Self-derivation and reconstruction of silver nanoparticle reinforced cobalt-nickel bimetallic hydroxides through interface engineering for overall water splitting

Designing efficient and long-lasting non-metal electrocatalysts is an urgent task for addressing the issue of kinetic hysteresis in electrochemical oxidation reactions.The bimetallic hydroxides,catalyzing the oxygen evolution reaction(OER),have significant research potential because hydroxide reconstruction to generate an active phase is a remarkable advantage.Herein,the complete reconstruction of ultrathin CoNi(OH)_(2) nanosheets was achieved by embedding Ag nanoparticles into the hydroxide to induce a spontaneous redox reaction(SRR),forming heterojunction Ag@CoNi(OH)_(2) for bifunctional hydrolysis.Theoretical calculations and in situ Raman and ex situ characterizations revealed that the inductive effect of the Ag cation redistributed the charge to promote phase transformation to highly activate Ag-modified hydroxides.The Co-Ni dual sites in Co/NiOOH serve as novel active sites for optimizing the intermediates,thereby weakening the barrier formed by OOH^*.Ag@CoNi(OH)_(2) required a potential of 1.55 V to drive water splitting at a current density of 10 mA cm^(-2),with nearly 98.6% Faraday efficiency.Through ion induction and triggering of electron regulation in the OER via the synergistic action of the heterogeneous interface and surface reconstruction,this strategic design can overcome the limited capacity of bimetallic hydroxides and bridge the gap between the basic theory and industrialization of water decomposition.

Ultrafast Synthesis of Metal-Layered Hydroxides in a Dozen Seconds for High-Performance Aqueous Zn(Micro-)Battery

Efficient synthesis of transition metal hydroxides on conductive substrate is essential for enhancing their merits in industrialization of energy storage field.However,most of the synthetic routes at present mainly rely on traditional bottom-up method,which involves tedious steps,time-consuming treatments,or additional alkaline media,and is unfavorable for high-efficiency production.Herein,we present a facile,ultrafast and general avenue to synthesize transition metal hydroxides on carbon substrate within 13 s by Joule-heating method.With high reaction kinetics caused by the instantaneous high temperature,seven kinds of transition metal-layered hydroxides(TM-LDHs)are formed on carbon cloth.Therein,the fastest synthesis rate reaches~0.46 cm^(2)s^(-1).Density functional theory calculations further demonstrate the nucleation energy barriers and potential mechanism for the formation of metal-based hydroxides on carbon substrates.This efficient approach avoids the use of extra agents,multiple steps,and long production time and endows the LDHs@carbon cloth with outstanding flexibility and machinability,showing practical advantages in both common and micro-zinc ion-based energy storage devices.To prove its utility,as a cathode in rechargeable aqueous alkaline Zn(micro-)battery,the NiCo LDH@carbon cloth exhibits a high energy density,superior to most transition metal LDH materials reported so far.

Layered double hydroxides as electrode materials for flexible energy storage devices

To prevent and mitigate environmental degradation,high-performance and cost-effective electrochemical flexible energy storage systems need to be urgently developed.This demand has led to an increase in research on electrode materials for high-capacity flexible supercapacitors and secondary batteries,which have greatly aided the development of contemporary digital communications and electric vehicles.The use of layered double hydroxides(LDHs)as electrode materials has shown productive results over the last decade,owing to their easy production,versatile composition,low cost,and excellent physicochemical features.This review highlights the distinctive 2D sheet-like structures and electrochemical characteristics of LDH materials,as well as current developments in their fabrication strategies for expanding the application scope of LDHs as electrode materials for flexible supercapacitors and alkali metal(Li,Na,K)ion batteries.

Self-supported ultrathin NiCo layered double hydroxides nanosheets electrode for efficient electrosynthesis of formate

Electrochemical CO_(2)reduction into energy-carrying compounds,such as formate,is of great importance for carbon neutrality,which however suffers from high electrical energy input and liquid products crossover.Herein,we fabricated self-supported ultrathin NiCo layered double hydroxides(LDHs)electrodes as anode for methanol electrooxidation to achieve a high formate production rate(5.89 mmol h^(-1)cm^(-2))coupled with CO_(2)electro-reduction at the cathode.A total formate faradic efficiency of both anode for methanol oxidation and cathode for CO_(2)reduction can reach up to 188%driven by a low cell potential of only 2.06 V at 100 mA cm^(-2)in membrane-electrode assembly(MEA).Physical characterizations demonstrated that Ni^(3+)species,formed on the electrochemical oxidation of Ni-containing hydroxide,acted as catalytically active species for the oxidation of methanol to formate.Furthermore,DFT calculations revealed that ultrathin LDHs were beneficial for the formation of Ni^(3+)in hydroxides and introducing oxygen vacancy in NiCo-LDH could decrease the energy barrier of the rate-determining step for methanol oxidation.This work presents a promising approach for fabricating advanced electrodes towards electrocatalytic reactions.

ZnAl-LDHs覆膜改性湿地基质强化氮磷吸附性能

传统湿地基质存在吸附作用单一的缺陷,采用LDHs覆膜定向改性具有一定氨氮吸附优势的人工湿地基质,通过冷场发射扫描电镜、X射线衍射仪对改性基质进行物理表征,研究无机磷(In-P)溶液初始浓度、吸附时间等因素对改性基质吸附In-P的影响,结合吸附等温线和吸附动力学分析除磷特性及吸附机理。结果表明,ZnAl-LDHs改性蛭石拟合得到的最大吸附量达74.239 mg/g,高于同类改性的沸石(4.133 mg/g)和砖渣(11.937 mg/g);吸附强度和吸附容量(K f=5.022)均大于改性沸石(0.633)和改性砖渣(0.971);ZnAl-LDHs改性基质对In-P的吸附动力学与准二级动力学模型拟合度(R2>0.980)更高,以化学吸附为控制步骤的吸附过程为主。利用蛭石进行ZnAl-LDHs覆膜改性可实现氨氮与In-P的同步高效吸附,有望弥补传统人工湿地基质吸附功能单一的不足。

NiAl-LDHs电极材料的水热合成及其超级电容器电化学性能

超级电容器具有大充放电速率、良好的循环稳定性及高功率密度等优点,是一种新兴的绿色环保储能器件。采用简单的水热合成法制备镍铝层状双金属氢氧化物(NiAl-LDHs)超级电容器电极材料,探究不同镍铝比对其形貌组成及电化学性能的影响。所制备的Ni1Al1-LDHs电极材料在电流密度为1A/g时表现出378F/g的高比电容。以活性炭(AC)为负极组成的Ni1Al1-LDHs//AC非对称超级电容器在能量密度为27.5 Wh/kg时,具有1.4 kW/kg的高功率密度,表现出优异的电化学性能。

Boron separation by adsorption and flotation with Mg-Al-LDHs and SDBS from aqueous solution

Layered double hydroxides(LDHs)have been shown to be effective adsorbents for boron.However,solid-liquid separation is still a problem when separating boron from industrial radioactive waste liquid.In this research,three types of Mg-Al-LDHs including Mg-Al-LDH(NO_(3)^(-)),Mg-Al-LDH(Cl^(-))and Mg-Al-LDH(SO_(4)^(2-))were applied to adsorb boron,and moreover sodium dodecylbenzenesulfonate(SDBS)was used to float the LDH particles from aqueous solution after boron adsorption.The results showed that 60 min was sufficient for the equilibrium adsorption of the three LDHs.The boron adsorption capacity of three LDHs was determined as follows:Mg-Al-LDH(NO_(3)^(-))>Mg-Al-LDH(Cl^(-))>Mg-Al-LDH(SO_(4)^(2-)),and was 2.0,0.98 and 0.2 mmol·g^(-1),each ranging from 0 to 80 mmol·L^(-1)with the initial boron concentration.The efficiency of boron removal by Mg-Al-LDH(NO_(3)^(-))and SDBS can reach up to 89.7%.Furthermore,the boron flotation mechanism of SDBS and LDHs has been studied,since SDBS as a flotation agent can react with LDHs and penetrate into the interlayer of LDHs in addition to electrostatic attraction.Therefore,LDHs in solution can be floated onto the foam layer to be separated from the solution,and the clarified solution was obtained.The method is simple and promising for boron removal from aqueous solution.

Construction of CuNiAl-LDHs electrocatalyst with rich-Cu^(+)and—OH for highly selective reduction of CO_(2) to methanol

In this work,a high-performance CuNiAl-LDHs catalyst was innovatively synthesized for electrochemical carbon dioxide reduction(CO_(2)RR)of methanol(CH3OH)through the modulated synthesis of Cu-based layered double hydroxide(LDHs).It was found that the optimal CuNiAl-LDHs has superior CH3OH selectivity compared to CuAl-LDHs and CuMgAl-LDHs,with the Faraday efficiency(FE)of 76.4%for CH3OH generation at1.2 V.And their FE and current density(4.8 mA·cm^(2))remained stable during up to 24 h of electrolysis.Meanwhile,this study confirms the significant performance advantages of CuNiAlLDHs over their derived composite oxides.Series characterization further proves that the excellent catalytic performance of CuNiAl-LDHs is importantly associated with their richness in Cu+and hydroxyl group(-OH).The research expands the application fields of LDHs compounds.Meanwhile,the series of discoveries provide a new insight for the preparation of CH3OH by constructing CO_(2)RR.

Fabrication of highly dispersed carbon doped Cu-based oxides as superior selective catalytic oxidation of ammonia catalysts via employing citric acid-modified carbon nanotubes doping CuAl-LDHs

In this work,the CuAl-LDO/c-CNTs catalyst was fabricated via in situ oriented assembly of layered-double hydroxides(LDHs)and citric acid-modified carbon nanotubes(c-CNTs)followed by annealing treatment,and evaluated in the selective catalytic oxidation(SCO)of NH_(3)to N_(2).The CuAl-LDO/c-CNTs catalyst presented better catalytic performance(98%NH_(3)conversion with nearly 90%N_(2)selectivity at 513 K)than other catalysts,such as CuAlO_(x)/CNTs,CuAlO_(x)/c-CNTs and CuAl-LDO/CNTs.Multiple characterizations were utilized to analyze the difference of physicochemical properties among four catalysts.XRD,TEM and XPS analyses manifested that CuO and Cu_(2)O nanoparticles dispersed well on the surface of the Cu Al-LDO/c-CNTs catalyst.Compared with other catalysts,larger specific surface area and better dispersion of CuAl-LDO/c-CNTs catalyst were conducive to the exposure of more active sites,thus improving the redox capacity of the active site and NH_(3)adsorption capacity.In-situ DRIFTS results revealed that the internal selective catalytic reduction(iSCR)mechanism was found over CuAl-LDO/c-CNTs catalyst.

Identification and comparison of the local physicochemical structures of transition metal-based layered double hydroxides for high performance electrochemical oxygen evolution reactions

Layered double hydroxides(LDHs) have attracted considerable attention as a cost effective alternative to the precious iridium-and ruthenium-based electrocatalysts for an oxygen evolution reaction(OER),a bottleneck of water electrolysis for sustainable hydrogen production.Despite their excellent OER performance,the structural and electronic properties of LDHs,particularly during the OER process,remain to be poorly understood.In this study,a series of LDH catalysts is investigated through in situ X-ray absorption fine structure analyses and density functional theory(DFT) calculations.Our experimental results reveal that the LDH catalyst with equal amounts of Ni and Fe(NF-LDH) exhibits the highest OER activity and catalytic life span when compared with its counterparts having equal amounts of Ni and Co(NC-LDH)and Ni only(Ni-LDH).The NF-LDH shows a markedly enhanced OER kinetics compared to the NC-LDH and the Ni-LDH,as proven by the lower overpotentials of 180,240,and 310 mV,respectively,and the Tafel slopes of 35.1,43.4,and 62.7 mV dec^(-1),respectively.The DFT calculations demonstrate that the lowest overpotential of the NF-LDH is associated with the active sites located at the edge planes of NF-LDH in contrast to those located at the basal planes of Ni-LDH and NC-LDH.The current study pinpoints the active sites on various LDHs and presents strategies for optimizing the OER performance of the LDH catalysts.

Efficient C-N coupling in electrocatalytic urea generation on copper carbonate hydroxide electrocatalysts

Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen electrode.Our thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~*NHO.This work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.

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.

CO2 Transformation at Controlled Temperature with Lithium Hydroxide Solution and Metallic Lithium

This paper presents a study on CO2 atmospheric transformation which was reacted directly with lithium hydroxide solution and metallic lithium. This solution was obtained through the reaction between metallic lithium and deionized water where hydrogen is produced and by exposing the metal at ambient conditions. In the transformation process, atmospheric CO2 gas reacts directly with LiOH solution, in both cases, the CO2 transformation kinetics was different. For this purpose, reactions between CO2 and LiOH solution were carried out under controlled temperature and the second process only with metallic lithium, which was exposed at room temperature, however, in these two processes lithium carbonate oxide was formed and identified. According to the results, the efficiency in CO2 transformation is a function of temperature value which was variable until completely obtaining the by-product, its XRD characterization indicated the formation only of Li2CO3 in both procedures. Under laboratory conditions lithium compounds selectively reacted with CO2. In the same way, there is an alternative procedure to obtain LiOH and Li2CO3 for different applications in various areas.

Clinical Value of Endodontic Patients Treated with Calcium Hydroxide Preparations

Objective: To investigate the clinical value of endodontics patients treated with calcium hydroxide preparation. Methods: The study cases were selected from the endodontics patients who visited our hospital during the period from January 2022 to December 2023, and 97 cases were randomly selected according to the numerical table method and divided into two groups. There were 49 cases in the control group and 48 cases in the experimental group. The control group received conventional therapy, while the experimental group received treatment with calcium hydroxide preparation, and the clinical value of the two different treatment modalities was observed and analyzed. Results: In the experimental group, 45 out of 48 patients (93.75%) showed effectiveness, compared to 39 out of 49 patients (79.59%) in the control group. The effectiveness rate was significantly higher in the experimental group (P < 0.05). Initially, the VAS scores between the two groups were similar (P > 0.05), but after 1 and 3 months of treatment, the scores decreased in both groups. However, the experimental group had a greater decrease, indicating lower pain levels (P < 0.05). The experimental group had fewer complications (8.33%) compared to the control group (24.49%), with a significant difference (P < 0.05). Satisfaction with treatment was higher in the experimental group (95.83%) compared to the control group (95.83%), resulting in an overall higher satisfaction rate in the experimental group (83.67%;P < 0.05). Conclusion: The treatment effect of endodontics with calcium hydroxide preparation is remarkable, which not only can effectively help patients to relieve their pain and reduce the incidence of complications but also plays an important role in improving patients’ satisfaction with treatment, which is worthwhile to be vigorously promoted in the clinic and learn from it.

类水滑石Ti/Li/Al-LDHs的制备及其CO_2吸附性能

采用共沉淀法制备了一系列新型的类水滑石Ti/Li/Al-LDHs材料,通过原子吸收光谱(AAS)、X射线衍射(XRD)、扫描电镜(SEM)、热重分析(TG)和傅里叶变换红外光谱(FT-IR)等技术对其进行了表征,研究了不同金属元素比例和焙烧温度对该Ti/Li/Al-LDHs材料的结构、形貌及其CO_2吸附性能的影响。结果表明,当Ti/Li/Al比为1∶3∶4时,水滑石Ti/Li/AlLDHs的结晶度最好,形貌最规整,而Ti/Li/Al比为1∶3∶2、300℃下焙烧后得到的Ti_1Li_3Al_2-LDHs_(300)的CO_2吸附性能最好。Ti_1Li_3Al_2-LDHs_(300)上CO_2吸附量可达53.5 mg/g,10次循环吸附后,CO_2吸附量仅下降了2.4%。

硼酸根插层的Ca-Al-LDHs的制备、表征和应用

以四水硝酸钙、六水硝酸铝、氢氧化钠及硼酸为原料,利用离子交换的方法合成硼酸根插层的Ca-AlLDHs,并对其进行初步表征。X射线衍射、电子扫描电镜分析和红外光谱测试表明合成出的硼酸根插层Ca-AlLDHs具有良好的层状结构,形貌呈片状,插入钙铝层板间的硼酸根具有BO_4^(5-)和BO_3^(3-)两种结构。以硬脂酸、钛酸酯偶联剂NDZ-311为改性剂,对合成出的硼酸根插层的Ca-Al-LDHs进行改性,并将改性后的硼酸根插层的LDHs粉体与乙烯-醋酸乙烯酯(EVA)材料进行混合得到复合塑料,通过测复合塑料的氧指数研究该种LDHs的阻燃效果。发现当改性硼酸根插层的LDHs粉体填充量为40%(质量分数)时,拉伸强度为9.68 MPa,断裂伸长率为663.3%,极限氧指数为27.2%。

Ni-Mg-Al-LDHs的制备及其催化酯化高酸原油脱酸的研究

采用尿素法和共沉淀法制备了Ni-Mg-Al-LDHs前驱体,在400℃煅烧,得Ni-Mg-Al-LDHs催化剂,研究其催化高酸原油酯化脱酸的效果。结果表明,反应时间为150 min,反应温度为220℃,醇/油体积比为0.05,催化剂与原油质量比为0.03时,可将原油酸度由5.82 mg KOH/g降至0.34 mg KOH/g。

微波场下纳米Mg-Al-LDHs及PO_4^(3-),P_2O_7^(4-)柱撑Mg-Al层状双氢氧化物的合成

用微波加热反应-变速滴加共沉淀法合成了[Mg-Al-CO3]纳米层状双氢氧化物,并以[Mg-Al-CO3]纳米层状双氢氧化物为前体,用微波加热反应-离子交换法制备了PO43-,P2O74-柱撑Mg-Al层状双氢氧化物。该法合成的[Mg-Al-CO3]纳米层状双氢氧化物的粒径约为10-40nm。讨论了微波和变速滴加碱液的速度对纳米层状双氢氧化物的合成的影响。用FT-IR、TEM与XRD对产物进行了表征,结果表明在微波加热反应的条件下可在短时间内用PO43-,P2O74-彻底交换CO32-。

Cu Al-LDHs/生物质炭的制备及对水中磷的去除

采用水热法制备铜铝层状双金属氢氧化物,负载在剑麻生物质炭上,得到CuAl-LDHs/生物质炭,通过SEM、BET、XRD和FTIR等对结构进行表征,考察了初始pH值、投加量、吸附时间和温度等对吸附除磷的影响,并讨论了吸附动力学与等温吸附特性。结果表明,制备的材料结晶度高、粒径小,平均孔径为4.37 nm;吸附动力学和吸附等温线分别符合准二级动力学方程和Langmuir吸附等温方程。在pH为8.0,温度25℃时,对磷的最大吸附容量可达78.56 mg/g。

牛磺酸和布洛芬插层MgAl-LDHs药物缓释材料制备及其结构研究

采用焙烧还原法制备了牛磺酸/层状双氢氧化物插层复合物(TAU-LDH)和布洛芬/层状双氢氧化物插层复合物(IBU-LDH)。研究了插层复合物中TAU和IBU在模拟人体内肠道pH值(pH=7.4)的磷酸缓冲溶液(PBS)中的缓释性能。XRD和FT-IR分析表明,TAU和IBU阴离子成功进入到LDHs层间形成插层复合物,IBU-LDH插层复合物的结晶性能优于TAU-LDH。UV-Vis分析表明,存在于LDHs层间的TAU和IBU在缓冲溶液中具有明显的缓释特性。复合物中的TAU 40 min释放85%,180 min释放完全;IBU 40 min释放88%,180 min释放完全。IBU-LDH插层复合物的药物缓释特性优于TAU-LDH插层复合物。