Activating Ru in the pyramidal sites of Ru_(2)P-type structures with earth-abundant transition metals for achieving extremely high HER activity while minimizing noble metal content

Rational design of efficient pH-universal hydrogen evolution reaction catalysts to enable large-scale hydrogen production via electrochemical water splitting is of great significance,yet a challenging task.Herein,Ru atoms in the Ru_(2)P structure were replaced with M=Co,Ni,or Mo to produce M_(2-x)Ru_(x)P nanocrystals.The metals show strong site preference,with Co and Ni occupying the tetrahedral sites and Ru the square pyramidal sites of the CoRuP and NiRuP Ru_(2)P-type structures.The presence of Co or Ni in the tetrahedral sites leads to charge redistribution for Ru and,according to density functional theory calculations,a significant increase in the Ru d-band centers.As a result,the intrinsic activity of CoRuP and NiRuP increases considerably compared to Ru_(2)P in both acidic and alkaline media.The effect is not observed for MoRuP,in which Mo prefers to occupy the pyramidal sites.In particular,CoRuP shows state-of-the-art activity,outperforming Ru_(2)P with Pt-like activity in 0.5 M H_(2)SO_(4)(η10=12.3 mV;η100=52 mV;turnover frequency(TOF)=4.7 s^(-1)).It remains extraordinarily active in alkaline conditions(η10=12.9 mV;η100=43.5 mV)with a TOF of 4.5 s^(-1),which is 4x higher than that of Ru_(2)P and 10x that of Pt/C.Further increase in the Co content does not lead to drastic loss of activity,especially in alkaline medium,where,for example,the TOF of Co_(1.9)Ru_(0.1)P remains comparable to that of Ru_(2)P and higher than that of Pt/C,highlighting the viability of the adopted approach to prepare cost-efficient catalysts.

Boosting Lean Electrolyte Lithium-Sulfur Battery Performance with Transition Metals: A Comprehensive Review

Lithium–sulfur(Li–S) batteries have received widespread attention, and lean electrolyte Li–S batteries have attracted additional interest because of their higher energy densities. This review systematically analyzes the effect of the electrolyte-to-sulfur(E/S) ratios on battery energy density and the challenges for sulfur reduction reactions(SRR) under lean electrolyte conditions. Accordingly, we review the use of various polar transition metal sulfur hosts as corresponding solutions to facilitate SRR kinetics at low E/S ratios(< 10 μL mg~(-1)), and the strengths and limitations of different transition metal compounds are presented and discussed from a fundamental perspective. Subsequently, three promising strategies for sulfur hosts that act as anchors and catalysts are proposed to boost lean electrolyte Li–S battery performance. Finally, an outlook is provided to guide future research on high energy density Li–S batteries.

Highly dispersed V_2O_5/TiO_2 modified with transition metals(Cu,Fe,Mn,Co) as efficient catalysts for the selective reduction of NO with NH_3

Different transition metals were used to modify V2O5-based catalysts （M-V, M = Cu, Fe, Mn, Co） on TiO2 via impregnation, for the selective reduction of NO with NH3. The introduced metals induced high dispersion in the vanadium species and the formation of vanadates on the TiO2 support, and increased the amount of surface acid sites and the strength of these acids. The strong acid sites might be responsible for the high N2 selectivity at higher temperatures. Among these catalysts, Cu-V/TiO2 showed the highest activity and N2 selectivity at 225-375 ~C. The results of X-ray photo- electron spectroscopy, NH3-temperature-programmed desorption, and in-situ diffuse reflectance infrared Fourier transform spectroscopy suggested that the improved performance was probably due to more active surface oxygen species and increased strong surface acid sites. The outstanding activity, stability, and SO2/H2O durability of Cu-V/TiO2 make it a candidate to be a NOx removal catalyst for stationary flue gas.

Use of Solid State Carbothermic Reduction in Production of Transition Metals and Their Carbides

The use of solid state carbothermic reduction as a precursor to the smelting of transition metal ores was examined . The advantages of the introduction of a prereduction stage include enabling the more efficient use of fines and the achievement of higher energy efficiencies. A solid state reduction using carbon as the reductant offers a simpler alternative for their treatment. Subsequent treatment of the reduced material could include intensive bath smelting to produce ferroalloys or, in some case, solid state separation of the transition metal carbide where this has commercial significance.

Doping effects of transition metals on the superconductivity of (Li,Fe)OHFeSe films

The doping effects of transition metals(TMs = Mn, Co, Ni, and Cu) on the superconducting critical parameters are investigated in the films of iron selenide(Li,Fe)OHFe Se. The samples are grown via a matrix-assisted hydrothermal epitaxy method. Among the TMs, the elements of Mn and Co adjacent to Fe are observed to be incorporated into the crystal lattice more easily. It is suggested that the doped TMs mainly occupy the iron sites of the intercalated(Li,Fe)OH layers rather than those of the superconducting Fe Se layers. We find that the critical current density J_(c) can be enhanced much more strongly by the Mn dopant than the other TMs, while the critical temperature T_(c) is weakly affected by the TM doping.

Influence of transition metals(Sc,Ti,V,Cr,and Mn)doping on magnetism of CdS

The influence of transition metals(Sc,Ti,V,Cr,and Mn)doping at different distances on the magnetism of CdS is studied by using generalized gradient approximation combined with Hubbard U in the VASP package.The results show that the doping systems are more stable,easy to form,and the wurtzite structure of CdS is not changed.It is found that the systems are antiferromagnetic(AFM)when nearest neighbor doping,which is attributed to the direct charge transfers between two impurity ions.The systems are ferromagnetic(FM)when the doping distance increases further,since the double exchange interactions are observed among the 3d orbital of the transition metal,the Cd-5s and the S-3p orbitals are at conduction band minimum.We also found that the total magnetic moment of each ferromagnetic system increases with the order of SC to Mn-doping,the spin polarizability of Cr-doping system is 100%.The estimated Curie temperature indicates that the Cr-and Mn-doped CdS in this paper can achieve room-temperature ferromagnetic characteristics,especially the Cr doping is the most prominent.And TM-doping does not destroy the semiconductor characteristics of the system.Therefore,the TM-doped CdS can be used as an ideal dilute magnetic semiconductor functional material.

Determination of the Deep Levels of Transition Metals in n-Type Silicon by Using DLTS Method

Since the correspondence between the impurity and its energy levels within the bands is not exactly known, it is difficult to assign the impurity according to its levels. In this work, several metallic impurities were intentionally doped into samples, then their energy levels were determined by DLTS.

Electron Donating Property and Catalytic Activity ofPerovskite-type Mixed Oxides (ABO_3) Consisting of Rare Earth and 3d Transition Metals

The catalytic activity of Perovskite-type mixed oxides (LaCoO3, PrCoO3 and SmCoO3) for the reduction of cyclohexanone to cyclohexanol with 2-propanol (Meerwein-PonndorfVerley reduction) has been studied. The data have been correlated with the surface electron donor properties of these mixed oxides

Screening-Dependent Study of Superconductivity in 3d-Transition Metals Binary Alloys Superconductors

In the present article, we report the screening-dependent study of the superconducting state parameters （SSPs）, viz. electron-phonon coupling strength A, Coulomb pseudopotential μ^＊, transition temperature TC, isotope effect exponent a, and effective interaction strength No V of 3d-band transition metals binary alloys superconductors have been made extensively in the present work using a model potential formalism and employing the pseudo-alloy-atom （PAA） model for the first time. Five local field correction functions proposed by Hartree （H）, Taylor （T）, Ichimaru-Utsumi （IU）, Farid et al. （F） and Sarkar et al. （S） are used in the present investigation to study the screening influence on the aforesaid properties. The present results of the SSPs obtained from H-screening are found in qualitative agreement with the available experimental data wherever exist.

Molecular Simulation Study on Interaction of Thiophene Sulfides with Transition Metals

The computer molecular simulation technique was applied to study the chemisorption of thiophene and tetramethylthiophene as the model sulfides on the simple oxides and complex oxides of some transition metals as the catalytic materials. The study disclosed that the thiophene sulfides could enter into chemisorption with metal oxides such as VO, ZnO, NiO and Zn-Al-spinel. This interaction could lead to thiophene molecular structure deformation to be in an activated adsorption state, which could help to promote the conversion of thiophene sulfides in the course of catalytic cracking. The VO with a valence of 2 could provide relatively strong selective adsorption sites for the conversion of thiophene sulfides to apparently transform the molecular structures and electron cloud states of such heterocyclic sulfur compounds such as thiophene and tetramethylthiophene into an activated adsorption state. The effect of this interaction was more pronounced with respect to tetramethylthiophene.

ELECTRONIC STATES AND HYDROGEN EMBRITTLEMENTIN TRANSITION METALS

An electronic approach to the mechanism of hydrogen embrittlement in metals is pre-sented and discussed. Some problems of the mechanism of hydrogen embrittlement are pointed out from an electronic point of view. Electronic structure calculations in a periodically cleaved or slipped lattice are developed in orker to identofy deformation-sensitive electronic states in the absence of hydrogen. The calculational results are given and discussed for a trunsition metal, Pd. Electronic structure calculations in the presence of hydrogen are outlined and hydrogen embrittlement in transition metals is discussed in terms of electronic states.

Synthesis, Characterization and Biological Activity of Transition Metals with Schiff Base Derived from Adamantaneamineand o-Vanillin

Five new solid complexes were synthesized about transition metals with Schiff base（ L, C18H23NO2 ） derived from adamantaneamine and o-vanillin, and characterized by elemental analysis, molar conductance, infrared spectra, UV-vis spectra, thermal analysis. Their chemical formula are [ML2]（ClO4）2 （ M= Mn, Co, Ni, Cu, Zn）, and the coordination numbers are four, The antibacterial activity of Schiff base ligand and its complexes was studied.

A Fundamental DFT Study of Anatase(TiO2) Doped with 3d Transition Metals for High Photocatalytic Activities

Anatase（TiO_2） has been widely used in photocatalysis. However, it can only absorb near-ultraviolet light with a wavelength below approximately 388 nm due to a wide band gap. Therefore a modification should be made for anatase to increase its capability in utilizing more abundant visible light. We investigated the doped anatase with the most promising 3d transition metal elements, and the results showed that the visible light absorption intensity was increased significantly due to the reduced band gap and the cavitation effects. As compared to other 3d transition metals, Cu was found to be the most effective one in improving anatase photocatalytic effects. In addition, greater Cu concentration doped in the anatase increased the photocatalysis effects but reduced the anatase stability, therefore, an optimized Cu concentration should be considered to optimize the anatase photocatalysis activity.

Multiple transition metals modulated hierarchical networks for high performance of metal-ion batteries

Searching anodes with excellent electrochemical performance has been in great demand for rechargeable metal ion batteries. In this contribution, Fe/Co co-doped Ni S with N-based carbon(Fe Co-NiS@NC) derived from trimetallic Prussian blue analogue is designed and synthesized. The composition can be easily adjusted and modulated by multi-metals. In addition, the well-designed carbon nanocubes effectively promote electronic conductivity and buffer the volume change upon charge and discharge cycling, resulting in good capacity and long-term cycle life for both lithium-ion batteries and sodium-ion batteries, with capacities of 1018 m Ah g^(-1)(vs. Li/Li^(+)) and 454 m Ah g^(-1)(vs. Na/Na^(+)), respectively, after 100 cycles.Kinetics studies indicate that the electrochemical behaviors are manipulated by both diffusion and pseudocapacitance processes. These strategies would open new opportunities and potention for novel energy storage.

Effect of Transition Metals on Catalytic Performance of Ru/Sepiolite Catalyst for Methanation of Carbon Dioxide

The effects of Mo, Mn and Zr transitional metals on the catalytic performance of Ru/sepiolite for CO2 methanation were investigated. The results indicated that addition of the transitional metals affected the activity of the Ru/sepiolite remarkably, and the activities of the catalysts were closely associated with the electronic state of the ruthenium surface. The addition of Mo increased the active surface area, the Ru dispersity, the number of active sites, and the resistance to poisoning. According to the Transition State Theory, when Mo is added into the Ru/sepiolite catalyst, the decrease in surface energy is at a cost of an increment in steric hindrance. When T≤674 K, the energy factor was dominating, and resulted in a decreasing in the ratio of S(CU4)/S(CO). Otherwise, the steric factor dominated the reaction course.

Transition metals for stabilizing lithium metal anode:advances and perspectives

As the capacity of lithium-ion batteries gradually reaches its limit,the high-capacity characteristics of lithium metal batteries(LMBs)make them one of the most promising electrochemical energy storage devices currently.However,uncontrolled lithium dendrite growth can cause poor cell performance and severe safety issues,seriously slowing down the commercialization of LMBs.Transition metals(TMs)are lithiophilic materials that effectively stabilize lithium metal anode(LMA)and inhibit dendrite growth.Herein,the growth of lithium dendrites and the performance of TMs in stabilizing lithium metals are comprehensively discussed in this review.First,we elucidated the formation mechanisms of lithium dendrite,and we put forward several strategies to suppress lithium dendrite formation based on the understanding of these mechanisms.Then,the application of TMs and their compounds to stabilize LMA and their corresponding mechanisms are comprehensively clarified.Last,further research perspectives of TMs in stabilizing LMA are emphasized in detail.

Ligand effect in surface atomic sites of group VI B transition metals on ultrathin Pt nanowires for enhanced oxygen reduction

Increasing the utilization efficiency of platinum is critical for advancing proton exchange-membrane fuel cells(PEMFCs).Despite extensive research on catalysts for the cathodic oxygen reduction reaction(ORR),developing highly active and durable Pt-based catalysts that can suppress surface dealloying in corrosive acid conditions remains challenging.Herein,we report a facile synthesis of bimetallic ultrathin PtM(M=Mo,W,and Cr)nanowires(NWs)composed of group VI B transition metal atomic sites anchored on the surface.These NWs possess uniform sizes and well-controlled atomic arrangements.Compared to PtW and PtCr catalysts,the PtMo0.05 NWs exhibit the highest half-wave potential of 0.935 V and a mass activity of 1.43 A·mgPt^(−1).Remarkably,they demonstrate a remarkable 23.8-fold enhancement in mass activity compared to commercial Pt/C for ORR,surpassing previously reported Pt-based catalysts.Additionally,the PtMo NWs cathode in membrane electrode assembly tests achieves a remarkable peak power density of 1.443 W·cm^(−2)(H_(2)-O_(2)conditions at 80℃),which is 1.09 times that of commercial Pt/C.The ligand effect in the bimetallic surface not only facilitates strong coupling between Mo(4d)and Pt(5d)atomic orbitals to hinder atom leaching but also modulates the d-states of active site,significantly optimizing the adsorption of key oxygen(*O and*OH)species and accelerating the rate-determining step in ORR pathways.

Insights into reactive oxygen species formation induced by water-soluble organic compounds and transition metals using spectroscopic method

Ambient particulate matter(PM)can cause adverse health effects via their ability to produce Reactive Oxygen Species(ROS).Water-Soluble Organic Compounds(WSOCs),a complex mixture of organic compounds which usually coexist with Transition Metals(TMs)in PM,have been found to contribute to ROS formation.However,the interaction between WSOCs and TMs and its effect on ROS generation are still unknown.In this study,we examined the ROS concentrations of V,Zn,Suwannee River Fulvic Acid(SRFA),Suwannee River Humic Acid(SRHA)and the mixtures of V/Zn and SRFA/SRHA by using a cell-free 2’,7’-Dichlorodihydrofluorescein(DCFH)assay.The results showed that V or Zn synergistically promoted ROS generated by SRFA,but had an antagonistic effect on ROS generated by SRHA.Fluorescence quenching experiments indicated that V and Zn were more prone to form stable complexes with aromatic humic acid-like component(C1)and fulvic acidlike component(C3)in SRFA and SRHA.Results suggested that the underlying mechanism involving the fulvic acid-like component in SRFA more tending to complex with TMs to facilitate ROS generation throughπelectron transfer.Our work showed that the complexing ability and complexing stability of atmospheric PM organics with metals could significantly affect ROS generation.It is recommended that the research deploying multiple analytical methods to quantify the impact of PM components on public health and environment is needed in the future.

Mass-Based Environmental Factor and Energy Assessment of Microwave-Assisted Synthesized Transition Metal Nanostructures

This paper describes mass-based energy phase-space projection of microwave-assisted synthesis of transition metals (zinc oxide, palladium, silver, platinum, and gold) nanostructures. The projection uses process energy budget (measured in kJ) on the horizontal axes and process density (measured in kJg−1) on the vertical axes. These two axes allow both mass usage efficiency (Environmental-Factor) and energy efficiency to be evaluated for a range of microwave applicator and metal synthesis. The metrics are allied to the: second, sixth and eleventh principle of the twelve principle of Green Chemistry. This analytical approach to microwave synthesis (widely considered as a useful Green Chemistry energy source) allows a quantified dynamic environmental quotient to be given to renewable plant-based biomass associated with the reduction of the metal precursors. Thus allowing a degree of quantification of claimed “eco-friendly” and “sustainable” synthesis with regard to waste production and energy usage.

Templated synthesis of transition metal phosphide electrocatalysts for oxygen and hydrogen evolution reactions

Transition metal phosphides(TMPs)have been regarded as alternative hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts owing to their comparable activity to those of noble metal-based catalysts.TMPs have been produced in various morphologies,including hollow and porous nanostructures,which are features deemed desirable for electrocatalytic materials.Templated synthesis routes are often responsible for such morphologies.This paper reviews the latest advances and existing challenges in the synthesis of TMP-based OER and HER catalysts through templated methods.A comprehensive review of the structure-property-performance of TMP-based HER and OER catalysts prepared using different templates is presented.The discussion proceeds according to application,first by HER and further divided among the types of templates used-from hard templates,sacrificial templates,and soft templates to the emerging dynamic hydrogen bubble template.OER catalysts are then reviewed and grouped according to their morphology.Finally,prospective research directions for the synthesis of hollow and porous TMP-based catalysts,such as improvements on both activity and stability of TMPs,design of environmentally benign templates and processes,and analysis of the reaction mechanism through advanced material characterization techniques and theoretical calculations,are suggested.