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Ni3FeN and a N-doped carbon shell have improved electrical conductivity with the electronic structure modified through the extra electrons of nitrogen. Ni3FeN@NC in the water splitting reaction provide excellent electrochemical catalytic properties.

The oxygen evolution reaction (OER) at anode requires high overpotential and is still challenging. The metallic core-oxyhydroxide layer structure is an efficient method to lower an overpotential. We synthesized Fe rich FeCo core-Co rich FeCo oxyhydroxide layer with a different particle size of 173 nm, 225 nm, and 387 nm (FeCo 173, 225, 387) through a difference in the reduction rate of Fe/Co precursors using facile modified polyol synthesis. To investigate the effect of conductivity, CoFe2O4 nanoparticles of 80–130 nm were synthesized. Among samples, FeCo 173 showed remarkable catalytic performance of 316 mV at a current density of 10 mA/cm2 in 0.1 M KOH compared to RuO2 (408 mV), FeCo 225 (323 mV), FeCo 387 (334 mV), CoFe2O4 (382 mV). Moreover, FeCo 173 showed good stability for 60,000 s while RuO2 showed a gradual increase in overpotential to maintain 10 mA/cm2 after 15,000 s in chronopotentiometry. The excellent performance was attributed to Fe-rich metallic core, a small amount of Fe doping into CoOOH, and the synergic effect between the active site of Co rich FeCoOOH and conductive Fe rich metallic core. Following this result, it shows that the use of such FeCo electrodes has advantages in the production of hydrogen via electrochemical water oxidation.

We report successfully synthesizing two-dimensional (2D) and nanocrystalline (NC) Fe2Ni2N/rGO nanohybrid sheets (NHSs) via ammonolysis of as-prepared 2D Ni2.25Fe0.75[Fe(CN)6]2/rGO precursors. We co...

Developing high-efficiency and low-cost oxygen-evolving electrodes in anion exchange membrane (AEM) water electrolysis technology is one of the major challenges. Herein, it is demonstrated that the surface corrosion of a conventional Ni foam electrode in the presence of Fe3+ and V3+ cations can transform it into an electrode with a high catalytic performance for oxygen evolution reaction (OER). The corroded electrode consists of a ternary NiFeV layered double hydroxide (LDH) nanosheet array supported on the Ni foam surface. This NiFeV LDH electrode achieves an OER current density of 100 mA cm-2 at an overpotential of 272 mV in 1 m KOH, outperforming the IrO2 catalyst by 180 mV. Density functional theory calculations reveal that the unique structure and the presence of vanadium in NiFeV LDH play a key role in achieving improved OER activity. When coupled with a commercial Pt/C cathode catalyst, the resulting AEM water electrolyzer achieves a cell current density as high as 2.1 A cm-2 at a voltage of only 1.8 Vcell in 1 m KOH, which is similar to the performance of the proton exchange membrane water electrolyzer obtained from the IrO2 and Pt/C catalysts pair.

Background Congenital central hypoventilation syndrome (CCHS) is a rare disorder characterized by alveolar hypoventilation and autonomic dysregulation. Patients with CCHS have adequate ventilation while awake but exhibit hypoventilation while asleep. More severely affected patients exhibit hypoventilation both when awake and when asleep. Case Here, we report a case of successful spinal anesthesia and postoperative epidural analgesia in a patient with CCHS who underwent orthostatic surgery. Conclusions In patients with CCHS, anesthesia is used with the goal of minimizing respiratory depression to avoid prolonged mechanical ventilation. Regional anesthesia should be considered where appropriate. Continuous oxygen saturation and end-tidal carbon dioxide monitoring must be available.

Transition metal nitrides have received a great deal of attention as highly efficient OER catalysts due to their excellent electrical conductivity, which grants them lower overpotential values than precious metal oxide catalysts (RuO2, IrO2, etc.). Herein, we report the characteristics of Nickel-Iron nitrides, alloy heterogeneous nanostructures (Ni2Fe2N, Ni2Fe2N/Ni3Fe, Ni3Fe/Ni2Fe2N), and amorphous N-doped carbon shells differing only in nitridation temperature. Heterogeneous Nickel-Iron nitrides and alloy with amorphous N-doped carbon shells showed superior OER performance such as a low overpotential value of 251 mV at current density of 10 mA/cm2, Tafel slope of 35.0 mV/dec, and great stability even after 24 h. Additionally, this study accurately identified that the heterogeneous nanostructure and amorphous N-doped carbon shell improve the catalytic properties and durability of the Nickel-Iron nitrides and alloy nanoparticles. The morphological control strategy used to produce the heterogeneous nanostructure and amorphous N-doped carbon shell can be applied to improve electrochemical properties or encapsulation in strong alkaline solution.

Developing high-efficiency and cost-efficient electrodes for hydrogen and oxygen evolution reactions (HER and OER respectively) is a major challenge in water electrolysis technology. We developed a chemical transformation route that can produce both high-performance OER and HER electrodes by corrosion of a Ni foam and subsequent phosphidation process, which generated ternary NiFeCo layered double hydroxide (LDH) and phosphide nanosheets supported on the foam, respectively. Because of their compositions and high electrical conductivities, these ternary LDH and phosphide electrodes exhibited remarkably high activities for OER and HER, respectively, outperforming most of other catalysts reported to date. An alkaline water electrolyzer based on these electrodes achieved a current density of 10 mA/cm2 at an only 1.47 Vcell. In addition, anion exchange membrane water electrolyzer based on these electrodes reached a current density of 500 mA/cm2 at an only 1.75 Vcell.

Future energy conversion that will replace fossil energy can be expected from oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) among high-performance bi-functional electrocatalysts. Herein, a hybrid material, CoFe@N-C/MNGF containing an N-doped carbon shell on the surface of CoFe alloy nanoparticles and three-dimensional (3D) mesoporous N-doped graphene foam with exposed active sites as an electron transfer substrate has been successfully synthesized to replace noble-metal catalysts. The electrocatalytic performance of CoFe@N-C/MNGF demonstrates better OER activity in 0.1 M KOH alkaline electrolyte with a remarkably low overpotential of 330 mV and low Tafel plot 130.6 mV⋅dec-1 at a current density of 10 mA⋅cm−2. And CoFe@N-C/MNGF has considerable ORR performance in terms of catalyst activity, electron transfer number and stability, which suggests its usefulness as a suitable replacement for ORR catalysts based on noble-metal used for cathode electrode of alkaline fuel cells. In particular, it showed a potential of 0.87 V in 0.1 M KOH alkaline electrolyte and low Tafel plot 71.7 mV⋅dec-1 at 5 mA⋅cm−2 and the number of electrons (n) transferred was estimated to be 2.1–3.61 at 0.15 to 0.35 V. Based on these results, this study provides new insights into a cost-efficient non-noble metal bi-functional electrocatalyst.

Developing high-performance and low-cost oxygen-evolving electrodes is one of major challenges in electrochemical water splitting technology. We demonstrated that the aqueous-phase corrosion of a conventional Ni foam in the presence of exotic Fe3+ cations can directly transform it into an electrode with high catalytic activity and stability for oxygen evolution reaction (OER). The surface of the corroded electrode consisted of densely packed, small Ni0.75Fe2.25O4 nanoparticles with sizes less than 5 nm. This electrode required an overpotential of only 192 mV to reach an OER current density of 10 mA/cm2 in 1 M KOH, outperforming the state-of-the-art IrO2 catalyst by 73 mV. Density functional theory calculations revealed that the unique surface structure and iron composition of Ni0.75Fe2.25O4 nanoparticles play a key role in achieving an improved OER activity. When coupled with a Pt/C hydrogen-evolving catalyst, the resulting anion-exchange membrane (AEM) water electrolyzer achieved an overall water-splitting current density as high as 2.0 A/cm2 at a cell voltage of 1.9 V in 1 M KOH, which was 1.7 times that obtained from the IrO2 and Pt/C catalyst pair and also much greater than reported values from other AEM water electrolyzers. By revisiting and exploiting a traditional corrosion process, our work opens a simple, cost-effective, and scalable route to a high-performance OER electrode for efficient AEM water electrolysis.

The introduction of inorganic nanoparticles into carbon nanotube (CNT) papers can provide a versatile route to the fabrication of CNT papers with diverse functionalities, but it may lead to a reduction in their mechanical properties. Here, we describe a simple and effective strategy for the fabrication of mechanically robust magnetic CNT papers for electromagnetic interference (EMI) shielding and magnetomechanical actuation applications. The magnetic CNT papers were produced by vacuum filtration of an aqueous suspension of CNTs, CoFe2O4 nanoparticles, and poly(vinyl alcohol) (PVA). PVA plays a critical role in enhancing the mechanical strength of CNT papers. The magnetic CNT papers containing 73 wt % of CoFe2O4 nanoparticles exhibited high mechanical properties with Young’s modulus of 3.2 GPa and tensile strength of 30.0 MPa. This magnetic CNT paper was successfully demonstrated as EMI shielding paper with shielding effectiveness of ∼30 dB (99.9%) in 0.5–1.0 GHz, and also as a magnetomechanical actuator i...

In order to improve the efficiency of the water splitting system, many researchers have focused on controlling the nanostructure of the catalysts, which could reduce the overpotential value of the overall water splitting process. Herein, we report the characteristics of the overall water splitting of cobalt nitrides synthesized in the same way but differing only in the temperature of nitridation. Hierarchical phases (Co3N, Co3N/Co4N, and Co4N) and structures (mesoporous nanocubes, porous nanocubes, and aggregated particles) of CoxN with different thickness of amorphous N-doped carbon allowed CoxN to have different overpotential values (419 mV, 557 mV, and 606 mV at a current density of 10 mA∙cm−2), which is in contrast to known theoretical electrical properties. Our research about the comparison of hierarchical structure of CoxN offers the potential as advanced electrocatalysts for many materials that have not yet been morphologically controlled.

In this study, simple electrospinning combined with pyrolysis were used to fabricate transition-metal-based-nanoparticle-incorporated carbon nanofiber (CNF) electrocatalysts for a high-efficiency hydrogen evolution reaction (HER) and overall water splitting. Co-CeO2 nanoparticle-incorporated carbon nanofibers (Co-CeO2@CNF) exhibit an outstanding electrocatalytic HER performance with an overpotential and Tafel slope of 92 mV and 54 mV/dec, respectively. For the counterpart, electrolysis, we incorporate the widely used Ni2Fe catalyst with a high oxygen evolution reaction (OER) activity into the carbon nanofiber (Ni2Fe@CNF). To evaluate their electrochemical properties for the overall water splitting, Co-CeO2@CNF and Ni2Fe@CNF were used as the HER and OER electrocatalysts in an alkaline electrolyzer. With the paired Co-CeO2@CNF and Ni2Fe@CNF electrodes, an overall water splitting current density of 10 mA/cm2 was achieved by applying 1.587 V across the electrodes with a remarkably lower overpotential of 257 mV compared to that of an electrolyzer comprised of Pt/C and IrO2 electrodes (400 mV). Owing to the conformal incorporation of nanoparticles into the CNF, the electrocatalysts exhibit significant long-term durability over 70 h of overall water splitting. This study provides rational designs of catalysts with high electrochemical catalytic activity and durability to achieve overall water splitting.