Methanol Tolerant Non-noble Metal Co-C-N Catalyst for Oxygen Reduction Reaction Using Urea as Nitrogen Source

A non-noble metal oxygen reduction reaction （ORR） catalyst labeled as Co-C-N（800） was synthesized by heat-treating a mixture of urea, cobalt chloride and acetylene black for 2 h at 800 ℃ in an inert nitrogen atmosphere. X-ray diffraction pattern indicates that a metallic β-Co is generated after the heat-treating process. The results from cyclic voltammograms show that the obtained Co-C-N（800） catalyst has good ORR catalytic activity in 0.5 mol/L H2SO4 solution. The catalyst is also good at methanol tolerance and stability in the acidic solution.

Progress on Platinum-Based Catalyst Layer Materials for H_(2)-PEMFC

The constant increase in energy demand and related environmental issues have made fuel cells an attractive technology as an alternative to conventional energy technologies.Like any technology,fuel cells face drawbacks that scientific society has been focused on to improve and optimize the overall technology.Thus,the cost is the main inhibitor for this technology due to the significantly high cost of the materials used in catalyst layers.The current discussion mainly focuses on the fundamental electrochemical half-cell reaction of hydrogen oxidation reaction(HOR)and oxygen reduction reaction(ORR)that are taking place in the catalyst layers consisting of Platinum-based and Platinum-non noble metals.For this purpose,studies from the literature are presented and analyzed by highlighting and comparing the variations on the catalytic activity within the experimental catalyst layers and the conventional ones.Furthermore,an economic analysis of the main platinum group metals(PGMs)such as Platinum,Palladium and Ruthenium is introduced by presenting the economic trends for the last decade.

Metal–Organic Framework-Derived Hollow Nanocubes as Stable Noble Metal-Free Electrocatalyst for Water Splitting at High Current Density

Alkaline water electrolysis is an environmentally friendly and promising approach to produce hydrogen.However,high cost,low efficiency,and poor stability are roadblocks to commercialization of electrocatalysts.This work aims to design and develop a highly efficient,durable,and cost-effective electrocatalyst toward water splitting through modifying metal–organic frameworks.The electrocatalytic performance and stability surpass those of noble metal benchmarks at high current density(1–10 A·cm^(−2)).Theoretical calculations and in situ Raman spectra reveal the electronic structure of the synthesized catalyst and the mechanism of the catalytic reaction process,which rationalizes that the high catalytic activity and stability at high current are attributed to the unique electronic structure of cobalt regulated by copper and the protection provided by carbon nanotubes formed in situ,respectively.In addition,this paper proposes that the desorption ability of the catalyst toward the products(H_(2)and O_(2)),rather than the adsorption ability toward the reactants(H^(+)or OH^(−)),is more important to the sustainable and stable electrochemical water splitting progress at high current density,which is a kinetic rather than thermodynamic dominating process.The findings provide alternative insights to design and employ high performance catalysts to fuel hydrogen production as a clean energy source to tackle the global energy crisis.

层状镨铈氢氧化物衍生纳米片负载金催化甘油氧化性能研究

采用低温均相沉淀和冷冻干燥法合成了镨掺杂层状氢氧化铈纳米片(LPr_(x)Ce_(1-x)H),以其为前体通过氨水沉积沉淀和热处理过程制备了LPr_(x)Ce_(1-x)H衍生纳米片负载金催化剂(Au/LPr_(x)Ce_(1-x)O)。利用X射线衍射(XRD)、透射电子显微镜(TEM)、高分辨透射电镜(HRTEM)和H_(2)程序升温还原技术(H_(2)-TPR)对材料的结构、微观形貌、还原特性进行了表征,并考察了Au/LPr_(x)Ce_(1-x)O催化剂在温和(90℃、1atm)条件下催化甘油选择性氧化反应的性能。

Hydroxylated metal–organic-layer nanocages anchoring single atomic cobalt sites for robust photocatalytic CO_(2) reduction

Assembly of two-dimensional(2D)metal–organic layers(MOLs)based on the hard and soft acid–base theorem represents an exquisite strategy for the construction of photocatalytic platforms in virtue of the highly exposed active sites,much improved mass transport,and greatly elevated stability.Herein,nanocages composed of MOLs are produced for the first time through a cosolvent approach utilizing zirconium-based UiO-66-(OH)2 as the structural precursor.To endow the catalytic activity for CO_(2) conversion,single atomic Co^(2+)sites are appended to the Zr-oxo nodes of the MOL cages,demonstrating a remarkable CO yield of 7.74 mmol·g^(-1)·h^(-1) and operational stability of 97.1%product retention after five repeated cycles.Such an outstanding photocatalytic performance is mainly attributed to the unique nanocage morphology comprising enormous 2D nanosheets for augmented Co^(2+)exposure and the abundant surface hydroxyl groups for local CO_(2) enrichment.This work underlines the tailoring of both metal–organic framework(MOF)morphology and functionality to boost the turnover rate of photocatalytic CO_(2) reduction reaction(CO_(2)RR).

Electrochemical removal of ammonium nitrogen in high efficiency and N_(2) selectivity using non-noble single-atomic iron catalyst

Ammonia nitrogen (NH_(4)^(+)-N) is a ubiquitous environmental pollutant,especially in offshore aquaculture systems.Electrochemical oxidation is very promising to remove NH_(4)^(+)-N,but suffers from the use of precious metals anodes.In this work,a robust and cheap electrocatalyst,iron single-atoms distributed in nitrogen-doped carbon (Fe-SAs/N-C),was developed for electrochemical removal of NH_(4)^(+)-N from in wastewater containing chloride.The FeSAs/N-C catalyst exhibited superior activity than that of iron nanoparticles loaded carbon(Fe-NPs/N-C),unmodified carbon and conventional Ti/IrO_(2)-TiO_(2)-RuO_(2)electrodes.And high removal efficiency (>99%) could be achieved as well as high N_(2)selectivity (99.5%) at low current density.Further experiments and density functional theory (DFT) calculations demonstrated the indispensable role of single-atom iron in the promoted generation of chloride derived species for efficient removal of NH_(4)^(+)-N.This study provides promising inexpensive catalysts for NH_(4)^(+)-N removal in aquaculture wastewater.

化学镀Ni-P镀层耐蚀性的研究进展

文章通过介绍化学镀Ni-P反应机理、耐蚀性机理和镀层封孔技术等理论知识,同时对化学镀Ni-P技术的稀土催化、多元金属共沉积和多层复合三大趋势进行了归纳,并对化学镀Ni-P技术未来的发展进行了展望。

Exploration of the oxygen transport behavior in non-precious metal catalyst-based cathode catalyst layer for proton exchange membrane fuel cells

High cost has undoubtedly become the biggest obstacle to the commercialization of proton exchange membrane fuel cells(PEMFCs),in which Pt-based catalysts employed in the cathodic catalyst layer(CCL)account for the major portion of the cost.Although nonprecious metal catalysts(NPMCs)show appreciable activity and stability in the oxygen reduction reaction(ORR),the performance of fuel cells based on NPMCs remains unsatisfactory compared to those using Pt-based CCL.Therefore,most studies on NPMC-based fuel cells focus on developing highly active catalysts rather than facilitating oxygen transport.In this work,the oxygen transport behavior in CCLs based on highly active Fe-N-C catalysts is comprehensively explored through the elaborate design of two types of membrane electrode structures,one containing low-Pt-based CCL and NPMCbased dummy catalyst layer(DCL)and the other containing only the NPMC-based CCL.Using Zn-N-C based DCLs of different thickness,the bulk oxygen transport resistance at the unit thickness in NPMC-based CCL was quantified via the limiting current method combined with linear fitting analysis.Then,the local and bulk resistances in NPMC-based CCLs were quantified via the limiting current method and scanning electron microscopy,respectively.Results show that the ratios of local and bulk oxygen transport resistances in NPMCbased CCL are 80%and 20%,respectively,and that an enhancement of local oxygen transport is critical to greatly improve the performance of NPMC-based PEMFCs.Furthermore,the activity of active sites per unit in NPMCbased CCLs was determined to be lower than that in the Pt-based CCL,thus explaining worse cell performance of NPMC-based membrane electrode assemblys(MEAs).It is believed that the development of NPMC-based PEMFCs should proceed not only through the design of catalysts with higher activity but also through the improvement of oxygen transport in the CCL.

Recent advances in carbonized non-noble metal–organic frameworks for electrochemical catalyst of oxygen reduction reaction

The non-noble metal oxygen reduction reaction(ORR) catalysts prepared by carbonization of metal–organic framework(MOF) have attracted more and more attentions in the fields of fuel cells and metal-air batteries due to their unique intrinsic advantages such as high catalytic activity, low price, simple synthesis and good adaptability. Different from the study of traditional high active noble metal catalysts, this review systematically summarizes recent developments on non-noble metal(Fe,Co, Cu, Ni, Mn and Mo) ORR catalysts prepared by various MOFs carbonization in different metal centers. The effects of synthesis strategies and pyrolysis conditions on the catalyst properties are discussed. Meanwhile, the key parameters of catalytic performances(including active sites, dispersed state and specific surface area) are discussed and the prospect is presented. It is expected that this review will provide effective guidance for future studies on carbonized non-noble MOFs for ORR electrochemical catalyst.

Comparative Studies of Non-noble Metal Modified Mesoporous M-Ni-CaO-ZrO2 （M=Fe, Co, Cu） Catalysts for Simulated Biogas Dry Reforming

The present work is aimed to improve the performance of Ni-based catalysts for biogas dry reforming by adding a second non-noble metal （Fe, Co, Cu） into a previously studied mesoporous Ni-CaO-ZrO2 nanocomposite. Biogas was simulated with equivalent methane and carbon dioxide for the dry reforming reaction. X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, N2 adsorption, temperature-programmed reduction （TPR）, thermogravi- metric analysis （TGA）, and transmission electron microscopy （TEM） measurements were taken to characterize the structural and textual properties of the bimetallic catalysts as well as the accumulated carbon deposition. The addition of Fe leads to a less ordering growth of mesopores of Fe-Ni-CaO-ZrO2 sample, and the existence of Cu results in a relatively larger portion of free NiO in Cu-Ni-CaO-ZrO2. Compared with Fe and Cu, the presence of Co could efficiently form a beneficial dual metal effect and enhance the strong metal support interaction between Ni and CaO-ZrO2, thus enhancing the activity and stability of the catalyst in biogas dry reforming reaction.

Non-noble metal single-atom catalysts with phosphotungstic acid(PTA)support:A theoretical study of ethylene epoxidation

Geometric and electronic structures of phosphotungstic acid(PTA)supported single transition metal atom(Fe,Co,Ni,Ru,Rh,Pd,Os,Ir and Pt)catalysts have been systematically investigated by using the first-principles theoretical methods.Possible reaction mechanism for ethylene epoxidation was explored.The most possible anchoring site for the single transition metal atom is the fourfold hollow site on PTA.As the non-noble metal Fe1-PTA system possesses considerable adsorption energies towards both O2 and C2H4,the strong bonding interaction between Fe1 and PTA cluster was analyzed.It is found that the electron transfers from Fe atom to PTA cluster and strong covalent metal-support interactions(CMSI)between the Fe 3 d orbitals and O 2 p orbitals of PTA lay the foundation of high stability.The proposed catalytic reaction mechanism for ethylene epoxidation on Fe1-PTA single-atom catalyst(SAC)includes three steps:the O2 adsorbs on Fe1-PTA via electron transfer;the first ethylene attacks the adsorbed O2 molecule on Fe1-PTA followed by the formation of C2H4O;finally,the O atom remained on Fe1-PTA reacts with a second ethylene to form the product and accomplish the catalytic cycle.The Fe1-PTA has high selectivity and catalytic activity for ethylene epoxidation via an Eley–Rideal mechanism with low energy barriers.A potentially competitive pathway for the formation of acetaldehyde is not kinetically favorable.These results provide insights for the development of highly efficient heterogeneous SACs for ethylene epoxidation with non-noble metals.

Stability and activity of carbon nanofiber-supported catalysts in the aqueous phase reforming of ethylene glycol

Nickel, cobalt, copper and platinum nanoparticles supported on carbon nano-fibers were evaluated with respect to their stability, catalytic activity and selectivity in the aqueous phase reforming of ethylene glycol （230 ℃, autogenous pressure, batch reactor）. The initial surface-specific activities for ethylene glycol reforming were in a similar range but decreased in the order of Pt （15.5 h-1 ） 〉Co（13.0 h 1 ） 〉Ni（5.2 h-1） while the Cu catalyst only showed low dehydrogenation activity. The hydrogen molar selectivity decreased in the order of Pt （53%）〉Co（21%）〉Ni （15%） as a result of the production of methane over the latter two catalysts. Over the Co catalyst acids were formed in the liquid phase while alcohols were formed over Ni and Pt. Due to the low pH of the reaction mixture, especially in the case of Co （as a result of the formed acids）, significant cobalt leaching occurs which resulted in a rapid deactivation of this catalyst. Investigations of the spent catalysts with various techniques showed that metal particle growth is responsible for the deactivation of the Pt and Ni catalysts. In addition, coking might also contribute to the deactivation of the Ni catalyst.

Density functional theory calculations on single atomic catalysis:Ti-decorated Ti3C2O2 monolayer(MXene)for HCHO oxidation

Formaldehyde(HCHO) is a common indoor pollutant, long-term exposure to HCHO may harm human health. Its efficient removal at mild conditions is still challenging. The catalytic oxidation of HCHO molecules on a single atomic catalyst, Ti-decorated Ti3C2O2(Ti/Ti3C2O2) monolayer, is investigated by performing the first principles calculations in this work. It demonstrates that Ti atoms can be easily well dispersed at the form of single atom on Ti3C2O2 monolayer without aggregation. For HCHO catalytic oxidation, both Langmuir-Hinshelwood(LH) and Eley-Rideal(ER) mechanisms are considered. The results show that the step of HCHO dissociative adsorption on Ti/Ti3C2O2 with activated O2 can release high energy of 4.05 e V based on the ER mechanism, which can help to overcome the energy barrier(1.04 e V) of the subsequent reaction steps. The charge transfer from *OH group to CO molecule(dissociated from HCHO) not only promotes *OH group activation but also plays an important role in the H2 O generation along the ER mechanism. Therefore, HCHO can be oxidized easily on Ti/Ti3C2O2 monolayer, this work could provide significant guidance to develop effective non-noble metal catalysts for HCHO oxidation and broaden the applications of MXene-based materials.

Hierarchical structured CoP nanosheets/carbon nanofibers bifunctional eletrocatalyst for high-efficient overall water splitting

The design of efficient,stable,and economical electrocatalysts for oxygen and hydrogen evolution reaction(OER and HER)is a major challenge for overall water splitting.Herein,a hierarchical structured CoP/carbon nanofibers(CNFs)composite was successfully synthesized and its potential application as a high-efficiency bifunctional electrocatalyst for overall splitting water was evaluated.The synergetic effect of two-dimensional(2D)CoP nanosheets and on e-dimensi on al(1D)CNFs endowed the CoP/CNFs composites with abundant active sites and rapid electron and mass transport pathways,and thereby significantly improved the electrocatalytic performances.The optimized CoP/CNFs delivered a current density of 10 mA cm^(-2) at low overpotential of 325 mV for OER and 225 mV for HER.In the overall water splitting,CoP/CNFs achieved a low potential of 1.65 V at 10 mA cm^(-2).The facile strategy provided in the present work can facilitate the design and development of multifunctional non-noble metal catalysts for energy applications.

A Low-Cost and Easily Prepared Manganese Carbonate as an Effi cient Catalyst for Aerobic Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran

A low-cost and easily prepared manganese carbonate(Mn CO_3) has been synthesized for catalytic conversion of 5-hydroxymethylfurfural(5-HMF) to 2,5-diformylfuran(DFF). The properties and morphology of the manganese carbonate were measured by SEM,XRD,TGA,BET and XPS. In this method,no harsh reaction conditions were required,and it was a simple and green process for the oxidation of 5-HMF into DFF. To achieve an optimum DFF yield,different reaction conditions,including reaction temperature,reaction time,catalyst amount,and solvents were investigated. Results from the experiments indicated that the highest DFF yield of 86.9% was obtained at 120 °C under atmospheric oxygen pressure after 6h. Finally,Mn CO_3 could be used at least five times with considerable stability.

Catalytic applications of single-atom metal-anchored hydroxides:Recent advances and perspective

Developing isolated single atomic noble metal catalysts is one of the most effective methods to maximize noble metal atom utilization efficiency and enhance catalytic performances.Layered double hydroxides(LDHs)are two-dimensional nanoarchitectures in which M^(3+) and M^(2+) sites are atomically isolated due to static repulsions,providing special anchoring sites for single noble metal atoms and enabling the tuning of catalytic activity.Herein,a comprehensive review of the advances in LDHs supported single-atom catalysts(M/LDH SACs)is presented,focusing on the synthetic strategies,structure characterization,and application of M/LDH SACs in energy devices.Strong electronic coupling between single atomic noble metal atoms and corresponding anchoring sites of LDHs determines not only the catalytic activity of M/LDH SACs but also the stability during catalytic reactions.Furthermore,a perspective is proposed to highlight the challenges and opportunities for understanding the reaction mechanism and development of highly efficient M/LDH SACs.

Mg-Al层状双金属氧化物催化臭氧降解阿特拉津的性能研究

采用水热沉淀-煅烧法在煅烧温度为400℃和Mg与Al物质的量比为3时制得Mg_(3)Al-400复合材料,通过SEM、FT-IR和XPS等分析Mg_(3)Al-400复合材料的形貌结构和理化组成,考察运行参数对其催化臭氧降解阿特拉津(ATZ)的影响。结果表明:Mg_(3)Al-400具有优异的催化臭氧降解ATZ性能,当其投加量为350 mg/L,ATZ质量浓度为5 mg/L,溶液初始pH值为6时,反应3 min后ATZ的去除率高达99%。此外,Mg_(3)Al-400在5次循环后仍具有较好的稳定性。自由基抑制试验表明·O_(2)-和·OH对ATZ的降解起到关键作用。对降解过程和反应机理分析可知,表面Mg—OH是其发挥催化作用的活性位点。

Correlative Mn-Co catalyst excels Pt in oxygen reduction reaction of quasi-solid-state zinc-air batteries

Zn-air batteries(ZABs)as a class of promising energy storage setups are generally powered by efficient and robust catalysts at the oxygen-involving cathode.Although the existing non-noble catalysts have outperformed noble Pt benchmark in the alkaline liquid-state ZABs,to the best of our knowledge few have excelled Pt in quasi-solid-state(QSS)ZABs.Herein,we found that an integrated Mn-Co cathode derived from the bimetallic Mn/Co metal organic frameworks generates a 1.4-fold greater power density in the QSS ZABs than a Pt cathode while its power density in liquid-state ZABs is only 0.8-fold of the latter.Moreover,such Mn-Co catalyst delivers high-rate oxygen reduction reaction(ORR)capability with half-wave potential of 0.84 V.The in-depth characterizations and analyses have demonstrated that the Co and Mn species show the specific affinity towards H_(2)O and O_(2),respectively,synergizing the ORR process in the water-deficient environment of QSS ZABs.This work has enlightened the rational design of non-noble metal catalysts to improve the power density of QSS ZABs.

Highly efficient and active Co-N-C catalysts for oxygen reduction and Zn-air batteries

In this study,the Lewis doping approach of polyaniline(PANI)was employed to fabricate cobait-nitrogen-carbon(Co-N-C)oxygen electrocatalysts for Zn-air batteries,aiming to enhance the active spots of Co-N-C.This resulting Co-N-C catalysts exhibited welldefined nanofiber networks,and the Brunauer-EmmettTeller(BET)analysis confirmed their substantial specific surface area.Electrochemical experiments demonstrated that the Co-N-C catalysts achieved the half-wave potential(vs.RHE)of 0.85 V in alkaline medium,overcoming Pt/C and iron-nitrogen-carbon(Fe-N-C)counterparts in extended cycle testing with only a 25 mV change in a half-wave potential after 5000 cycles.Remarkably,the highest power density measured in the zinc(Zn)-air battery reached 227 mW/cm^(2),a significant improvement over the performance of 101 mW/cm^(2) of the platinum on activated carbon(Pt/C)catalyst.These findings highlight the advantageous stability enhancement associated with the utilization of Co in the Co-N-C catalysts.

Metal-mediated Layer-by-layer Films of Multi-metalloporphyrin Arrays:a Novel Switchable Catalyst System

1 Results Metalloporphyrins as one kind of effective catalysts have received considerable attention in the past two decades,because of their selective oxidation of hydrocarbons and other organic compound under mild conditions.Great efforts have been made to oxidize or epoxidize the hydrocarbons and cycloparaffin with the oxidants such as PhIO,H2O2 catalyzed by the metalloporphyrins.However,the metalloporphyrins are normally dissolved in the reaction solution or immobilized on silica or other porous supp...