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.

Atomically Dispersed Zinc Active Sites Efficiently Promote the Electrochemical Conversion of N_(2) to NH_(3)

At present,the research on highly active and stable nitrogen reduction reaction catalysts is still challenging work for the electrosynthesis of ammonia(NH_(3)).Herein,we synthesized atomically dispersed zinc active sites supported on N-doped carbon nanosheets(Zn/NC NSs)as an efficient nitrogen reduction reaction catalyst,which achieves a high ammonia yield of 46.62μg h^(-1)mg^(-1)_(cat).at-0.85 V(vs RHE)and Faradaic efficiency of 95.8%at-0.70 V(vs RHE).In addition,Zn/NC NSs present great stability and selectivity,and there is no significant change in NH_(3)rate and Faradaic efficiencies after multiple cycles.The structural characterization shows that the active center in the nitrogen reduction reaction process is the Zn-N_(4)sites in the catalyst.DFT calculation confirms that Zn/NC with Zn-N_(4)configuration has a lower energy barrier for the formation of^(*)NNH intermediate compared with pure N-doped carbon nanosheets(N-C NSs),thus promoting the hydrogenation kinetics in the whole nitrogen reduction reaction process.

High‑Quality Epitaxial N Doped Graphene on SiC with Tunable Interfacial Interactions via Electron/Ion Bridges for Stable Lithium‑Ion Storage

Tailoring the interfacial interaction in SiCbased anode materials is crucial to the accomplishment of higher energy capacities and longer cycle lives for lithium-ion storage.In this paper,atomic-scale tunable interfacial interaction is achieved by epitaxial growth of high-quality N doped graphene(NG)on SiC(NG@SiC).This well-designed NG@SiC heterojunction demonstrates an intrinsic electric field with intensive interfacial interaction,making it an ideal prototype to thoroughly understand the configurations of electron/ion bridges and the mechanisms of interatomic electron migration.Both density functional theory(DFT)analysis and electrochemical kinetic analysis reveal that these intriguing electron/ion bridges can control and tailor the interfacial interaction via the interfacial coupled chemical bonds,enhancing the interfacial charge transfer kinetics and preventing pulverization/aggregation.As a proof-of-concept study,this well-designed NG@SiC anode shows good reversible capacity(1197.5 mAh g^(−1)after 200 cycles at 0.1 A g^(−1))and cycling durability with 76.6%capacity retention at 447.8 mAh g^(−1)after 1000 cycles at 10.0 A g^(−1).As expected,the lithium-ion full cell(LiFePO_(4)/C//NG@SiC)shows superior rate capability and cycling stability.This interfacial interaction tailoring strategy via epitaxial growth method provides new opportunities for traditional SiC-based anodes to achieve high-performance lithium-ion storage and beyond.

Superior oxygen electrocatalyst derived from metal organic coordination polymers by instantaneous nucleation and epitaxial growth for rechargeable Li-O_(2) battery

Rechargeable aprotic Li-O_(2)batteries have attractea increasing attention due to their extremely high capacity,and it is very important to design appropriate strategies to synthesize efficient catalysts used as oxygen cathode.In present work,we present an expedient "instantaneous nucleation and epitaxial growth"(INEG) synthesis strategy for convenient and large-scale synthesis of ultrafine MOCPs nanoparticles(size 50-100 nm) with obvious advantages such as fast synthesis,high yields,low costs and reduced synthetic steps.The bimetallic Ru/Co-MOCPs are further pyrolyzed to obtain bimetallic Coand low content of Ru-based nanoparticles embedded within nitrogen-doped carbon(Ru/Co@N-C) as an efficient catalyst used in Li-O_(2)battery.The Ru/Co@N-C provides porous carbon framework for the ion transportation and O_(2)diffusion,and has large amounts of metal/nonmetal sites as active site to promote the oxygen reduction reaction(ORR)/oxygen evolution reaction(OER) in Li-O_(2)batteries.As a consequence,a high discharge specific capacity of 15246 mA h g^(-1)at 250 mA g^(-1), excellent rate capability at different current densities,and stable overpotential during cycling,are achieved.This work opened up a new understanding for the industrialized synthesis of ultrafine catalysts for Li-O_(2)batteries with excellent structural characteristics and electrochemical performance.

Surface hydrophobic modification of MXene to promote the electrochemical conversion of N_(2) to NH_(3)

Hydrophobic treatment of the catalyst surfaces can suppress the competitive hydrogen evolution reaction(HER) during the nitrogen reduction reaction(NRR).In this work,the surface of Ti_(3)C_(2)Ti_(x) MXene is modified by cetyltrimethylammonium bromide(CTAB) and trimethoxy(3,3,4,4,5,5,6,6,7,7,8,8,8-trideca fluorooctyl) silane(FOTS) to increase the hydrophobicity of MXenes.The ammonia(NH_(3)) production rate and faradaic efficiency(FE) are improved from 37.62 to 54.01 μg h^(-1)mg_(cat)^(-1).and 5.5% to 18.1% at-0.7 V vs.RHE,respectively after surface modification.^(15)N isotopic labeling experiment confirms that nitrogen in produced ammonia originates from N_(2) in the electrolyte.The excellent NRR activity of surface hydrophobic MXenes is mainly due to surfactant molecules,which inhibit the entry of water molecules and the competitive HER,which have been verified by in situ FT-IR,DFT and molecular dynamics calculations.This strategy provides an ingenious method to design more active NRR electrocatalysts.

基于癸二酸二异辛酯的环保型复合缓蚀剂对钢筋的缓蚀效应

应用缓蚀剂控制混凝土中钢筋的腐蚀具有高效、廉价和易操作等优点,越来越受腐蚀研究者的关注。近年来,对环保型缓蚀剂的需求日益增加。因此,本工作发展了由癸二酸二异辛酯、D-葡萄糖酸钠和硫酸锌组成的环保型复合缓蚀剂并应用电化学测试技术和表面分析方法研究其对钢筋的缓蚀作用。结果表明,Q235钢筋在pH为11.00,含0.5 mol·L^(−1) NaCl的模拟污染的混凝土孔隙液中处于活化状态并发生局部腐蚀。含有59 mmol·L^(−1)癸二酸二异辛酯,0.5 mmol·L^(−1) D葡萄糖酸钠和1.5 mmol·L^(−1)硫酸锌组成的复合缓蚀剂对钢筋具有良好的协同缓蚀效应,在模拟污染混凝土孔隙液中和水泥砂浆试样中对钢筋的缓蚀效率分别达到96.8%和90.0%。该复合缓蚀剂是一种混合型缓蚀剂,对钢筋腐蚀的阴极反应和阳极反应均有抑制作用。

Performance improvement of ultra-low Pt proton exchange membrane fuel cell by catalyst layer structure optimization

Reducing the loading of noble Pt-based catalyst is vital for the commercialization of proton exchange membrane fuel cell(PEMFC),However,severe mass transfer polarization loss resulting in fuel cell performance decline will be encountered in ultra-low Pt PEMFC.In this work,mild oxidized multiwalled carbon nanotubes(mMWCNT)were adopted to construct the catalyst layer,and by varying the loading of carbon nanotubes,the catalyst layer structure was optimized.A high peak power density of 1.23 W·cm^(-2) for the MEA with mMWCNT was obtained at an ultra-low loading of 120μg·cm^(-2) Pt/PtRu(both cathode and anode),which was 44.7%higher than that of MEA without mMWCNT.Better catalyst dispersion,low charge transfer resistance,more porous structure and high hydrophobicity of catalyst layer were ascribed for the reasons of the performance improvement.

Interatomic diffusion in Pd-Pt core-shell nanoparticles

Pt monolayer-based core-shell catalysts have garnered significant interest for the application of low temperature fuel cell technology as their use may enable a decreased loading of Pt while still providing sufficient current density to meet volumetric requirements. One promising candidate in this class of materials is a Pd@Pt core-shell catalyst, which shows enhanced activity toward oxygen reduction reaction(ORR). One concern with the use of Pd@Pt, however, is the durability of the core-shell structure as Pd atoms are thermodynamically favored to migrate to the surface. The pathway of the migration has not been systematically studied. The current study explores the stability of this structure to thermal annealing and probes the effect of this heat treatment on the catalyst surface structure and its oxygen reduction activity. It was found that surface alloying between Pd and Pt occurs at temperatures as low as 200 °C, and significantly alters the structure and ORR catalytic activity in the range of 200–300 °C. Our results shed lights on the thermal induced interatomic diffusion in all core-shell and thin film structures.

Metal organic framework‐ionic liquid hybrid catalysts for the selective electrochemical reduction of CO_(2) to CH4

The electrochemical reduction of CO_(2) towards hydrocarbons is a promising technology that can utilize CO_(2) and prevent its atmospheric accumulation while simultaneously storing renewable en‐ergy.However,current CO_(2) electrolyzers remain impractical on a large scale due to the low current densities and faradaic efficiencies(FE)on various electrocatalysts.In this study,hybrid HKUST‐1 metal‐organic framework‒fluorinated imidazolium‐based room temperature ionic liquid(RTIL)electrocatalysts are designed to selectively reduce CO_(2) to CH_(4).An impressive FE of 65.5%towards CH_(4) at-1.13 V is achieved for the HKUST‐1/[BMIM][PF_(6)]hybrid,with a stable FE greater than 50%maintained for at least 9 h in an H‐cell.The observed improvements are attributed to the increased local CO_(2) concentration and the improved CO_(2)‐to‐CH_(4) thermodynamics in the presence of the RTIL molecules adsorbed on the HKUST‐1‐derived Cu clusters.These findings offer a novel approach of immobilizing RTIL co‐catalysts within porous frameworks for CO_(2) electroreduction applications.

Heterostructuring 2D TiO_(2) nanosheets in situ grown on Ti_(3)C_(2)T_(x) MXene to improve the electrocatalytic nitrogen reduction

In this study,TiO_(2) nanosheets(NSs)grown in situ on extremely conductive Ti_(3)C_(2)T_(x) MXene to form TiO_(2)/Ti_(3)C_(2)T_(x) MXene composites with abundant active sites are proposed to effectively achieve elec‐trocatalytic NH_(3) synthesis.Electron transfer can be promoted by Ti_(3)C_(2)T_(x) MXene with high conduc‐tivity.Meanwhile,the TiO_(2) NSs in‐situ formation can not only avoid Ti_(3)C_(2)T_(x) MXene microstacking but also enhance the surface specific area of Ti_(3)C_(2)T_(x) MXene.The TiO_(2)/Ti_(3)C_(2)T_(x) MXene catalyst reach‐es a high Faradaic efϐiciency(FE)of 44.68%at−0.75 V vs.RHE and a large NH3 yield of 44.17µg h^(-1) mg^(-1)cat.at−0.95 V,with strong electrochemical durability.15N isotopic labeling experiments imply that the N in the produced NH3 originated from the N2 of the electrolyte.DFT calculations were conducted to determine the possible NRR reaction pathways for TiO_(2)/Ti_(3)C_(2)T_(x) MXene composites.MXene catalysts combined with other materials have been rationally designed for efficient ammonia production under ambient conditions。

Insight into the boosted activity of TiO2–CoP composites for hydrogen evolution reaction:Accelerated mass transfer,optimized interfacial water,and promoted intrinsic activity

The use of abundant elements in the earth as electrocatalytic hydrogen production catalysts is of great significance for hydrogen energy cycling.Herein,we report amorphous TiO_(2)-decorated CoP/NF(TiO_(2)–CoP/NF)as an excellent electrocatalyst for alkaline hydrogen evolution reaction(HER).The welldispersed amorphous TiO_(2)on nanoneedle-like CoP arrays preserves the crystal structure of CoP and changes its electronic structure by interfacial charge transfer.Compared to CoP/NF catalyst,the Ti O_(2)–CoP/NF composite catalyst exhibits high HER activity with an overpotential of 61 mV at 10 mA cm^(-2)and high stability.Importantly,it almost maintains the Volmer step as a rate-determining step(RDS)and the Tafel slope at a wide cathodic potential range showing the fast kinetics under large polarization regions.Theoretical simulations reveal that the combination of TiO_(2)and CoP selectively accelerates the hydrated K+diffusion,regulates the interfacial water orientation to adapt to the subsequent smooth water dissociation,and optimizes*H adsorption/H_(2)desorption.The strengthened coupling of HER multi-scale-processes on transition metal compound composites catalysts is the underlying mechanism for improving HER activity.

Preface to Special Column on Electrocatalysis

Energy is the most important problem that we are facing.The limited fossil fuel reserves and the air pollution caused by the consuming of fossil fuels force the governments,industries and academia to look for renewable energies and their conversion-storage devices.Some novel concepts based on the electrochemical reactions have been considered as promising solutions to help solve energy problems and improve the quality of our lives.Electrocatalysis plays a critical role in the advanced electrochemical energy systems such as fuell cells,metal-air batteries,and electrolyzers.

海胆状CoTe-CoP异质结构催化剂在全pH范围内高效析氢

研发长效稳定、pH适应性强的析氢反应(HER)催化剂对实现大规模制氢具有重要意义.界面工程是研发高效HER催化剂的有效策略之一.本文成功构建了海胆状异质结构催化剂CoTe-CoP/NF.CoTe和CoP的协同作用不仅优化了电子结构、暴露了更多的活性位点,而且有效地提高了催化剂的亲水性和疏气性.密度泛函理论计算表明:CoTe与CoP之间的相互作用有效地降低了水的解离能垒,同时增强了对H~*的吸附.这些结果使得CoTe-CoP/NF在整个pH范围内具有优异的HER性能和催化稳定性.在酸性、碱性和中性介质中,CoTe-CoP/NF电极驱动10 mA cm^(-2)的电流密度仅需51、53和75 mV的过电位.总之,本工作为在全pH范围内构建高性能HER催化剂提供了一种界面工程新策略.

Toward carbon neutrality by artificial photosynthesis

CO_(2)is not only the primary cause of climate change but also an abundant and recyclable carbon resource.The breakthrough in emerging disruptive technologies such as carbon capture and storage(CCS),power-to-X,and direct air capture(DAC)is fundamental to achieving carbon neutrality.Among these technologies,artificial photosynthesis offers an attractive method for recycling carbon dioxide and water into fuels and chemicals using solar energy(CO_(2)+H_(2)O+sunlight→fuels+chemicals).It holds great promise for addressing the critical challenges associated with elevated CO_(2)concentrations and securing a sustainable supply of fuels and chemicals for economic sectors.

Highly active and durable core-shell electrocatalysts for proton exchange membrane fuel cells

This work presents simple post-treatment methods to selectively and partially remove the Pd core of Pd-Pt core–shell(Pt@Pd/C)catalysts.The proton exchange membrane fuel cell with the post-treated Pt@Pd/C cathode(Pt loading:0.10 mg·cm^(-2))delivers an impressive peak power density of 1.2 W·cm^(-2).The partial removal of Pd core endows an ultrahigh oxygen reduction reaction(ORR)mass activity of 0.32 A·g_(PGM)-1 when normalized to the platinum group metal(PGM)mass,or equivalently 0.55 A·mg_(Pt)^(-1) at 0.9 V measured in a fuel cell.The post-treatment thickens the Pt shells and mitigates the Pd dissolution during potential cycling.As a result,the post-treated core-shell catalyst demonstrates superior durability in ORR mass activity and polarization power density retention than untreated core-shell catalyst and benchmark Pt/C.In-situ inductively coupled plasmamass spectrometry(ICP-MS)results highlight that the amount of dissolved Pd in post-treated core–shell catalyst is 17-times lower than that of the untreated one.Our findings highlight the importance of structural tuning of catalysts in enhancing their mass activity and durability.

Development of organic redox-active materials in aqueous flow batteries: Current strategies and future perspectives

Aqueous redox flow batteries,by using redox-active molecules dissolved in nonflammable water solutions as electrolytes,are a promising technology for grid-scale energy storage.Organic redox-active materials offer a new opportunity for the construction of advanced flow batteries due to their advantages of potentially low cost,extensive structural diversity,tunable electrochemical properties,and high natural abundance.In this review,we present the emergence and development of organic redox-active materials for aqueous organic redox flow batteries(AORFBs),in particular,molecular engineering concepts and strategies of organic redox-active molecules.The typical design strategies based on organic redox species for high-capacity,high-stability,and high-voltage AORFBs are outlined and discussed.Molecular engineering of organic redox-active molecules for high aqueous solubility,high chemical/electrochemical stability,and multiple electron numbers as well as satisfactory redox potential gap between the redox pair is essential to realizing high-performance AORFBs.Beyond molecular engineering,the redoxtargeting strategy is an effective way to obtain high-capacity AORFBs.We further discuss and analyze the redox reaction mechanisms of organic redox species based on a series of electrochemical and spectroscopic approaches,and succinctly summarize the capacity degradation mechanisms of AORFBs.Furthermore,the current challenges,opportunities,and future directions of organic redox-active materials for AORFBs are presented in detail.

Investigation of cubic Pt alloys for ammonia oxidation reaction

As a promising fuel candidate,ammonia has been successtully used as anode feed in alkaline fuel cells.However,current technology in catalysts for ammonia electro-oxidation reaction(AOR)with respect to both cost and performance is inadequate to ensure large scale commercial application of direct ammonia fuel cells.Recent studies found that alloying Pt with different transition metals and controlling the morphology of catalysts can improve the AOR activity,and thus potentially can solve the cost issue.Herein,(100)-terminated Pt-M nanocubes(M=3d-transition metals Fe,Co,Ni,Zn)are synthesized via wet-chemistry method and their catalytic activities toward AOR are evaluated.The addition of Fe,Co,Ni and Zn elements can enhance the AOR activity due to decrease in oxophilicity of platinum and bifunctional mechanism.Pt-Zn exhibits the maximum mass activity and specific ativity with values of 0.41 A/mgpt and 169 mA/cm2 that are 1.6 and 1.8 times higher than Pt nanocubes,respectively.Pt-Fe,Pt-Co and PI-Ni nanocubes also ilustrate higher mass and specific activities compared to Pt nanocubes.

Direct synthesis of L10-FePt nanopartides from single-source bimetallic complex and their electrocatalytic applications in oxygen reduction and hydrogen evolution reactions

L10-FePt nan oparticles(NPs)with high chemical ordering represent effective electrocatalysts to reduce the cost and enhance theircatalytic performanee in fuel cells.A molecular strategy of preparing highly ordered FePt NPs was used by direct pyrolysis of a Fe,Pt-containing bimetallic complex.The resultant L10-FePt NPs had very high crystallinity as reflected by the obvious diffractionpatterns,clear lattice fringes and characteristic X-ray diffraction peaks,etc.Besides,the strong ferromagnetism with room temperaturecoercivity of 27 kOe further confirmed the face-centered tetrag on al(fet)phase in good agreement with the ordered nano structures.TheFePt NPs can be used as electrocatalysts to catalyze oxygen reduction reaction(ORR)in an O2·saturated 0.1 M HClO4 solution andhydrogen evolution reaction(HER)in the 0.5 M H2SO4 electrolyte with much better performance than commercial Pt/C,and showedquite high stability after 10,000 cycles.The strategy utilizing orga no metallic precursors to prepare metal alloy NPs was dem on strated tobe a reliable approach for improving the catalytic efficiency in fuel cells.

Pt-Ni nanourchins as electrocatalysts for oxygen reduction reaction

Pt-Ni bimetallic alloys with various nanos-tructures have shown excellent activity toward oxygen reduction reaction （ORR）. The ORR activity is highly dependent on the structure of the catalyst. In this paper, Pt-Ni nanourchins were synthesized with an average size of 50 nm consisting of 10-20 nanorods and nanooctahedra by adjusting the synthesis condition. The formation of Pt-Ni nanourchins is mainly dependent on the adding order of solvents （benzyl ether, oleylamine and oleic acid）. Pt-Ni nanourchins present a reasonable high ORR activity （0.81 A/mg at 0.9 V）.

Boosting the activity of Fe–N_x moieties in Fe–N–C electrocatalysts via phosphorus doping for oxygen reduction reaction

The Fe–N–C material is a promising non-noblemetal electrocatalyst for oxygen reduction reaction(ORR).Further improvement on the ORR activity is highly desired in order to replace Pt/C in acidic media.Herein,we developed a new-type of single-atom Fe–N–C electrocatalyst,in which Fe–Nxactive sites were modified by P atoms.The half-wave potential of the optimized material reached 0.858 V,which is 23 mV higher than that of the pristine one in a 0.1 mol L-1 HClO4 solution.Density functional theory(DFT)calculations revealed that P-doping can reduce the thermodynamic overpotential of the rate determining step and consequently improve the ORR activity.