Boosting overall water splitting by incorporating sulfur into NiFe(oxy)hydroxide

Developing highly active and cost-effective electrocatalysts for enhancing the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)is a significant challenge for overall water splitting.Sulfur-incorporated nickel iron(oxy)hydroxide(S-NiFeOOH)nanosheets were directly grown on commercial nickel foam using a galvanic corrosion method and a hydrothermal method.The incorporation of sulfur into NiFeOOH enhanced the catalytic activity for the HER and OER in 1 M KOH electrolyte.The enhanced catalytic activity is attributed to the change in the local structure and chemical states due to the incorporation of sulfur.High performance for overall water splitting was achieved with an alkaline water electrolyzer.This was realized by employing S-NiFeOOH as a bifunctional electrocatalyst,thereby outperforming a water electrolyzer that requires the usage of precious metal electrocatalysts(i.e.,Pt/C as the HER electrocatalyst and IrO_(2) as the OER electrocatalyst).Moreover,when driven by a commercial silicon solar cell,an alkaline water electrolyzer that uses S-NiFeOOH as a bifunctional electrocatalyst generated hydrogen under natural illumination.This study shows that S-NiFeOOH is a promising candidate for a large-scale industrial implementation of hydrogen production for overall water splitting because of its low cost,high activity,and durability.In addition,the solar-driven water electrolyzer using S-NiFeOOH as a bifunctional electrocatalyst affords the opportunity for developing effective and feasible solar power systems in the future.

Enhancing the stability of Ni Fe-layered double hydroxide nanosheet array for alkaline seawater oxidation by Ce doping

Electrocatalytic hydrogen production from seawater holds enormous promise for clean energy generation.Nevertheless,the direct electrolysis of seawater encounters significant challenges due to poor anodic stability caused by detrimental chlorine chemistry.Herein,we present our recent discovery that the incorporation of Ce into Ni Fe layered double hydroxide nanosheet array on Ni foam(Ce-Ni Fe LDH/NF)emerges as a robust electrocatalyst for seawater oxidation.During the seawater oxidation process,CeO_(2)is generated,effectively repelling Cl^(-)and inhibiting the formation of Cl O-,resulting in a notable enhancement in the oxidation activity and stability of alkaline seawater.The prepared Ce-Ni Fe LDH/NF requires only overpotential of 390 m V to achieve the current density of 1 A cm^(-2),while maintaining long-term stability for 500 h,outperforming the performance of Ni Fe LDH/NF(430 m V,150 h)by a significant margin.This study highlights the effectiveness of a Ce-doping strategy in augmenting the activity and stability of materials based on Ni Fe LDH in seawater electrolysis for oxygen evolution.

Effects of phosphate precursors on morphology and oxygen evolution reaction activity of NiFe(oxy)hydroxide on nickel foams

NiFe(oxy)hydroxides nanosheets were synthesized on nickel foams via co-precipitation and electrochemical activation. It is found that the phosphate precursors(Na_(3)PO_(4), Na_(2)HPO_(4)and NaH_(2)PO_(4)) have diverse effects on the morphology and thus the oxygen evolution reaction activity of the formed final catalysts. The resulting NiFe(oxy)hydroxides nanosheets prepared with Na_(2)HPO_(4)demonstrate a low overpotential of 205 m V to achieve a current density of 50 mA/cm^(2) with a Tafel slope down to 30 mV/dec in 1 mol/L KOH, and remain stable for 20 h during stability test.

Anchoring Active Sites by Pt_(2)FeNi Alloy Nanoparticles on NiFe Layered Double Hydroxides for Efficient Electrocatalytic Oxygen Evolution Reaction

Strategy of anchoring alloy nanoparticles made up of the efficient catalytic element(e.g.,Ni,Fe)on dodecyl sulfate(DS^(-))-intercalated NiFe layered double hydroxides(DS^(-)-NiFe LDH)obtained by a convenient one-step hydrothermal coprecipitation method for essentially enhancing oxygen evolution reaction(OER)performance was proposed.The results of structural characterization indicate Pt_(2)FeNi alloy nanoparticles evenly distribute on the surface of DS^(-)-NiFe LDH.The sizes of the Pt_(2)FeNi nanoparticles,closely related to their OER performance,could be wellcontrolled by adjusting the amount of H;PtCl;addition.The composite structure of as-prepared product was stable during processes of synthesis,exfoliation,self-assembly,and subsequent electrocatalytic OER.Rigorous electrochemical test proving the contributing catalytic active sites was located at the interface between Pt_(2)FeNi and DS^(-)-NiFe LDH,and the Ni and Fe were the major active elements while O atoms are adsorption sites.The formation of Pt_(2)FeNi nanoparticles could greatly prompt the reduction of Tafel slope.The best-performing Pt_(2)FeNi/DS^(-)-NiFe LDH with a Pt content of 0.98 wt%achieved low overpotential of 204 mV at 10 mA cm^(-2)and 262 mV at 50 mA cm^(-2).This work provides a convenient and effective strategy to create additional active sites for enhancing OER performance of NiFe LDH and make contribution to its wide application.

Promoting surface reconstruction of NiFe layered double hydroxides via intercalating[Cr(C_(2)O_(4))_(3)]^(3-)for enhanced oxygen evolution

Rationally manipulating surface reconstruction of catalysts for water oxidation,inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges.Herein,the introduction of[Cr(C_(2)O_(4))_(3)]^(3-)into NiFe LDHs by intercalation engineering to promote surface reconstruction achieves an advanced oxygen evolution reaction(OER)activity.In view of the weak electronegativity of Cr^(3+) in[Cr(C_(2)O_(4))_(3)]^(3-),the intercalation of[Cr(C_(2)O_(4))_(3)]^(3-)is expected to result in an electron-rich structure of Fe sites in NiFe LDHs,and higher valence state of Ni can be formed with the charge transfer between Fe and Ni.The optimized electronic structure of NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs with more active Ni^(3+) species and the expedited dynamic generation of Ni^(3+) (Fe)OOH phase during the OER process contributed to its excellent catalytic property,revealed by in situ X-ray absorption spectroscopy,Raman spectroscopy,and quasi-in situ X-ray photoelectron spectroscopy.With the modulated electronic structure of metal sites,NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs exhibited promoted OER property with a lower overpotential of 236 mV at the current density of 10 mA cm^(-2).This work illustrates the intercalation of conjugated anion to dynamically construct desired Ni^(3+) sites with the optimal electronic environment for improved OER electrocatalysis.

NiFe-LDH@Cu_(2)O/PAN光催化纤维的制备及性能研究

针对Cu_(2)O光催化活性较低,粉末光催化剂不易回收及重复使用性差等问题,采用静电纺丝方法制备NFC/PAN光催化纤维;通过引入可在其夹层中容纳阴离子的层状双氢氧化物,用NiFe-LDH对Cu_(2)O进行改性,并将其负载于PAN纤维,使用扫描电子显微镜、能谱仪、万能试验机、紫外可见吸收光谱等测试方法,评价不同Ni_(3)Fe_(1)-LDH@Cu_(2)O添加量对光催化纤维的性能影响。指出:在可见光照射60 min后,NFC质量百分比为5%的Ni_(3)Fe_(1)-LDH@Cu_(2)O/PAN对亚甲基蓝的降解效果最佳,达到91.7%,且其比表面积为76.3 cm^(2)/g,具有一定力学稳定性,重复使用5次后其降解率依旧达85%以上;5%Ni_(3)Fe_(1)-LDH@Cu_(2)O/PAN光催化效果在短时间可达到高效率,其光催化纤维降解速率常数最大,为0.0226,拉伸断裂强力提高3.35倍。

Electrochemical deposited amorphous FeNi hydroxide electrode for oxygen evolution reaction

The electrodeposition approach is significant in electrode fabrication for practical application.Herein,the electrodeposited amorphous NiFe hydroxide species for oxygen evolution reaction (OER) in water splitting reaction is demonstrated by revealing the synergistic effect influenced by the support electrode of Fe and Ni foil and the contents of Fe and Ni in the electrolyte.All the electrodeposited samples have an amorphous structure and similar profiles of binding energy and chemical states for Fe and Ni as characterized by the spectroscopic techniques.While the support effect and Fe/Ni synergistic effect are indeed observed for the varied catalytic performances observed for the different electrodes;the Ni foil supported catalyst exhibits much higher performance than that of the Fe foil supported catalyst,and the different redox potentials of Ni species in the different Fe/Ni electrode resulting from the Fe–Ni synergism are observed in the cyclic voltammetry curve analysis.The surface roughness and the electrochemical surface area are also influenced by the support effect and the Fe/Ni ratio in the plating electrolyte.The optimal electrode shows a very low overpotential of~200 mV to reach 10 mA cm^(-2),and very high catalytic stability by the consecutive cyclic voltammetry measurements and 20 h stability test.Though it has the largest electrochemical surface area,the highest catalytic efficiency for these active sites is also indicated by the specific activity and turnover frequency polarization curves.The current work shows the effective experience for the electrodeposited Fe/Ni based catalysts in large-scale fabrication,which can be more practical for hydrogen generation in the alkaline water electrolysis.

NiFe layered double-hydroxide nanoparticles for efficiently enhancing performance of BiVO_4 photoanode in photoelectrochemical water splitting

A bismuth vanadate(BiVO4)photoanode with a cocatalyst consisting of NiFe layered double‐hydroxide(NiFe‐LDH)nanoparticles was fabricated for photoelectrochemical(PEC)water splitting.NiFe‐LDH nanoparticles,which can improve light‐absorption capacities and facilitate efficient hole transfer to the surface,were deposited on the surface of the BiVO4 photoanode by a hydrothermal method.All the samples were characterized using X‐ray diffraction,scanning electron microscopy,and diffuse‐reflectance spectroscopy.Linear sweep voltammetry and current‐time plots were used to investigate the PEC activity.The photocurrent response of NiFe‐LDH/BiVO4 at 1.23 V vs the reversible hydrogen electrode was higher than those of Ni(OH)2/BiVO4,Fe(OH)2/BiVO4 and pure BiVO4 electrodes under visible‐light illumination.NiFe‐LDH/BiVO4 also gave a superior PEC hydrogen evolution performance.Furthermore,the stability of the NiFe‐LDH/BiVO4 photoanode was excellent compared with that of the bare BiVO4 photoanode,and offers a novel method for solar‐assisted water splitting.

Chelation-mediated in-situ formation of ultrathin cobalt(oxy)hydroxides on hematite photoanode towards enhanced photoelectrochemical water oxidation

In this work,a facile chelation-mediated route was developed to fabricate ultrathin cobalt(oxy)hydroxides(CoOOH)nanosheets on hematite photoanode(Fe_(2)O_(3)).The route contains two steps of the adsorption of[Co-EDTA]^(2-)species on Fe_(2)O_(3) nanorod array followed by the hydrolysis in alkaline solution.The resulting CoOOH/Fe_(2)O_(3) exhibits a remarkably improved photocurrent density of 2.10 mA cm^(-2) at 1.23 V vs.RHE,which is ca.2.8 times that of bare Fe_(2)O_(3).In addition,a negative shift of onset potential ca.200 mV is achieved.The structural characterizations reveal the chelate EDTA plays important roles that enhance the adsorption of Co species and the formation of contact between CoOOH and Fe_(2)O_(3).(Photo)electrochemical analysis suggests,besides providing active sites for water oxidation,CoOOH at large extent promotes the charge separation and the charge transfer via passivating surface states and suppressing charge recombination.It also found CoOOH possesses some oxygen vacancies,which could act as trapping centers for photogenerated holes and facilitate the charge separation.Intensity modulated photocurrent spectroscopy(IMPS)shows that,under low applied potential the water oxidation mainly occurs on CoOOH,while under high applied potential the water oxidation could occur on both CoOOH and Fe_(2)O_(3).The findings not only provide an efficient strategy for designing ultrathin(oxy)hydroxides on semiconductors for PEC applications but also put forward a new insight on the role of CoOOH during water oxidation.

NiFe水滑石纳米片阵列负载Ru用于提升碱性电催化析氢和析氧性能

通过离子交换的方式将Ru负载到NiFe水滑石(LDH)纳米阵列表面得到(Ru/NiFe LDH),Ru的引入显著提升了NiFe LDH的活性比表面积,暴露了更多的活性位点,同时调控了其电子结构,大大提升了其本征催化活性。在碱性条件下,催化析氢反应时仅需50 mV的过电位即可达到10 mA·cm^(-2)的电流密度,Tafel斜率为52.3 mV·dec^(-1)。而相同条件下原始NiFe LDH达到10mA·cm^(-2)的电流密度则需要226 mV的过电位,Tafel斜率为157.5 mV·dec^(-1)。同时制备的Ru/NiFe LDH也展现出了良好的析氧催化活性,在50 mA·cm^(-2)的电流密度下,过电位仅为231 mV,而NiFe LDH则需237 mV。Ru/NiFe LDH在长时间的电催化条件下依然能保持良好的工作稳定性。

Ag掺杂NiFe层状双氢氧化物应用于电催化析氢研究

开发廉价高效的催化剂是发展电解水产业的关键。层状双氢氧化物(LDH)在电催化析氧反应中表现出优异的性能,但这类催化剂在析氢反应中表现出的电化学性能并不好。本文通过将Ag元素掺杂在NiFe-LDH纳米片阵列中,获得了优异的析氢性能。结果表明,在1 mol/L KOH溶液中,电流密度达到10 mA·cm^(-2)所需的过电位仅为73 mV,且塔菲尔斜率为61.3 mV·dacade^(-1)。在800 mA·cm^(-2)的大电流密度下过电位仅为493 mV,明显低于商用铂碳催化剂。在长达30 h稳定性测试后仍保持90%以上电化学性能。催化性能的改善归因于Ag掺杂NiFe-LDH使纳米片尺寸减小和比表面积增加,有效提升产氢动力学并改善电子传输,从而优化NiFe-LDH的电催化析氢性能。

超薄超小镍铁水滑石的声悬浮制备

开发高效、低成本的清洁能源,有助于降低CO_(2)排放。电催化分解水产氢产氧或许可实现未来对清洁能源的需求。在诸多纳米材料中,超薄二维纳米材料因其可暴露更多的活性位点、具有更高的比表面积等特点,在电催化反应中表现出优异的性能。镍铁水滑石(NiFe-LDH)是非常有前景的过渡金属电催化分解水产氧反应(OER)催化剂。采用水热法制备Ni_(x)Fe_(1)-LDH(x=1,2,3)前体,利用超声悬浮剥离法实现超薄超小镍铁水滑石纳米片的快速制备。声悬浮法利用超声波发射端和反射端间产生的高强度声辐射力来抵消样品的重力,进而使样品被悬浮。超声波反复叠加形成的高声强驻波,更易实现超薄超小纳米材料的快速制备。研究发现,通过超声悬浮技术可实现仅用20μL甲酰胺在20 min内成功将Ni_(1)Fe_(1)-LDH前体从横向尺寸为1500 nm、厚度为25.66 nm剥离为分散较为均匀、横向尺寸约10 nm、厚度低至0.649 nm的超薄超小镍铁水滑石纳米片,并具有优异的OER性能。不同物质的量比的镍铁水滑石随超声悬浮时间逐渐增加,OER性能逐渐提高。其中,当电流密度达10 mA/cm^(2)时,Ni_(1)Fe_(1)-LDH-20 min的过电位低至309 mV,相比于Ni_(1)Fe_(1)-LDH前体的过电位673 mV,降低了364 mV,其塔菲尔斜率也相应从137 mV/dec降至67 mV/dec,电化学活性表面积增大了2.4倍。与其他过渡金属基催化剂相比,在OER中表现出优异的性能。

A novel septenary high-entropy(oxy)hydroxide electrocatalyst for boosted oxygen evolution reaction

High-entropy materials(HEMs)have attracted extensive attention in the field of electrochemical catal-ysis due to their unique properties.However,the preparation of high-entropy catalysts typically relies on high-temperature,energy-intensive,and time-consuming synthesis methods due to their compositional complexity.In this study,a facile low-temperature electrochemical reconstruction approach is adopted to synthesize Ag-decorated septenary Co-Cu-Fe-Mo-Zn-Ag-Ru high-entropy(oxy)hydroxide electro-catalysts for oxygen evolution reaction(OER).By introducing Ag and Ru elements and implanting Ag nanoparticles to co-regulate the electronic structure of the catalysts,the as-prepared catalyst achieves remarkable OER performance with a low overpotential of 298 mV at 100 mA/cm^(2)and a small Tafel slope of 30.1 mV/dec in 1 mol/L KOH.This work offers a valuable strategy for developing high-performance high-entropy OER electrocatalysts.

Towards a new avenue for rapid synthesis of electrocatalytic electrodes via laser-induced hydrothermal reaction for water splitting

Electrochemical production of hydrogen from water requires the development ofelectrocatalysts that are active,stable,and low-cost for water splitting.To address these challenges,researchers are increasingly exploring binder-free electrocatalytic integratedelectrodes (IEs) as an alternative to conventional powder-based electrode preparation methods,for the former is highly desirable to improve the catalytic activity and long-term stability for large-scale applications of electrocatalysts.Herein,we demonstrate a laser-inducedhydrothermal reaction (LIHR) technique to grow NiMoO4nanosheets on nickel foam,which is then calcined under H2/Ar mixed gases to prepare the IE IE-NiMo-LR.This electrode exhibits superior hydrogen evolution reaction performance,requiring overpotentials of 59,116 and143 mV to achieve current densities of 100,500 and 1000 mA·cm-2.During the 350 h chronopotentiometry test at current densities of 100 and 500 m A·cm-2,the overpotentialremains essentially unchanged.In addition,NiFe-layered double hydroxide grown on Ni foam is also fabricated with the same LIHR method and coupled with IE-NiMo-IR to achieve water splitting.This combination exhibits excellent durability under industrial current density.The energy consumption and production efficiency of the LIHR method are systematicallycompared with the conventional hydrothermal method.The LIHR method significantly improves the production rate by over 19 times,while consuming only 27.78%of the total energy required by conventional hydrothermal methods to achieve the same production.

Regulate electric double layer for one-step synthesize and modulate the morphology of(oxy)hydroxides

FeOOH have received considerable attention due to their natural abundance and cost-effectiveness.Despite the significant progress achieved,the one-step synthesis of integrated FeOOH is still a major challenge.Meanwhile,the current research on FeOOH catalyst still suffers from the unclear mechanism of controlling morphology.Here,density functional theory(DFT)calculations and X-ray photoelectron spectroscopy(XPS)demonstrated the strong electron-capturing and hydrogen absorption ability of Co in FeOOH,which further promotes the formation and stabilization of FeOOH.We used a one-step electrodeposition method to synthesize Co introduced FeOOH integrated electrocatalyst and propose to introduce ions with different valence states to regulate the morphology of FeOOH by precise modulation of electric double layer(EDL)composition and thickness.The prepared Co-FeOOH-K^(+)has a larger electrochemically active surface area(ECSA)(325 cm^(2))and turnover frequency(TOF)value(0.75 s^(-1)).In the electrochemical experiments of an alkaline anion exchange membrane electrolyzer,Co-FeOOH-K^(+)shows better oxygen evolution performance than commercial RuO_(2) under industrial production conditions and has good industrial application prospects.

自支撑NiFe LDHs@Co-OH-CO_(3)纳米棒阵列电极用于碱性阴离子交换膜电解水

开发高效耐用的电极对碱性阴离子交换膜电解水(AEMWEs)制氢至关重要。在这项研究中,我们展示了一种高效且稳定的自支撑NiFe LDHs@Co-OH-CO_(3)/NF纳米棒阵列电极分别用于析氧反应(OER)和AEMWE的阳极。在这项工作中,我们将2D的镍铁层状双金属氢氧化物纳米片(NiFe LDHs)原位生长在1D的碱式碳酸钴纳米线上(Co-OH-CO_(3)/NF),最终得到独特的纳米棒阵列复合结构电极。在三电极体系中,自支撑NiFe LDHs@Co-OH-CO_(3)/NF对OER具有良好的催化活性,在1 mol·L^(-1)KOH中,当电流密度为20 m A·cm^(-2)时,过电位为215 mV。当自支撑NiFe LDHs@Co-OH-CO_(3)/NF作为AEMWE的阳极(70℃,1 mol·L^(-1)KOH),在电流密度为0.5 A·cm^(-2)时,电解电压为1.72 V,并且具有较好的稳定性。进一步的实验表征结果显示了自支撑NiFe LDHs@Co-OH-CO_(3)/NF的优异性能是其具有特殊的形貌结构。这是由于纳米棒阵列电极的三维分层结构可以有效防止纳米片团聚,从而有利于电子转移,为水分解提供大量的边缘活性位点。

Sulfide@hydroxide core–shell nanostructure via a facile heating-electrodeposition method for enhanced electrochemical and photoelectrochemical water oxidation

Designing low-cost,easy-fabricated,highly stable and active electrocatalysts for oxygen evolution reaction(OER) is crucial for electrochemical(EC) and solar-driven photoelectrochemical(PEC) water splitting.By using a facile heating-electrodeposition method,here we fabricated a porous but crystalline Fe-doped Ni3 S2.A thin porous surface NiFe hydroxide layer(~10 nm) is then formed through OER-running.By virtue of the core Fe-doped Ni3 S2 with good conductivity and the shell NiFe hydroxide surface with good electrocatalytic activity,the core-shell nanostructure on Ni foam exhibits excellent OER activity in 1 M NaOH,needing only 195 and 230 mV to deliver 10 and 100 mA/cm^(2),respectively,much more superior to those of 216 and 259 mV for the sample deposited under normal temperature.The enhanced photo-response of the sulfide@hydroxide core-shell structure was also demonstrated,due to the efficient transfer of photo-generated carriers on the core/shell interface.More interestingly,it shows a good compatibility with Si based photoanode,which exhibits an excellent PEC performance with an onset potential of 0.86 V vs.reversible hydrogen electrode,an applied bias photon-to-current efficiency of 5.5% and a durability for over 120 h under AM 1.5 G 1 sun illumination,outperforming the state-of-the-art Si based photoanodes.

Nanopore-rich NiFe LDH targets the formation of the high-valent nickel for enhanced oxygen evolution reaction

Nickel-iron layered double hydroxides(NiFe LDHs)represent a promising candidate for oxygen evolution reaction(OER),however,are still confronted with insufficient activity,due to the slow kinetics of electrooxidation of Ni^(2+)cations for the high-valent active sites.Herein,nanopore-rich NiFe LDH(PR-NiFe LDH)nanosheets were proposed for enhancing the OER activity together with stability.In the designed catalyst,the confined nanopores create abundant unsaturated Ni sites at edges,and decrease the migration distance of protons down to the scale of their mean free path,thus promoting the formation of high-valent Ni^(3+)/^(4+)active sites.The unique configuration further improves the OER stability by releasing the lattice stress and accelerating the neutralization of the local acidity during the phase transformation.Thus,the optimized PR-NiFe LDH catalysts exhibit an ultralow overpotential of 278 mV at 10 mA∙cm^(−2)and a small Tafel slope of 75 mV∙dec^(−1),which are competitive among the advanced LDHs based catalysts.Moreover,the RP-NiFe LDH catalyst was implemented in anion exchange membrane(AEM)water electrolyzer devices and operated steadily at a high catalytic current of 2 A over 80 h.These results demonstrated that PR-NiFe LDH could be a viable candidate for the practical electrolyzer.This concept also provides valuable insights into the design of other catalysts for OER and beyond.

Heterointerface of all-alkynyl-protected Au_(28) nanoclusters anchored on NiFe-LDHs boosts oxygen evolution reaction:a case to unravel ligand effect

Ultrasmall Au nanoclusters have been proven to effectively enhance the catalytic performance of NiFe layered double hydroxides(NiFe-LDHs)toward oxygen evolution reaction(OER),yet the surface ligand effect of the Au nanoclusters still remains elusive.Herein,a systematic study is reported to examine the OER performance of NiFe-LDHs supported atom-precise all alkynyl-protected[Au_(28)(~tBuC≡C)17]~-nanoclusters(Au_(28)-Alkynyl in short)and thiolate-protected Au_(28)(TBBT)_(20)(TBBT=4-tert-butylbenzene thiol)counterp arts(Au_(28)-Thiolate in short).The Au_(28)-Alkynyl cluster has characteristic absorbance feature,and its composition is verified by mass spectrometry.It possesses a drastically different structure from the reported mixed ligand protected Au_(28)nanoclusters.Interestingly,the NiFe-LDHs loaded with Au_(28)-Alkynyl exhibited a superior OER performance than the sample loaded with Au28-Thiolate under the same conditions,evidenced by a smaller overpotential of 205 mV at the current density of 10 mA·cm^(-2)and a lower Tafel slope value of 41.0 mV·dec^(-1)in 1 mol·L^(-1)KOH.Such excellent performance is attributed to the interfaces created between the NiFe-LDHs and the Au nanoclusters,as density functional theory calculations reveal that more significant charge transfer occurs in Au_(28)-Alkynyl/NiFeLDHs catalyst,and more importantly,the energy barrier of the potential-determining step in the OER process for Au28-Alkynyl/NiFe-LDHs is much lower than that of Au28-Thiolate/NiFe-LDHs hence favors the electrocatalytic reaction.

Regulating the electronic structure of NiFe layered double hydroxide/reduced graphene oxide by Mn incorporation for high-efficiency oxygen evolution reaction

The development of highly efficient and costeffective oxygen evolution reaction(OER)electrocatalysts for renewable energy systems is vitally essential.Modulation of the electronic structure through heteroatom doping is considered as one of the most potential strategies to boost OER performances.Herein,a rational design of Mn-doped NiFe layered double hydroxide/reduced graphene oxide(Mn-NiFe LDH/rGO)is demonstrated by a facile hydrothermal approach,which exhibits outstanding OER activity and durability.Experimental results and density functional theory(DFT)calculations manifest that the introduction of Mn can reprogram the electronic structure of surface active sites and alter the intermediate adsorption energy,consequently reducing the potential limiting activation energy for OER.Specifically,the optimal Mn-NiFe LDH/rGO composite shows an enhanced OER performance with an ultralow overpotential of 240 mV@10 mA cm^(-2),Tafel slope of 40.0 mV dec^(-1) and excellent stability.Such superior OER activity is comparable to those of the recently reported state-of-the-art OER catalysts.This work presents an advanced strategy for designing electrocatalysts with high activity and low cost for energy conversion applications.