Revealing the Indispensable Role of In Situ Electrochemically Reconstructed Mn(II)/Mn(III) in Improving the Performance of Lithium-Carbon Dioxide Batteries.

Li-CO2 batteries are regarded as promising high-energy-density energy conversion and storage devices, but their practicability is severely hindered by the sluggish CO2 reduction/evolution reaction (CORR/COER) kinetics. Due to the various crystal structures and unique electronic configuration, Mn-based cathode catalysts have shown considerable competition to facilitate CORR/COER. However, the specific active sites and regulation principle of Mn-based catalysts remain ambiguous and limited. Herein, this work designs novel Mn dual-active sites (MOC) supported on N-doped carbon nanofibers and conduct a comprehensive investigation into the underlying relationship between different Mn active sites and their electrochemical performance in Li-CO2 batteries. Impressively, this work finds that owing to the in situ generation and stable existence of Mn(III), MOC undergoes obvious electrochemical reconstruction during battery cycling. Moreover, a series of characterizations and theoretical calculations demonstrate that the different electronic configurations and coordination environments of Mn(II) and Mn(III) are conducive to promoting CORR and COER, respectively. Benefiting from such a modulating behavior, the Li-CO2 batteries deliver a high full discharge capacity of 10.31 mAh cm-2, and ultra-long cycle life (327 cycles/1308 h). This fundamental understanding of MOC reconstruction and the electrocatalytic mechanisms provides a new perspective for designing high-performance multivalent Mn-integrated hybrid catalysts for Li-CO2 batteries.

Identifying the Active Sites in MoSi2@MoO3 Heterojunctions for Enhanced Hydrogen Evolution.

Developing Two-dimensional (2D) Mo-based heterogeneous nanomaterials is of great significance for energy conversion, especially in alkaline hydrogen evolution reaction (HER), however, it remains a challenge to identify the active sites at the interface due to the structure complexity. Herein, the real active sites are systematically explored during the HER process in varied Mo-based 2D materials by theoretical computational and magnetron sputtering approaches first to filtrate the candidates, then successfully combined the MoSi2 and MoO3 together through Oxygen doping to construct heterojunctions. Benefiting from the synergistic effects between the MoSi2 and MoO3, the obtained MoSi2@MoO3 exhibits an unprecedented overpotential of 72 mV at a current density of 10 mA cm-2. Density functional theory calculations uncover the different Gibbs free energy of hydrogen adsorption (ΔGH*) values achieved at the interfaces with different sites as adsorption sites. The results can facilitate the optimization of heterojunction electrocatalyst design principles for the Mo-based 2D materials.

MOF-Derived CoSe2 Nanoparticles/Carbonized Melamine Foam as Catalytic Cathode Enabling Flexible Li-CO2 Batteries with High Energy Efficiency and Stable Cycling.

Rechargeable aprotic Li-CO2 batteries have aroused worldwide interest owing to their environmentally friendly CO2 fixation ability and ultra-high specific energy density. However, its practical applications are impeded by the sluggish reaction kinetics and discharge product accumulation during cycling. Herein, a flexible composite electrode comprising CoSe2 nanoparticles embedded in 3D carbonized melamine foam (CoSe2 /CMF) for Li-CO2 batteries is reported. The abundant CoSe2 clusters can not only facilitate CO2 reduction/evolution kinetics but also serve as Li2 CO3 nucleation sites for homogeneous discharge product growth. The CoSe2 /CMF-based Li-CO2 battery exhibits a large initial discharge capacity as high as 5.62 mAh cm-2 at 0.05 mA cm-2 , a remarkably small voltage gap of 0.72 V, and an ultrahigh energy efficiency of 85.9% at 0.01 mA cm-2 , surpassing most of the noble metal-based catalysts. Meanwhile, the battery demonstrates excellent cycling stability of 1620 h (162 cycles) at 0.02 mA cm-2 with an average overpotential of 0.98 V and energy efficiency of 85.4%. Theoretical investigations suggest that this outstanding performance is attributed to the suitable CO2 /Li adsorption and low Li2 CO3 decomposition energy. Moreover, flexible Li-CO2 pouch cell with CoSe2 /CMF cathode displays stable power output under different bending deformations, showing promising potential in wearable electronic devices.

Characterization of A π-π stacking cocrystal of 4-nitrophthalonitrile directed toward application in photocatalysis.

Photoexcitation of the electron-donor-acceptor complexes have been an effective approach to achieve radicals by triggering electron transfer. However, the catalytic version of electron-donor-acceptor complex photoactivation is quite underdeveloped comparing to the well-established utilization of electronically biased partners. In this work, we utilize 4-nitrophthalonitrile as an electron acceptor to facilitate the efficient π-stacking with electron-rich aromatics to form electron-donor-acceptor complex. The characterization and energy profiles on the cocrystal of 4-nitrophthalonitrile and 1,3,5-trimethoxybenzene disclose that the electron transfer is highly favorable under the light irradiation. This electron acceptor catalyst can be efficiently applied in the benzylic C-H bond photoactivation by developing the Giese reaction of alkylanisoles and the oxidation of the benzyl alcohols. A broad scope of electron-rich aromatics can be tolerated and a mechanism is also proposed. Moreover, the corresponding π-anion interaction of 4-nitrophthalonitrile with potassium formate can further facilitate the hydrocarboxylation of alkenes efficiently.

Promoting hydrophilic cupric oxide electrochemical carbon dioxide reduction to methanol via interfacial engineering modulation.

Copper-based catalysts have been extensively investigated in electrochemical carbon dioxide (CO2) reduction to promote carbon products generated by requiring multiple electron transfer. However, hydrophilic electrodes are unfavourable for CO2 mass transfer and preferentially hydrogen (H2) evolution in electrochemical CO2 reduction. In this paper, a hydrophilic cupric oxide (CuO) electrode with a grassy morphology was prepared. CuO-derived Cu was confirmed as the active site for electrochemical CO2 reduction through wettability modulation. To enhance the intrinsic catalytic activity, a metal-oxide heterogeneous interface was created by engineering modulation at the interface, involving the loading of palladium (Pd) on CuO (CuO/Pd). Both the electrochemically active area and the electron transfer rate were enhanced by Pd loading, and significantly the reduced work function further facilitated the electron transfer between the electrode surface and the electrolyte. Consequently, the CuO/Pd electrode exhibited excellent excellent performance in electrochemical CO2 reduction, achieving a 54 % Faraday efficiency at -0.65 V for methanol (CH3OH). The metal-oxide interfacial effect potentially improves the intrinsic catalytic activity of hydrophilic CuO electrodes in electrochemical CO2 reduction, providing a conducive pathway for optimizing hydrophilic oxide electrodes in this process.

Highly Electrically Conductive Polyiodide Ionic Liquid Cathode for High-Capacity Dual-Plating Zinc-Iodine Batteries.

Zinc-iodine batteries are one of the most intriguing types of batteries that offer high energy density and low toxicity. However, the low intrinsic conductivity of iodine, together with high polyiodide solubility in aqueous electrolytes limits the development of high-areal-capacity zinc-iodine batteries with high stability, especially at low current densities. Herein, we proposed a hydrophobic polyiodide ionic liquid as a zinc-ion battery cathode, which successfully activates the iodine redox process by offering 4 orders of magnitude higher intrinsic electrical conductivity and remarkably lower solubility that suppressed the polyiodide shuttle in a dual-plating zinc-iodine cell. By the molecular engineering of the chemical structure of the polyiodide ionic liquid, the electronic conductivity can reach 3.4 × 10-3 S cm-1 with a high Coulombic efficiency of 98.2%. The areal capacity of the zinc-iodine battery can achieve 5.04 mAh cm-2 and stably operate at 3.12 mAh cm-2 for over 990 h. Besides, a laser-scribing designed flexible dual-plating-type microbattery based on a polyiodide ionic liquid cathode also exhibits stable cycling in both a single cell and 4 × 4 integrated cell, which can operate with the polarity-switching model with high stability.

Hierarchical-Pore-Stabilization Strategy for Fabricating 18.3 wt% High-Loading Single-Atom Catalyst for Oxygen Reduction Reaction.

Metal single-atom catalysts (M-SACs) attract extraordinary attention for promoting oxygen reduction reaction (ORR) with 100% atomic utilization. However, low metal loading (usually less than 2 wt%) limits their overall catalytic performance. Herein, a hierarchical-structure-stabilization strategy for fabricating high-loading (18.3%) M-SACs with efficient ORR activity is reported. Hierarchical pores structure generated with high N content by SiO2 can provide more coordination sites and facilitate the adsorption of Fe3+ through mesoporous and confinement effect of it stabilizes Fe atoms in micropores on it during pyrolysis. High N content on hierarchical pores structure could provide more anchor sites of Fe atoms during the subsequent secondary pyrolysis and synthesize the dense and accessible Fe-N4 sites after subsequent pyrolysis. In addition, Se power is introduced to modulate the electronic structure of Fe-N4 sites and further decrease the energy barrier of the ORR rate-determining step. As a result, the Fe single atom catalyst delivers unprecedentedly high ORR activity with a half-wave potential of 0.895 V in 0.1 M KOH aqueous solution and 0.791 V in 0.1 M HClO4 aqueous solution. Therefore, a hierarchical-pore-stabilization strategy for boosting the density and accessibility of Fe-N4 species paves a new avenue toward high-loading M-SACs for various applications such as thermocatalysis and photocatalysis.

Directing (110) Oriented Lithium Deposition through High-flux Solid Electrolyte Interphase for Dendrite-free Lithium Metal Batteries.

Controlling lithium (Li) electrocrystallization with preferred orientation is a promising strategy to realize highly reversible Li metal batteries (LMBs) but lack of facile regulation methods. Herein, we report a high-flux solid electrolyte interphase (SEI) strategy to direct (110) preferred Li deposition even on (200)-orientated Li substrate. Bravais rule and Curie-Wulff principle are expanded in Li electrocrystallization process to decouple the relationship between SEI engineering and preferred crystal orientation. Multi-spectroscopic techniques combined with dynamics analysis reveal that the high-flux CF3 Si(CH3 )3 (F3 ) induced SEI (F3 -SEI) with high LiF and -Si(CH3 )3 contents can ingeniously accelerate Li+ transport dynamics and ensure the sufficient Li+ concentration below SEI to direct Li (110) orientation. The induced Li (110) can in turn further promote the surface migration of Li atoms to avoid tip aggregation, resulting in a planar, dendrite-free morphology of Li. As a result, our F3 -SEI enables ultra-long stability of Li||Li symmetrical cells for more than 336 days. Furthermore, F3 -SEI modified Li can significantly enhance the cycle life of Li||LiFePO4 and Li||NCM811 coin and pouch full cells in practical conditions. Our crystallographic strategy for Li dendrite suppression paves a path to achieve reliable LMBs and may provide guidance for the preferred orientation of other metal crystals.

Application value of tumor necrosis factor inhibitors in in vitro fertilization-embryo transfer in infertile women with polycystic ovary syndrome.

BACKGROUND: Clinical value of tumor necrosis factor (TNF) inhibitors in in vitro fertilization-embryo transfer (IVF-ET) in infertile women with polycystic ovary syndrome (PCOS) was investigated in this study. METHODS: A retrospective analysis was performed on the clinical data of 100 PCOS patients who received IVF-ET for the first time at Hebei Institute of reproductive health science and technology from January 2010 to June 2020. The patients were divided into Inhibitor group and Control group according to whether they were treated with or without TNF inhibitors. Next, the two groups were subject to comparison in terms of the days of gonadotropin (Gn) use, total dosage of Gn, trigger time, hormone level and endometrial condition on the day of human chorionic gonadotropin (HCG) injection, the effects of two different regimens on controlled ovarian hyperstimulation (COH) and pregnancy outcomes. RESULTS: There were no significant differences in baseline characteristics between the two groups, including age, duration of infertility, body mass index (BMI), ovarian volume, antral follicle count, and basal hormone levels. Compared with the Control group, the days of Gn use and trigger time of patients in the Inhibitor group were significantly shortened, and the total Gn dosage was notably reduced. In terms of sex hormone levels on the HCG injection, the Inhibitor group displayed much lower serum estradiol levels while higher serum luteinizing hormone and progesterone (P) levels than the Control group. Notably, the high-quality embryo rate was also significantly increased with the use of TNF inhibitors. However, significant differences were not observed in endometrial thickness (on the day of HCG injection), proportion of endometrial A, B and C morphology (on the day of HCG injection), cycle cancellation rate, number of oocytes retrieved, fertilization rate, and cleavage rate between the two groups. Importantly, the clinical pregnancy rate in the Inhibitor group was significantly higher than that in the Control group, but there was no significant difference in the biochemical pregnancy rate, early abortion rate, multiple birth rate, ectopic pregnancy rate and number of live births between the two groups. CONCLUSION: Collectively, after application of TNF-α inhibitor regimen, superior overall treatment effect can be observed in infertile PCOS patients receiving IVF-ET. Therefore, TNF inhibitors have certain application value in IVF-ET in infertile women with PCOS.

Clinical meaning of serum trimethylamine oxide, N-terminal-pro-brain natriuretic peptide, hypoxia-inducible factor-1a and left ventricular function and pregnancy outcome in patients with pregnancy-induced hypertension.

Background: To figure out the clinical meaning of serum trimethylamine oxide (TMAO), N-terminal-pro-brain natriuretic peptide (NT-proBNP) and hypoxia-inducible factor-1a (HIF-1a) with left ventricular function and pregnancy outcome in patients with pregnancy-induced hypertension. Methods: From January 2018 to October 2020, 117 patients with gestational hypertension were taken as the research objects and grouped into the gestational hypertension (pregnancy-induced hypertension, 55 cases), mild preeclampsia (mild PE, 43 cases) and severe preeclampsia (severe PE, 19 cases) in the light of the severity of the disease. Analysis of the relation of serum TMAO, NT-proBNP and HIF-1a with the severity of disease and cardiac function indexes in patients with gestational hypertension was conducted. All patients were followed up to the end of pregnancy, and the predictive value of serum TMAO, NT-proBNP and HIF-1a on pregnancy outcome in patients was analyzed. Results: Serum TMAO and NT-proBNP of patients were elevated, while HIF-1a was reduced with the severity of the disease (P < 0.05). Serum TMAO and NT-proBNP in patients with gestational hypertension were positively correlated but HIF-1a was negatively correlated with the severity of the disease (P < 0.05). Left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) were elevated in gestational hypertension patients, while ejection fraction (LVEF) was reduced with the severity of disease (P < 0.05). Serum TMAO, NT-proBNP and HIF1a were associated with LVEDV, LVESV and LVEF values in patients with gestational hypertension (P < 0.05). Serum TMAO and NT-proBNP were elevated but HIF-1a was reduced in patients with a poor pregnancy outcome (P < 0.05). The AUC of the combined detection of serum TMAO, NT-proBNP and HIF-1a on pregnancy outcome was greater (P < 0.05). Conclusions: Serum TMAO, NT-proBNP and HIF-1a in patients with gestational hypertension are associated with disease severity and cardiac function, and have predictive and evaluative values for disease severity and pregnancy outcome.

Isolated Metalloid Tellurium Atomic Cluster on Nitrogen-Doped Carbon Nanosheet for High-Capacity Rechargeable Lithium-CO2 Battery.

Rechargeable Li-CO2 battery represents a sustainable technology by virtue of CO2 recyclability and energy storage capability. Unfortunately, the sluggish mass transport and electron transfer in bulky high-crystalline discharge product of Li2 CO3 , severely hinder its practical capacity and rechargeability. Herein, a heterostructure of isolated metalloid Te atomic cluster anchored on N-doped carbon nanosheets is designed (TeAC @NCNS) as a metal-free cathode for Li-CO2 battery. X-ray absorption spectroscopy analysis demonstrates that the abundant and dispersed Te active centers can be stabilized by C atoms in form of the covalent bond. The fabricated battery shows an unprecedented full-discharge capacity of 28.35 mAh cm-2 at 0.05 mA cm-2 and long-term cycle life of up to 1000 h even at a high cut-off capacity of 1 mAh cm-2 . A series of ex situ characterizations combined with theoretical calculations demonstrate that the abundant Te atomic clusters acting as active centers can drive the electron redistribution of carbonate via forming TeO bonds, giving rise to poor-crystalline Li2 CO3 film during the discharge process. Moreover, the efficient electron transfer between the Te centers and intermediate species is energetically beneficial for nucleation and accelerates the decomposition of Li2 CO3 on the TeAC @NCNS during the discharge/charge process.

Intercalated Gold Nanoparticle in 2D Palladium Nanosheet Avoiding CO Poisoning for Formate Production under a Wide Potential Window.

The electrochemical CO2 reduction into formate acid over Pd-based catalysts under a wide potential window is a challenging task; CO poisoning commonly occurring on the vulnerable surface of Pd must be overcome. Herein, we designed a two-dimensional (2D) AuNP-in-PdNS electrocatalyst, in which the Au nanoparticles are intercalated in Pd nanosheets, for formate production under a wide potential window from -0.1 to -0.7 V versus a reversible hydrogen electrode. Based on the X-ray absorption spectra (XAS) characterizations, CO accumulation detection, and CO stripping voltammetry measurements, we observed that the intercalated Au nanoparticles could effectively avoid the CO formation and boost the formate production on the Pd nanosheet surface by regulating its electronic structure.

Perceived neighborhood environment and depressive symptoms among older adults living in Urban China: The mediator role of social capital.

An increasing number of studies have focused on the relationship between neighbourhood environment and depressive symptoms among older people. However, the underlying mechanisms are still unclear. This study examined the association between neighbourhood environment and depressive symptoms among older urban Chinese adults and the mediator role of social capital in this association. Using a quota sampling approach, 472 respondents aged 60 years or older were recruited from 23 urban communities of Shanghai, China, in 2020. Depressive symptoms were measured with the Center for Epidemiologic Studies Depression Scale. Social capital was measured by two latent constructs: cognitive social capital (e.g., trust, reciprocity, belongingness) and structural social capital (e.g., memberships, social participation). Perceived physical neighbourhood environment was assessed in terms of health care, security, and public transportation status. Structural equation modelling was conducted to test the study hypotheses. Health care services in the community had a direct effect on depressive symptoms (ß = -0.097, p < .05). Cognitive social capital played a mediator role in the relationship between physical neighbourhood environment and depressive symptoms (community health care: ß = -0.124, p < .01; community security: ß = -0.284, p < .01). The mediator effect of structural social capital in the relationship between physical neighbourhood environment and depressive symptoms was not significant. The findings highlight the role of physical neighbourhood environment in fostering community-based social capital and promoting mental health among older adults in urban China. Policy strategies could focus on improving community health care and security to promote mental health.

Curved periodic ripples fabricated by double time-delayed femtosecond laser beams on the silicon surface.

Laser-induced periodic surface structure (LIPSS) is an important, high-throughput surface nano-structuring method, which has been used to fabricate various functional surfaces. In this paper, we fabricate double time-delayed orthogonally polarized femtosecond laser beams with a fixed beam power ratio of 1.5:1 that are employed to irradiate the silicon surface and curved periodic ripples with a sub-wavelength period. It is found that the local orientation of the ripples on the silicon surface can be modulated in a range of 0-80° by adjusting the fabrication parameters, such as the laser fluence, the target scanning speed, and the time delay between double laser beams. The transition from the curved ripples to the straight ripples can be achieved by increasing the target scanning speed. Different from previous studies that the curved periodic ripples are fabricated by modulating the laser polarization, the method demonstrated here utilizes the interaction between the linearly polarized subsequent laser beam and the preceding laser beam excited silicon to form curved ripples.

Promoting Bifunctional Water Splitting by Modification of the Electronic Structure at the Interface of NiFe Layered Double Hydroxide and Ag.

Electrochemical water splitting is a promising method for the renewable production of high-purity hydrogen via the hydrogen evolution reaction (HER). Ni-Fe layered double hydroxides (Ni-Fe LDHs) are highly efficient materials for mediating the oxygen evolution reaction (OER), a half-reaction for water splitting at the anode, but LDHs typically display poor HER performance. Here, we report the preparation of self-organized Ag@NiFe layered double hydroxide core-shell electrodes on Ni foam (Ag@NiFe/NF) prepared by galvanic etching for mediating both the HER and OER (bifunctional water-splitting electrocatalysis). This synthetic strategy allowed for the preparation of organized hierarchical architectures which displayed improved the electrochemical performance by tuning the electronic structure of the catalyst and increasing the surface area utilization. X-ray photoelectron spectroscopy (XPS) and theoretical calculations revealed that electron transfer from the Ni-Fe LDH to Ag influenced the adsorption of the reaction intermediates leading to enhanced catalytic activity. The Ag@NiFe/NF electrode displayed overpotentials as low as 180 and 80 mV for oxygen and hydrogen evolution, respectively, at a current density of 10 mA cm-2, and improvements in the specific activity by ∼5× and ∼1.5× for the oxygen and hydrogen evolution reaction, respectively, compared to benchmark NiFe hydroxide materials. Additionally, an integrated water-splitting electrolyzer electrode can be driven by an AA battery.

An Experimental Study on Rapid Localization of the Atrioventricular Node During Open-Heart Surgery.

BACKGROUND: To verify the validity and feasibility of using a mechanical compression method to locate the atrioventricular node in open-heart surgery. METHODS: Ten healthy miniature pigs were used to establish an animal model of the beating heart under cardiopulmonary bypass. During the operation, the atrioventricular node and its surrounding areas were stimulated by mechanical compression (mechanical compression method), and the occurrence of complete atrioventricular block was judged by real-time electrocardiograph monitoring and direct observation of the heart rhythm to identify the position of the atrioventricular node. The final localization of the atrioventricular node was determined using the iodine staining method, and the results were used as the "gold standard" to test the effectiveness and feasibility of the mechanical compression method for locating the atrioventricular node. RESULTS: With the beating heart model, complete atrioventricular block occurred after mechanical compression of the "atrioventricular node" area in 10 pigs. Nine pigs regained normal conduction immediately after the compression was released, and one pig failed to recover. No atrioventricular block or other arrhythmias occurred after mechanical compression of the "non-atrioventricular node" area. The sensitivity of the method was 86.6%, specificity was 100.0%, misdiagnosis rate was 0.0%, missed diagnosis rate was 13.4%, positive predictive value was 100.0%, negative predictive value was 97.9%, positive likelihood ratios were +∞, negative likelihood ratios were 13.4%, accuracy was 98.1%, and diagnostic odds ratio was +∞. CONCLUSION: This study innovatively proposes the application of the mechanical compression method to locate the atrioventricular node during operation and preliminarily proves that this method is effective and feasible through animal experiments.

Ionic liquid assisted electrochemical coating zinc nanoparticles on carbon cloth as lithium dendrite suppressing host.

The application of lithium metal anode with high specific capacity and energy density is limited by the volume expansion and pulverization caused by dendrite growth during cycle process. We propose a composite lithium anode by immersing molten lithium on the flexible three-dimensional (3D) carbon cloth scaffold with the zinc nanoparticles. The lithiophilic zinc nanoparticles layer of framework is synthesized by fast and easy electrochemical deposition from ionic liquid avoiding high temperature, high pressure and toxic reagent. The lithium is infused into the 3D lithiophilic framework, the composite anode is obtained. The steady network structure can confine the lithium and lead to Li dendrite restraining and reducing volume change due to the low interfacial resistance and reduce the effective current density, which induced the homogeneous Li growth. Benefiting from this, the Li infused 3D carbon cloth-Zn symmetric battery exhibits a low stripping/plating overpotential (~30 mV) and can be stable over 900 h at 1 mA cm-2. The Li//LiFePO4 battery delivers higher reversible capacity (140 mAh g-1 at 2 C and 120 mAh g-1 at 5 C) and stable cycling for 1500 and 2000 cycles than bare Li.

Deep Phase Transition of MoS2 for Excellent Hydrogen Evolution Reaction by a Facile C-Doping Strategy.

Metallic 1T-phase MoS2 is considered to be the ideal electrocatalyst to carry out hydrogen evolution reaction (HER) because of favorable conductivity and sufficient active site compared with 2H-phase MoS2. Nevertheless, 1T-phase MoS2 is conventionally synthesized in a complicated process, with the production of an unstable product, which hinders their practical applications. Herein, we propose a facile approach through a carbon-doping-induced phase transition to obtain highly stable 1T-2H mixed MoS2 nanosheets. The phase transition process is characterized by Raman and X-ray photoelectron spectroscopy, as well as high-resolution transmission electron microscopy images and delivers a high phase purity of ∼60% for 1T-MoS2. According to density functional theory simulations and experimental results, C-doped 1T-2H mixed MoS2 has the advantages of abundant active sites, facilitated charge transfer rate, and high activity toward HER. The obtained C-doped MoS2 exhibits a superb HER electrocatalytic performance, with a current density of 10 mA cm-2 and the overpotential as low as 40 mV in 1 M KOH solution, and brilliant stability.

A high-performance mesoporous carbon supported nitrogen-doped carbon electrocatalyst for oxygen reduction reaction.

Investigating low-cost and highly active electrocatalysts for oxygen reduction reactions (ORR) is of crucial importance for energy conversion and storage devices. Herein, we design and prepare mesoporous carbon supported nitrogen-doped carbon by pyrolysis of polyaniline coated on CMK-3. This electrocatalyst exhibits excellent performance towards ORR in alkaline media. The optimized nitrogen-doped mesoporous electrocatalyst show an onset potential (E onset) of 0.95 V (versus reversible hydrogen electrode (RHE)) and half-wave potential (E 1/2) of 0.83 V (versus RHE) in 0.1 M KOH. Furthermore, the as-prepared catalyst presents superior durability and methanol tolerance compared to commercial Pt/C indicating its potential applications in fuel cells and metal-air batteries.

Surface-rough Fe-N/C composite wrapped on carbon nanotubes as efficient electrocatalyst for oxygen reduction reaction.

Fe-N/C composites are considered one of the most promising non-precious-metal electrocatalysts for oxygen reduction reaction (ORR). In this paper, we fabricate a novel and efficient carbon nanotube (CNT)-supported Fe-N/C composite catalyst, via the surface-self-polymerization of polydopamine and then the incorporation with Fe species on CNTs, followed by the pyrolysis process. The obtained catalyst demonstrates excellent electrocatalytic performance towards ORR in alkaline media. The modification of Fe-incorporated nitrogen-rich-carbons (Fe-CNx) on CNTs lowers the ORR half-wave-potential by ∼190 mV, giving this catalyst with an onset ORR potential of 0.95 V (versus reversible hydrogen electrode (RHE)), a half-wave potential of 0.82 V (versus RHE), and the limiting current density of 5.39 mA cm-2 in 0.1 M KOH. The performance of the as-prepared catalyst is comparatively better than the commercially available Pt/C in terms of positive half-wave potential and larger limiting current, superior durability, and higher tolerance to the methanol.