer limitations.Ultimately,this review highlights the transformative potential of pulsed electrochemistry in driving various electrocatalysis and electrosynthesis applications and sets the stage for future exploration and optimization of these electrochemistry systems.

Rational design of three-phase interfaces for electrocatalysis

Gas-involving electrochemical reactions,like oxygen reduction reaction (ORR),oxygen evolution reaction (OER),and hydrogen evolution reaction (HER),are critical processes for energy-saving,environment-friendly energy conversion and storage technologies which gain increasing attention.The development of according electrocatalysts is key to boost their electrocatalytic performances.Dramatic efforts have been put into the development of advanced electrocatalysts to overcome sluggish kinetics.On the other hand,the electrode interfaces-architecture construction plays an equally important role for practical applications because these imperative electrode reactions generally proceed at triple-phase interfaces of gas,liquid electrolyte,and solid electrocatalyst.A desirable architecture should facilitate the complicate reactions occur at the triple-phase interfaces,which including mass diffusion,surface reaction and electron transfer.In this review,we will summarize some design principles and synthetic strategies for optimizing triple-phase interfaces of gas-involving electrocatalysis systematically,based on the electrode reaction process at the three-phase interfaces.It can be divided into three main optimization directions:exposure of active sites,promotion of mass diffusion and acceleration of electron transfer.Furthermore,we especially highlight several remarkable works with comprehensive optimization about specific energy conversion devices,including metal-air batteries,fuel cells,and water-splitting devices are demonstrated with superb efficiency.In the last section,the perspectives and challenges in the future are proposed.

Single-crystalline layered double hydroxides with rich defects and hierarchical structure by mild reduction for enhancing the oxygen evolution reaction

The oxygen evolution reaction(OER)with sluggish reaction kinetics and large overpotential is the critical reaction in water splitting that is promising for energy storage and conversion.Layered double hydroxides(LDHs),due to their unique lamellar structure and flexibility of chemical component,are very competing material candidates for OER.Herein,the morphology structure and the electronic structure of LDHs were simultaneously tuned to improve the OER catalytic activity by mild solvothermal reduction using ethylene glycol.The increased surface area,the introduction of oxygen vacancies and the construction of hierarchical structure greatly enhanced the electro-catalytic activity of LDHs for OER.The as-prepared LDHs showed a lower over-potential as low as 276 mV at a current density of 10 mA cm-2,and a small Tafel slope of 40.3 mV dec-1 accompanied with good stability.This work provides an efficient way to the design and optimization of advanced catalysts in the future.

Low-temperature plasma technology for electrocatalysis

Electrochemical reactions were widely used in energy storage and conversion devices. The development of low-cost, highly efficient and stable electrocatalyst is essential to a large-scale application of energy storage and conversion devices. Recently, emerging plasma technology has been employed as one of the practical ways to synthesize and modify electrocatalysts due to its unique property. In this review, we summarized the latest applications of plasma in energy storage and conversion, including using it as the preparation and modification technology of the various electrocatalysts and the usage of it as the synthesis technology directly. Firstly, we presented the definition and types of plasma reactors and their respective characteristics. Then, these applications of plasma technology in many essential electrode reactions including carbon dioxide reduction reaction(CO_2RR), nitrogen fixation, oxygen reduction reaction(ORR), oxygen evolution reaction(OER) and hydrogen evolution reaction(HER) were introduced.Finally, the challenges and outlook of plasma technology in energy storage and conversion were summarized, and the solutions and prospected its development in the future were present. Through reviewing the related aspects, readers can have a deeper understanding of the application prospects of plasma in electrocatalysis.