Strong synergy between physical and chemical properties:Insight into optimization of atomically dispersed oxygen reduction catalysts

Atomically dispersed catalysts exhibit significant influence on facilitating the sluggish oxygen reduction reaction(ORR)kinetics with high atom economy,owing to remarkable attributes including nearly 100%atomic utilization and exceptional catalytic functionality.Furthermore,accurately controlling atomic physical properties including spin,charge,orbital,and lattice degrees of atomically dispersed catalysts can realize the optimized chemical properties including maximum atom utilization efficiency,homogenous active centers,and satisfactory catalytic performance,but remains elusive.Here,through physical and chemical insight,we review and systematically summarize the strategies to optimize atomically dispersed ORR catalysts including adjusting the atomic coordination environment,adjacent electronic orbital and site density,and the choice of dual-atom sites.Then the emphasis is on the fundamental understanding of the correlation between the physical property and the catalytic behavior for atomically dispersed catalysts.Finally,an overview of the existing challenges and prospects to illustrate the current obstacles and potential opportunities for the advancement of atomically dispersed catalysts in the realm of electrocatalytic reactions is offered.

Ultra-small platinum nanoparticles segregated by nickle sites for efficient ORR and HER processes

In the electrochemical process,Pt nanoparticles(NPs)in Pt-based catalysts usually agglomerate due to Oswald ripening or lack of restraint,ultimately resulting in reduction of the active sites and catalytic efficiency.How to uniformly disperse and firmly fix Pt NPs on carbon matrix with suitable particle size for catalysis is still a big challenge.Herein,to prevent the agglomeration and shedding of Pt NPs,Ni species is introduced and are evenly dispersed in the surface of carbon matrix in the form of Ni-N-C active sites(Ni ZIF-NC).The Ni sites can be used to anchor Pt NPs,and then effectively limit the further growth and agglomeration of Pt NPs during the reaction process.Compared with commercial Pt/C catalyst,Pt@Ni ZIF-NC,with ultralow Pt loading(7 wt%)and ideal particle size(2.3 nm),not only increases the active center,but also promotes the catalysis kinetics,greatly improving the ORR and HER catalytic activity.Under acidic conditions,its half-wave potential(0.902 V)is superior to commercial Pt/C(0.861 V),and the mass activity(0.38 A per mg Pt)at 0.9 V is 4.7 times that of Pt/C(0.08 A per mg Pt).Besides,it also shows outstanding HER performance.At 20 and 30 mV,its mass activity is even 2 and 6 times that of Pt/C,respectively.Whether it is under ORR or HER conditions,it still shows excellent durability.These undoubtedly indicate the realization of dual-functional catalysts with low-Pt and high-efficiency properties.

Awakening the oxygen evolution activity of MoS_(2) by oxophilic-metal induced surface reorganization engineering

Although molybdenum disulfide (MoS_(2))-based materials are generally known as active electrocatalysts for the hydrogen evolution reaction (HER), the inert performance for the oxygen evolution reaction (OER) seriously limits their wide applications in alkaline electrolyzers due to there exists too strong metal-sulfur (M−S) bond in MoS_(2). Herein, by means of surface reorganization engineering of bimetal Al, Co-doped MoS_(2) (devoted as AlCo_(3)-MoS_(2)) through in situ substituting partial oxidation, we successfully significantly activate the OER activity of MoS_(2), which affords a considerably low overpotential of 323 mV at −30 mA cm^(−2), far lower than those of MoS_(2), Al-MoS_(2) and Co-MoS_(2) catalysts. Essentially, the AlCo_(3)-MoS_(2) substrate produces lots of M−O (M=Al, Co and Mo) species with oxygen vacancies, which trigger the surface self-reconstruction of pre-catalysts and simultaneously boost the electrocatalytic OER activity. Moreover, benefiting from the moderate M−O species formed on the surface, the redistribution of surface electron states is induced, thus optimizing the adsorption of OH* and OOH* intermediates on metal oxyhydroxides and awakening the OER activity of MoS_(2).

Thermodynamics fundamentals and energy efciency for the separation and high‑valued utilization of Fischer–Tropsch heavy oil

The development trend of Fischer–Tropsch(F–T)technology is to develop high value-added products.The separation of linearα-olefns with low cost is an efective method.Nevertheless,the lack of thermodynamic data and the huge energy consumption are the two main problems restricting the development of the separation process.The thermodynamic data of the key components(1-dodecene and n-dodecane)in the F–T product were measured.The Wilson binary interaction parameters of the key components were obtained.Next,one traditional distillation column sequence and two dividing wall column(DWC)sequences were designed to separate the F–T heavy oil to obtain narrow fractions with diferent carbon numbers.Then,the obtained fractions of C10 and C12 were simulated to obtain 1-decene and 1-dodecene,respectively.There was a traditional distillation and a diferential pressure thermal coupling distillation process.When separating 95.0%purity 1-decene and 1-octene,the direct DWC process and diferential pressure thermal coupled distillation are an excellent combination,which can reduce the energy by 33.1%(i.e.,11,286 kW)and total annual cost by 15.9%(i.e.,3.96×10^(6)$)compared with traditional distillation.

钌基单原子和团簇催化剂在电催化反应中的竞争和协同效应

单原子和团簇催化剂在电催化领域,尤其是可持续能源存储和转化领域的重要性,得到越来越多地认可.单原子催化剂具有低金属负载和高原子利用效率的优点,但由于其表面自由能常常使得单个原子不稳定而发生聚集.团簇催化剂则因为其高原子利用率以及多样的活性位点,能够克服单原子催化剂在中间体吸附和活化等方面的局限性.钌基催化剂在电催化中有着十分重要的应用前景.然而,准确设计钌基单原子和团簇催化剂的几何和电子结构,并揭示它们之间的结构-性质关系,仍然面临着巨大的挑战.因此,我们对钌基催化剂进行了分类和比较(同源/异源),重点总结了钌基单原子和团簇在电催化领域的竞争和协同效应.近年来,钌基催化剂在析氢反应(HER)方面取得了显著进展,因此着重介绍钌基催化剂在HER中的应用,并涵盖了其他电催化反应、双功能反应(HER/OER、HER/HOR)和电化学有机反应.此外,本文还探讨了钌基单原子和团簇在HER过程中的催化机理.最后,我们指出了在复杂钌基催化剂的工业应用开发策略中所面临的挑战和前景.

Engineering the Active Sites of MOF-derived Catalysts:From Oxygen Activation to Activate Metal-Air Batteries

The electrochemical processes of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)play a crucial role in various energy storage and conversion systems.However,the inherently slow kinetics of reversible oxygen reactions present an urgent demand for the development of efficient oxygen electrocatalysts.Recently,metal-organic framework(MOF)derivatives have attracted extensive attention in electrocatalysis research due to their unique porous structure,abundant active sites,and tunable structural properties.Especially,the optimization of the electronic structure of active sites in MOF derivatives has been proven as an effective strategy to enhance the catalytic activity.In this review,we provide an overview of the electronic structure optimization strategies for active sites in MOF derivatives as advanced catalysts in various O—O bond activation reactions,including the construction of synergistic effects between multiple sites,the development of heterogeneous interfaces,the utilization of metal support interactions,and the precise modulation of organic ligands surrounding catalytic active sites at the atomic level.Furthermore,this review offers theoretical insights into the oxygen activation and catalytic mechanisms of MOF derivatives,as well as the identification of active sites.Finally,the potential challenges and prospects of MOF derivatives in electrocatalysis are discussed.This review contributes to the understanding and advancement of efficient oxygen electrocatalysis in energy systems.

Molecular structure and application of covalent organic frameworks(COFs)in tumor therapy

The field of nanomedicine has emerged as a vital component in cancer treatment modalities over the past decades.Covalent organic frameworks(COFs)at the nanoscale have become a novel and promising category of biomaterials in the field of nanomedicine.Their distinctive properties,such as low density,exceptional porosity,crystalline structure,remarkable thermal stability,versatile functionality,and biocompatibility,contribute to their significant potential in cancer therapy applications.This review firstly discusses COFs with various morphologies in theranostic applications.The primary morphologies of COFs for tumors treatment can be categorized into four types:nanospheres,nanosheets,nano-rods/tubes and nanoparticles.Furthermore,we review recent research articles and systematically discuss recent advancements in COFs for chemotherapy,chemodynamic therapy,photodynamic therapy,photothermal therapy and combination therapy.In conclusion,we outline the current obstacles and potential future directions for this distinctive research area.

Advances in the study of HOR reaction mechanisms under alkaline conditions

Hydrogen energy is an important energy carrier,which is an ideal choice to meet energy demand and reduce harmful gas emissions.The green recycling of hydrogen energy depends on water electrolysis and hydrogen fuel cells,which involves hydrogen oxidation reaction(HOR)and hydrogen evolution reaction(HER).The activity of HER/HOR in alkaline electrolyte,however,exhibits a significantly lower magnitude(2–3 orders)compared to that observed in an acidic medium,which hinders the development of alkaline water electrolysis and alkaline membrane fuel cells.Therefore,comprehending the characteristics of HOR/HER activity in alkaline electrolytes and elucidating its underlyingmechanismis a prerequisite for the designof advanced electrocatalysts.Based on this background,this reviewwill briefly summarize the explanations and controversies about the basic HOR mechanism,including bifunctional mechanismand hydrogen binding energy theory.Moreover,the crucial affecting factors of theHOR kinetics,such as dband center theory,interfacial water recombination,alkali metal cations and electronic effects,are discussed.Thus,based on the above theories,the design principle,catalytic performance,and latest progress ofHOR electrocatalysts are summarized.An outlook and future research perspectives of advanced catalysts for hydrogen energy recycling are addressed.This reviewis helpful to understand the latest development ofHORmechanismand design cost-effective and high-performance HOR electrocatalysts towards the production of clean renewable energies.

Atomically dispersed dual Fe centers on nitrogen-doped bamboo-like carbon nanotubes for efficient oxygen reduction

Interfacial atomic configuration between dual-metal active species and nitrogen-carbon substrates is of great importance for improving the intrinsic activity of catalysts toward oxygen reduction reaction(ORR).Thus,from the atomic-scale engineering we develop a high intrinsic activity ORR catalyst in terms of incorporating atomically dispersed dual Fe centers(single Fe atoms and ultra-small Fe atomic clusters)into bamboo-like N-doped carbon nanotubes.Benefiting from atomically dispersed dual-Fe centers on the atomic interface of Fe-Nx/carbon nanotubes,the fabricated dual Fe centers catalyst exhibits an extremely high ORR activity(E_(onset)=1.006 V;E_(1/2)=0.90 V),beyond state-of-the-art Pt/C.Remarkably,this catalyst also shows a superior kinetic current density of 19.690 mA·cm^(−2),which is 7 times that of state-of-the-art Pt/C.Additionally,based on the excellent catalyst,the primary Zn-air battery reveals a high power density up to 137 mW·cm^(−2) and sufficient potential cycling stability(at least 25 h).Undoubtedly,given the unique structure–activity relationship of dual-Fe active species and metal-nitrogen-carbon substrates,the catalyst will show great prospects in highly efficient electrochemical energy conversion devices.

CeO2 quantum dots doped Ni-Co hydroxide nanosheets for ultrahigh energy density asymmetric supercapacitors

By integrating the merits of lanthanide elements and quantum dots,we firstly design CeO2 quantum dots doped Ni-Co hydroxide nanosheet via a controllable synthetic strategy,which exhibits a large specific capacitance(1370.7 F/g at 1.0 A/g) and a good cyclic stability(90.6% retention after 4000 cycles).Moreover,we assemble an aqueous asymmetric supercapacitor with the obtained material,which has an extremely high energy density(108.9 Wh/kg at 378 W/kg) and outstanding cycle stability(retaining88.1% capacitance at 2.0 A/g after 4000 cycles).

Tunable Atomic-Scale Steps and Cavities Break Both Stability and Activity Limits of CoO_(x) Nanosheets to Catalyze Oxygen Evolution

A highly active interface can enhance the catalytic efficiency of catalysts toward the oxygen evolution reaction(OER).However,accurately tuning their atomic interface configurations of defects with sufficient activity and stability remains a grand challenge.Herein,we report on breaking the activity and stability limits of CoO_(x) nanosheets in the OER process by constructing copious high-energy atomic steps and cavities,in which S or Ce atoms simultaneously replace O or Co atoms from CoO_(x),thus achieving high-energy atomic interface Ce,O-Co_(3)S_(4) nanosheets.By combining in situ characterization and density functional theory calculations,it is shown that the unique orbital coupling between Ce-4f,O(S)-2p,and Co-3d causes it to be closer to the Fermi level,leading to faster charge transfer capability.More importantly,the novel structure breaks the stability limit of cobalt sulfide with planar defects,which gives high catalytic activity and stability in 0.1 M KOH solutions,better than commercial RuO_(2) and IrO_(2) noble metal catalysts.As expected,Ce,O-Co_(3)S_(4) possesses much better turnover frequency activity(0.064 s^(-1))at an overpotential of 300 mV,which is ~7 times larger than that of Ce-CoO_(x)(0.009 s^(-1)).Our work presents a new perspective of designing catalysts with atomically dispersed orbital electronic coupling defects toward efficient OER electrocatalysis.