Electrocatalytic Performance For Oxygen Reduction Reaction Research Articles

Linker Mediated Electronic-State Manipulation of Conjugated Organic Polymers Enabling Highly Efficient Oxygen Reduction.

Conjugated polymers with tailorable composition and microarchitecture are propitious for modulating catalytic properties and deciphering inherent structure-performance relationships. Herein, we report a facile linker engineering strategy to manipulate the electronic states of metallophthalocyanine conjugated polymers and uncover the vital role of organic linkers in facilitating electrocatalytic oxygen reduction reaction (ORR). Specifically, a set of cobalt phthalocyanine conjugated polymers (CoPc-CPs) wrapped onto carbon nanotubes (denoted CNTs@CoPc-CPs) are judiciously crafted via in situ assembling square-planar cobalt tetraaminophthalocyanine (CoPc(NH2)4) with different linear aromatic dialdehyde-based organic linkers in the presence of CNTs. Intriguingly, upon varying the electronic characteristic of organic linkers from terephthalaldehyde (TA) to 2,5-thiophenedicarboxaldehyde (TDA) and then to thieno/thiophene-2,5-dicarboxaldehyde (bTDA), their corresponding CNTs@CoPc-CPs exhibit gradually improved electrocatalytic ORR performance. More importantly, theoretical calculations reveal that the charge transfer from CoPc units to electron-withdrawing linkers (i.e., TDA and bTDA) drives the delocalization of Co d-orbital electrons, thereby downshifting the Co d-band energy level. Accordingly, the active Co centers with more positive valence state exhibit optimized binding energy toward ORR-relevant intermediates and thus a balanced adsorption/desorption pathway that endows significant enhancement in electrocatalytic ORR. This work demonstrates a molecular-level engineering route for rationally designing efficient polymer catalysts and gaining insightful understanding of electrocatalytic mechanisms.

Linker Mediated Electronic‐State Manipulation of Conjugated Organic Polymers Enabling Highly Efficient Oxygen Reduction

AbstractConjugated polymers with tailorable composition and microarchitecture are propitious for modulating catalytic properties and deciphering inherent structure‐performance relationships. Herein, we report a facile linker engineering strategy to manipulate the electronic states of metallophthalocyanine conjugated polymers and uncover the vital role of organic linkers in facilitating electrocatalytic oxygen reduction reaction (ORR). Specifically, a set of cobalt phthalocyanine conjugated polymers (CoPc‐CPs) wrapped onto carbon nanotubes (denoted CNTs@CoPc‐CPs) are judiciously crafted via in situ assembling square‐planar cobalt tetraaminophthalocyanine (CoPc(NH2)4) with different linear aromatic dialdehyde‐based organic linkers in the presence of CNTs. Intriguingly, upon varying the electronic characteristic of organic linkers from terephthalaldehyde (TA) to 2,5‐thiophenedicarboxaldehyde (TDA) and then to thieno/thiophene‐2,5‐dicarboxaldehyde (bTDA), their corresponding CNTs@CoPc‐CPs exhibit gradually improved electrocatalytic ORR performance. More importantly, theoretical calculations reveal that the charge transfer from CoPc units to electron‐withdrawing linkers (i.e., TDA and bTDA) drives the delocalization of Co d‐orbital electrons, thereby downshifting the Co d‐band energy level. Accordingly, the active Co centers with more positive valence state exhibit optimized binding energy toward ORR‐relevant intermediates and thus a balanced adsorption/desorption pathway that endows significant enhancement in electrocatalytic ORR. This work demonstrates a molecular‐level engineering route for rationally designing efficient polymer catalysts and gaining insightful understanding of electrocatalytic mechanisms.

Simultaneous Mapping of Electrocatalytic Activity and Selectivity via Hybrid Scanning Electrochemical Probe Microscopy.

Nanoscale scanning electrochemical probe microscopy started to elucidate the heterogeneity of electrocatalytic activity at electrode surfaces. However, understanding the heterogeneity in product selectivity, another crucial aspect of interfacial reactivity, remains challenging. Herein, we introduce a method combining scanning electrochemical microscopy (SECM) and scanning electrochemical cell microscopy (SECCM) to enable the spatially resolved mapping of both activity and selectivity in electrocatalysis. A dual-channel nanopipette probe was developed: one channel for activity mapping and the other for product detection with a high collection efficiency (>95%) and sensitivity. Simultaneous mapping of activity and selectivity in the oxygen reduction reaction (ORR) is demonstrated. Combined with colocalized crystal orientation mapping, we uncover the local electrocatalytic performance of ORR at different facets on polycrystalline Pt and Au. The high-resolution selectivity mapping enabled by our method with colocalized structural characterization can provide structure-activity-selectivity relationships that are often unavailable in ensemble measurement, holding promise for understanding key structural motifs controlling interfacial reactivity.

Utilizing Carbonaceous Materials Derived from [BMIM][TCM] Ionic Liquid Precursor: Dual Role as Catalysts for Oxygen Reduction Reaction and Adsorbents for Aromatics and CO2.

This work presents the synthesis of N-doped nanoporous carbon materials using the Ionic Liquid (IL) 1-butyl-3-methylimidazolium tricyanomethanide [BMIM][TCM] as a fluidic carbon precursor, employing two carbonization pathways: templated precursor and pyrolysis/activation. Operando monitoring of mass loss during pyrolytic and activation treatments provides insights into chemical processes, including IL decomposition, polycondensation reactions and pore formation. Comparatively low mass reduction rates were observed at all stages. Heat treatments indicated stable pore size and increasing volume/surface area over time. The resulting N-doped carbon structures were evaluated as electrocatalysts for the oxygen reduction reaction (ORR) and adsorbents for gases and organic vapors. Materials from the templated precursor pathway exhibited high electrocatalytic performance in ORR, analyzed using Rotating Ring-Disk electrode (RRDE). Enhanced adsorption of m-xylene was attributed to wide micropores, while satisfactory CO2 adsorption efficiency was linked to specific morphological features and a relatively high content of N-sites within the C-networks. This research contributes valuable insights into the synthesis and applications of N-doped nanoporous carbon materials, highlighting their potential in electrocatalysis and adsorption processes.

Ternary (molybdenum disulfide/graphene)/carbon nanotube nanocomposites assembled via a facile colloidal electrostatic path as electrocatalysts for the oxygen reduction reaction: Composition and nitrogen-doping play a key role in their performance

Nanocomposites have garnered attention for their potential as catalysts in electrochemical reactions vital for technologies like fuel cells, water splitting, and metal-air batteries. This work focuses on developing three-dimensional (3D) nanocomposites through aqueous phase exfoliation, non-covalent functionalization of building blocks with surfactants and polymers, and electrostatic interactions in solution leading to the nanocomposites assembly and organization. By combining molybdenum disulfide (MoS2) layers with graphene nanoplatelets (GnPs) to form a binary 2D composite (MoS2/GnP), and subsequently incorporating multiwalled carbon nanotubes (MWNTs) to create ternary 3D composites, we explore their potential as catalysts for the oxygen reduction reaction (ORR) critical in fuel cells. Characterization techniques such as X-ray photoelectron spectroscopy, scanning electron microscopy, and X-ray diffraction elucidate material composition and structure. Our electrochemical studies reveal insights into the kinetics of the reactions and structure–activity relationships. Both the (MoS2/GnP)-to-MWNT mass ratio and nitrogen-doping of GnPs (N-GnPs) play a key role on the electrocatalytic ORR performance. Notably, the (MoS2/N-GnP)/MWNT material, with a 3:1 mass ratio, exhibits the most effective ORR activity. All catalysts demonstrate good long-term stability and methanol crossover tolerance. This facile fabrication method and observed trends offer avenues for optimizing composite electrocatalysts further.

Co/Co3O4 Heterojunctions Encased in Porous N-Doped Carbon Nanocapsules for High-Performance Cathode of Rechargeable Zinc-Air Batteries.

A long-term goal of rechargeable zinc-air batteries (ZABs) has always been to design bifunctional electrocatalysts that are robust, effective, and affordable for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). It has become a feasible method to construct metal/metal oxide interfaces to achieve superior electrocatalytic performance for ORR and OER by enhanced charge transfer. In this study, Co/Co3O4 heterojunctions were successfully prepared and encased in porous N-doped mesoporous carbon (Co/Co3O4@NC) via a simple condensation-carbonization-etching method. The extensive specific surface area of Co/Co3O4@NC facilitates effective interaction between the electrolyte and the catalyst, thereby enabling sufficient exposure of active sites for the ORR and the OER, consequently enhancing the rate of transport of active species. The well-designed Co/Co3O4@NC delivers superior ORR catalytic activity with a half-wave potential of 0.82 V (vs RHE) and a low overpotential of 347 mV at 10 mA cm-2 for OER in alkaline solution. The power density of Co/Co3O4@NC-based alkaline aqueous ZAB (156.5 mW cm-2) is superior to the commercial Pt/C + IrO2-based alkaline aqueous ZAB, and the cycling stability of ZAB is up to 220 h. In addition, Co/Co3O4@NC-based ZAB shows a high power density (50.1 mW cm-2). The construction of metal/metal oxide heterojunction encased in N-doped mesoporous carbon provides a novel route for the design of bifunctional electrocatalysts for high-performance ZABs.

Solution-Plasma Synthesis and Characterization of Transition Metals and N-Containing Carbon-Carbon Nanotube Composites.

Lithium-air batteries (LABs) have a theoretically high energy density. However, LABs have some issues, such as low energy efficiency, short life cycle, and high overpotential in charge-discharge cycles. To solve these issues electrocatalytic materials were developed for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which significantly affect battery performance. In this study, we aimed to synthesize electrocatalytic N-doped carbon-based composite materials with solution plasma (SP) using Co or Ni as electrodes from organic solvents containing cup-stacked carbon nanotubes (CSCNTs), iron (II) phthalocyanine (FePc), and N-nethyl-2-pyrrolidinone (NMP). The synthesized N-doped carbon-based composite materials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). TEM observation and XPS measurements revealed that the synthesized carbon materials contained elemental N, Fe, and electrode-derived Co or Ni, leading to the successful synthesis of N-doped carbon-based composite materials. The electrocatalytic activity for ORR of the synthesized carbon-based composite materials was also evaluated using electrochemical measurements. The electrochemical measurements demonstrated that the electrocatalytic performance for ORR of N-doped carbon-based composite material including Fe and Co showed superiority to that of N-doped carbon-based composite material including Fe and Ni. The difference in the electrocatalytic performance for ORR is discussed regarding the difference in the specific surface area and the presence ratio of chemical bonding species.

A robust asymmetric diatomic electrocatalyst for oxygen reduction reaction in both acidic and alkaline media

Herein, an asymmetric diatomic site oxygen reduction reaction (ORR) electrocatalyst with atomically dispersed Fe and Cu species co-anchored on porous nitrogen-doped polyhedra carbon was successfully prepared through a facile cooperation of post-adsorption and two-step pyrolysis method. Density functional theory (DFT) calculations reveal that the asymmetric FeCu dual atomic site experiences a symmetry destruction of electron transfer due to the existing Cu-N4 sites and thus results in the electron redistribution in FeSACuSA/NC, contributing significantly to the optimization of intermediates adsorption and acceleration of kinetics during ORR process. Attributed to the structural advantages of FeSA-N4&CuSA-N4 sites and highly porous carbon matrix, the FeSACuSA/NC catalyst exhibits excellent electrocatalytic ORR performance with half-wave potentials (E1/2) of 0.86 and 0.88 V versus reversible hydrogen electrode in 0.1 M HClO4 and 0.1 M KOH solutions as well as high durability. Moreover, FeSACuSA/NC-based H2/O2 fuel cell and zinc-air battery present superior performance with high peak power density.

Synergistic effects of hierarchical porous structures and ultra-high pyridine nitrogen doping enhance the oxygen reduction reaction electrocatalytic performance of metal-free laminated lignin-based carbon

Construction of non-metallic biomass-carbon based catalysts for fuel cell air cathode applications has attracted great attention in recent years. In this work, a convenient and clean technique was developed to fabrication nitrogen-doped lignin-based hierarchical porous lamellar carbon (N-LHPC) via lignin as the carbon precursor, melamine/urea as the nitrogen source and ZnC2O4.2H2O as the chemical activator. The N-LHPC has a high specific surface area (491.5 m2 g−1) and macroporous/mesoporous/microporous structures. The nitrogen doping of N-LHPC can reach 16.37 wt%, with a high pyridinic nitrogen content of 41.39 at.%. N-LHPC exhibits a high half-wave potential (0.87 V) and a large limiting current density (5.75 mA cm−2) in 0.1 mol KOH media which is comparable to the commercial Pt/C catalysts. Furthermore, N-LHPC was assembled as air cathode catalyst for Zn-air batteries to evaluate its practical catalytic performance, and the power density was as high as 191 mW cm−2, which was superior to the 20 wt% Pt/C electrocatalyst. This research demonstrates that lignin is a promising carbon source for the fabrication of high catalytic activity and economical electrocatalysts for energy storage systems.

One pot production of Co core/carbon shell materials and their electrocatalytic properties

AbstractThe oxygen reduction reaction (ORR) is a kinetically sluggish reaction because it requires the transfer of four electrons. In this work, one‐pot process involving thermal treatment of Co(II) acetylacetonate is developed. The resulting core–shell material (Co@C‐800) consists of metallic Co cores encapsulated by carbon‐based layered shells. Morphological analysis reveals the core–shell structures, with core particles surrounded by carbon networks. Chemical characterization using various spectroscopic techniques indicates the presence of metallic Co as the major component in Co@C‐800, with minor Co species exhibiting higher oxidation states. Raman spectroscopy confirms the formation of sp2‐hybridized carbon shells. Co@C‐800 displays efficient electrocatalytic ORR performance, evidenced by high onset and half‐wave potentials. The excellent durability and stability of Co@C‐800, demonstrated through resistance to methanol poisoning and cyclic testing, suggest the potential of core–shell materials as a practical electrocatalyst.

Controlled construction of core-shell structured Prussian Blue analogues towards enhanced oxygen reduction.

Metal-organic frameworks-based electrocatalysts have been developed as highly desirable and promising candidates for catalyzing oxygen reduction reaction (ORR), which, however, usually need to be prepared at elevated temperatures and may suffer from the framework collapse in water environment largely preventing its industrial application. Herein, we demonstrate a facile low-temperature ion exchange method to synthesize Mn and Fe co-loaded Prussian blue analogues possessing core-shell structured frameworks and favorable water-tolerance. Among the catalysts prepared, the optimal HMPB-2.6Mn shows a high ORR electrocatalytic performance featuring a half-wave potential of 0.86 V and zinc-air battery power density of 119 mW cm-2, as well as negligible degradation up to 60 h, which are comparable to commercial Pt/C. Such an excellent electrocatalytic performance is attributed to the special core-shell-like structure with Mn concentrated in outer shell, and the synergetic interactions between Mn and Fe, endowing HMPB-Mn with outstanding ORR activity and good stability.

Regulating N Species in N-Doped Carbon Electro-Catalysts for High-Efficiency Synthesis of Hydrogen Peroxide in Simulated Seawater.

Electrochemical oxygen reduction reaction (ORR) is an attractive and alternative route for the on-site production of hydrogen peroxide (H2 O2 ). The electrochemical synthesis of H2 O2 in neutral electrolyte is in early studying stage and promising in ocean-energy application. Herein, N-doped carbon materials (N-Cx ) with different N types are prepared through the pyrolysis of zeolitic imidazolate frameworks. The N-Cx catalysts, especially N-C800 , exhibit an attracting 2e- ORR catalytic activity, corresponding to a high H2 O2 selectivity (≈95%) and preferable stability in 0.5m NaCl solution. Additionally, the N-C800 possesses an attractive H2 O2 production amount up to 631.2mmolg-1 h-1 and high Faraday efficiency (79.8%) in H-type cell. The remarkable 2e- ORR electrocatalytic performance of N-Cx catalysts is associated with the N species and N content in the materials. Density functional theory calculations suggest carbon atoms adjacent to graphitic N are the main catalytic sites and exhibit a smaller activation energy, which are more responsible than those in pyridinic N and pyrrolic N doped carbon materials. Furthermore, the N-C800 catalyst demonstrates an effective antibacterial performance for marine bacteria in simulated seawater. This work provides a new insight for electro-generation of H2 O2 in neutral electrolyte and triggers a great promise in ocean-energy application.

Constructing Fe‐N4 Sites through Anion Exchange‐mediated Transformation of Fe Coordination Environments in Hierarchical Carbon Support for Efficient Oxygen Reduction

AbstractMetal single atoms (SAs) anchored in carbon support via coordinating with N atoms are efficient active sites to oxygen reduction reaction (ORR). However, rational design of single atom catalysts with highly exposed active sites is challenging and urgently desirable. Herein, an anion exchange strategy is presented to fabricate Fe‐N4 moieties anchored in hierarchical carbon nanoplates composed of hollow carbon spheres (Fe‐SA/N‐HCS). With the coordinating O atoms are substituted by N atoms, Fe SAs with Fe‐O4 configuration are transformed into the ones with Fe‐N4 configuration during the thermal activation process. Insights into the evolution of central atoms demonstrate that the SAs with specific coordination environment can be obtained by modulating in situ anion exchange process. The strategy produces a large quantity of electrochemical accessible site and high utilization rate of Fe‐N4. Fe‐SA/N‐HCS shows excellent ORR electrocatalytic performance with half‐wave potential of 0.91 V (vs. RHE) in 0.1 M KOH, and outstanding performance when used in rechargeable aqueous and flexible Zn‐air batteries. The evolution pathway for SAs demonstrated in this work offers a novel strategy to design SACs with various coordination environment and enhanced electrocatalytic activity.

Constructing Fe-N4 Sites through Anion Exchange-mediated Transformation of Fe Coordination Environments in Hierarchical Carbon Support for Efficient Oxygen Reduction.

Metal single atoms (SAs) anchored in carbon support via coordinating with N atoms are efficient active sites to oxygen reduction reaction (ORR). However, rational design of single atom catalysts with highly exposed active sites is challenging and urgently desirable. Herein, an anion exchange strategy is presented to fabricate Fe-N4 moieties anchored in hierarchical carbon nanoplates composed of hollow carbon spheres (Fe-SA/N-HCS). With the coordinating O atoms are substituted by N atoms, Fe SAs with Fe-O4 configuration are transformed into the ones with Fe-N4 configuration during the thermal activation process. Insights into the evolution of central atoms demonstrate that the SAs with specific coordination environment can be obtained by modulating in situ anion exchange process. The strategy produces a large quantity of electrochemical accessible site and high utilization rate of Fe-N4 . Fe-SA/N-HCS shows excellent ORR electrocatalytic performance with half-wave potential of 0.91 V (vs. RHE) in 0.1 M KOH, and outstanding performance when used in rechargeable aqueous and flexible Zn-air batteries. The evolution pathway for SAs demonstrated in this work offers a novel strategy to design SACs with various coordination environment and enhanced electrocatalytic activity.

A Cobalt(III) Corrole with a Tethered Imidazole for Boosted Electrocatalytic Oxygen Reduction Reaction

Comprehensive SummaryDeveloping electrocatalysts with high activity and selectivity for the oxygen reduction reaction (ORR) is vital to promote the performance of the next‐generation energy technologies, which depend on the efficiency of the catalytic reduction of dioxygen. In the structure of cytochrome c oxidases (CcOs), a histidine imidazole residue binding to the axial position of Fe plays a crucial role in facilitating the selective reduction of O2 to water. Inspired by nature, we herein report on the synthesis of CoIII corrole 1 tethered with an imidazole ligand as well as its electrocatalytic ORR and O2 binding features. As compared to the imidazolium‐free analogue, complex 1 displayed remarkably boosted activity for the selective four‐electron/four‐proton (4e‐/4H+) ORR with a half‐wave potential of E1/2 = 0.82 V versus reversible hydrogen electrode (RHE) in 0.1 mol/L KOH solutions. Importantly, we demonstrate that the tethered axial imidazole ligand improves the O2 binding ability of 1 thermodynamically and dynamically, which is crucial to boost electrocatalytic ORR performance. This work presents an example to improve electrocatalytic ORR activity and selectivity of Co corroles by introducing an axial imidazole ligand to enhance the O2 binding and activation.

Copper-cobalt bimetallic conductive metal–organic frameworks as bifunctional oxygen electrocatalyst in alkaline and neutral media

The preparation of low cost bifunctional electrocatalysts that efficiently catalyze oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is a crucial step towards realizing high-performance Zn–air batteries. Herein a bimetallic CuCo-HITP (HITP = 2,3,6,7,10,11-hexaiminotriphenylene) conductive metal-organic frameworks (MOFs) was synthesized as a bifunctional electrocatalyst for OER and ORR through an effective and facile ammonia-assisted method. Structural characterization showed that the metal ions coordinated with HITP ligands through strong coordination bonds of M − N4 to construct a two-dimensional (2D) porous structure. The electrochemical tests demonstrated that CuCo-HITP had superior bifunctional OER and ORR electrocatalytic performance in both alkaline and neutral media. It should be attributed to the bimetallic synergistically effect, which lead to more active sites, faster charge transfer rate and improvement of the catalytic reaction kinetics.

High-efficiency oxygen electrocatalyst for Zn-air batteries on CoMn alloy encapsulated in N-doped carbon architectures

A low-cost efficient electrocatalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is urgently required for the commercialization of Zn-air batteries. Herein, CoMn nanoalloys encapsulated in nitrogen-doped hollow carbon architectures (CoMn@NHC) as dual electrocatalysts for Zn-air batteries were developed successfully. The obtained CoMn@NHC nanohybrid expresses excellent electrocatalytic performances for ORR (E1/2 = 0.87 V) and OER (Ei=10 = 1.51 V). More encouragingly, a homemade aqueous Zn-air battery using CoMn@NHC catalyst delivers a larger peak power density of 92.3 mW cm−2 and excellent stability of nearly 300 h, outperforming the commercial Pt/C + RuO2. The remarkable electrocatalytic performances are owing to the unique microstructure and the synergistic effect between CoMn alloy and N-doped carbon substrate. This study opens a new way for designing high-efficient bifunctional electrocatalysts for application in renewable energy facilities.

High Density Single Fe Atoms on Mesoporous N-Doped Carbons: Noble Metal-Free Electrocatalysts for Oxygen Reduction Reaction in Acidic and Alkaline Media.

It remains a challenge to develop efficient noble metal-free electrocatalysts for the oxygen reduction reaction (ORR) in various renewable energy systems. Single atom catalysts have recently drawn great attention as promising candidates both due to their high activity and their utmost atom utilization for electrocatalytic ORR. Herein, the synthesis of an efficient ORR electrocatalyst that is composed of N-doped mesoporous carbon and a high density (4.05 wt%) of single Fe atoms via pyrolysis Fe-conjugated polymer is reported. Benefiting from the abundant atomic Fe-N4 sites on its conductive, mesoporous carbon structures, this material exhibits an excellent electrocatalytic activity for ORR, with positive onset potentials of 0.93 and 0.98V in acidic and alkaline media, respectively. Its electrocatalytic performance for ORR is also comparable to that of Pt/C (20 wt%) in both media. Furthermore, it electrocatalyzes the reaction almost fully to H2 O (or barely to H2 O2 ). Additionally, it is durable and tolerates the methanol crossover reaction well. Furthermore, a proton exchange membrane fuel cell and a zinc-air battery assembled using it on their cathodedeliver high maximum power densities (320 and 91mW cm-2 , respectively). Density functional theory calculation reveals that the material's decent electrocatalytic performance for ORR is due to its atomically dispersed Fe-N4 sites.

Co3O4 Supported on Graphene-like Carbon by One-Step Calcination of Cobalt Phthalocyanine for Efficient Oxygen Reduction Reaction under Alkaline Medium

Exploiting cost-effective and durable non-platinum electrocatalysts for oxygen reduction reaction (ORR) is of great significance for the development of abundant renewable energy conversion and storage technologies. Herein, a series of Co3O4 supported on graphene-like carbon (Co3O4/C) samples were firstly effectively synthesized by one-step calcination of cobalt phthalocyanine and their electrocatalytic performances were measured for ORR under an alkaline medium. By systematically adjusting the calcination temperature of cobalt phthalocyanine, we found that the material pyrolyzed at 750 °C (Co3O4/C-750) shows the best ORR electrocatalytic performance (half-wave potentials of 0.77 V (vs. RHE) in 0.1 M KOH) among all the control samples. Moreover, it displays better stability and superior methanol tolerance than commercial 20% Pt/C. The further electrochemical test results reveal that the process is close in characteristics to the four-electron ORR process on Co3O4/C-750. In addition, Co3O4/C-750 applied in the zinc-air battery presents 1.34 V of open circuit potential. Based on all the characterizations, the enhanced electrocatalytic performances of Co3O4/C-750 composite should be ascribed to the synergistic effect between Co3O4 and the graphene-like carbon layer structure produced by pyrolysis of cobalt phthalocyanine, as well as its high specific surface area.

Structurally Ordered PtNi Intermetallic Nanoparticles as Efficient and Stable Cathode Catalysts for Proton Exchange Membrane Fuel Cells.

Exploring oxygen reduction reaction (ORR) catalysts with superior electrochemical performance and long-term stability is crucial to the development of proton exchange membrane fuel cells (PEMFCs). In this work, graphited carbon with high specific surface area was obtained under relatively low temperature using Ni catalyst, then ordered nanoparticles (NPs) PtNi catalysts attaching to graphited carbon were synthesized via polyol reduction and thermal treatment. Benefiting from graphitized carbon support and appropriate order degree, PtNi/GC-700 NPs catalyst exhibits excellent electrocatalytic ORR performance with specific and mass activities as high as 2.8-fold and 3.7-fold of the commercial Pt/C catalyst, respectively. Besides, the as-prepared PtNi/GC-700 catalyst exhibits superior stability with negligible degradation after 10000 potential cycles, due to its ordered chemical structure. The work described herein highlights the potential of structurally ordered electrocatalysts for efficient and durable fuel cell cathodic catalysts.