Interface engineering of hierarchical flower-like N, P, O-doped NixPy self-supported electrodes for highly efficient water-to-hydrogen fuel/oxygen conversion.

Rational construction of efficient bifunctional catalysts with robust catalytic activity and durability is significant for overall water splitting (conversion between water and hydrogen fuel/oxygen) using non-precious metal systems. In this work, the hierarchically porous N, P, O-doped transition metal phosphate in the Ni foam (NF) electrode (hollow flower-like NPO/NixPy@NF) was prepared through facile hydrothermal method coupled with phosphorization treatment. The hierarchical hollow flower-like NPO/NixPy@NF electrodes exhibited high bifunctional activity and stability for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solutions. The optimized electrode showed low overpotentials of 76 and 240 mV for HER and OER to reach a current density of 10 mA cm-2, respectively. Notably, the NPO/NixPy@NF electrode only required a low voltage of 1.99 V to reach the current densities of 100 mA cm-2 with long-term stability for overall water splitting using the NPO/NixPy@NF|| NPO/NixPy@NF cell, surpassing that of the Pt/C-RuO2 (2.24 V@ 100 mA cm-2). The good catalytic and battery performance should be attributed to i) the open hierarchical structure that enhanced the mass transfer; ii) a highly conductive substrate that accelerated the electron transfer; iii) the rich heterojunction and strong synergy between Ni2P and Ni5P4 that improved the catalytic kinetic; iv) the proper-thickness amorphous phosphorus oxide nitride (PON) shell that realized the stability. This work demonstrates a promising methodology for designing bifunctional transition metal phosphides with high performance for efficient water splitting.

Light Enables the Cathodic Interface Reaction Reversibility in Solid-State Lithium-Oxygen Batteries.

Limited triple-phase boundaries arising from the accumulation of solid discharge product(s) in solid-state cathodes (SSCs) pose a challenge to high-property solid-state lithium-oxygen batteries (SSLOBs). Light-assisted SSLOBs have been gradually explored as an ingenious system; however, the fundamental mechanisms of the SSCs interface behavior remain unclear. Here, we discovered that light assistance can enhance the fast inner-sphere charge transfer in SSCs and regulate the discharge products with spherical particles generated via the surface growth model. Moreover, the high photoelectron excitation and transportation capabilities of SSCs can retard cathodic catalytic decay by avoiding structural degradation of the cathode with a reduced charge voltage. The light-induced SSLOBs exhibited excellent stability (170 cycles) with a low discharge-charge polarization overpotential (0.27 V). Furthermore, transparent SSLOBs with exceptional flexibility, mechanical stability, and multiform shapes were fabricated for theory-to-practical applications in sunlight-induced batteries. Our study opens new opportunities for the introduction of solar energy into energy storage systems.

Grain boundary and interface interaction of metal (copper/indium) oxides to boost efficient electrocatalytic carbon dioxide reduction into syngas.

Electrochemical conversion of carbon dioxide (CO2) into syngas is considered a promising approach to mitigate global warming and achieve the recycling of carbon resources. In this work, a series of core-shell metal (copper/indium) oxides with abundant grain boundaries (GBs) between the amorphous In2O3 and cubic Cu2O have been prepared by template-assisted co-precipitation method and tested for the synthesis of syngas by electrochemical CO2 reduction reaction (CO2RR). The phases of Cu2O and In2O3 are independent in bimetallic oxides and do not form any alloy oxidation phase, thus Cu2O and In2O3 can maintain their crystal structure and chemical properties in bimetallic oxides. The Cu2O and In2O3 would been completely reduced to metallic Cu and In during CO2RR. The derived copper/indium possesses the maximum FE of CO (80 %) at -0.77 V vs. reversible hydrogen electrode (RHE) and a good stability of 10 h in an H-type cell. Further applied the copper/indium oxide in the MEA reactor, the FE of CO is more than 80 % at 2.6 V and the total FE of syngas is near 100 % at all applied potentials. More importantly, the H2/CO ratios can be tuned from 1/1 to 1/4 by changing the applied voltages in MEA. Therefore, this study provides a promising strategy to promote the electrocatalytic CO2RR conversion by creating abundant grain boundaries in bimetallic oxides to regulate the ratio of H2/CO.

Regression of a large prolapsed lumbar disc herniation achieved by conservative treatment: A case report and literature review.

A common spinal condition known as lumbar disc herniation (LDH) can result in radicular and low back discomfort. A 27-year-old man was admitted to our hospital with a 6-year history of persistent low back pain, and his low back pain had recurred with radiation to his lower extremities over the last two months. An extensive right-sided paracentral disc herniation in the L5/S1 intervertebral region, which compressed the nerve root, was discovered by magnetic resonance imaging (MRI) of his lumbar spine. After receiving conservative treatment, the patient reported that his lower back discomfort and neurogenic claudication had gradually subsided after 4 months. After one year, a follow-up MRI showed that the massive, prolapsed disc herniation at the L5/S1 level had totally disappeared. The sagittal protrusion length of the L5/S1 intervertebral disc shrank from 12.35 mm to 3.49 mm. However, there remained a chance of vertebral height loss. During the course of treatment, the height of the L5/S1 intervertebral space was still slightly reduced. The intervertebral space height declined from 7.705 mm to 7.201 mm after one year of treatment. The current case and a review of the literature demonstrate that LDH can decrease with conservative therapy over a short period of time. We stress the effectiveness of conservative treatment in very select LDH cases that lack a clear surgical justification.

A biomechanical investigation of a novel intramedullary nail used to salvage failed internal fixations in intertrochanteric fractures.

PURPOSE: The ideal approach for revision surgery following femoral head salvage treatments for an intertrochanteric fracture is still up for debate. A novel variety of proximal femoral bionic intramedullary nail (PFBN) has been created in clinical practice. We aimed to compare the biomechanical results of the novel implant to conventional intramedullary and extramedullary fixation in the treatment of intertrochanteric fracture following primary internal fixation failure. METHODS: Using finite element analysis, we created a three-dimensional model of the intertrochanteric fracture's helical blade cut-out for this investigation. The PFBN 1 group, the PFBN 2 group, the PFNA group, and the DHS group were our four test groups. For each fracture group, the von Mises stress and displacements of the femur and internal fixation components were measured under 2100 N axial loads. RESULTS: The values for the femoral displacement in the PFBN1 group, PFBN2 group, PFNA group, and DHS group were 6.802 mm, 6.716 mm, 8.080 mm, and 8.679 mm, respectively. The internal implant displacement values were 6.201 mm, 6.138 mm, 7.396 mm, and 8.075 mm in the PFBN1 group, PFBN2 group, PFNA group, and DHS group, respectively. The maximum von Mises Stress in the femoral was 187.2 MPa, 85.18 MPa, 106.6 MPa, and 386.2 MPa in the PFBN1 groups, PFBN2 groups, PFNA groups, and DHS groups, respectively. In the PFBN1 groups, PFBN2 groups, PFNA groups, and DHS groups, the maximum von Mises Stress in internal fixation was 586.7 MPa, 559.8 MPa, 370.7 MPa, and 928.4.8 MPa, respectively. CONCLUSION: Our biomechanical research demonstrates that intramedullary fixation is more stable than extramedullary fixation when salvaging failed internal fixations in intertrochanteric fracture. Compared with PFNA and DHS, PFBN showed better biomechanical stability in the treatment of patients with revised intertrochanteric fractures. In light of this, we advocate PFBN fixation as the method of choice for intertrochanteric fracture revision. This result still has to be confirmed in more clinical research.

Biochar/nano-zerovalent zinc-based materials for arsenic removal from contaminated water.

In this study, we explored the potential of a newly prepared nano-zero valent zinc (nZVZn), biochar (BC)/nZVZn and BC/hydroxyapatite-alginate (BC/HA-alginate) composites for the removal of inorganic As species from water. Relatively, higher percentage removal of As(III) and As(V) was obtained by nZVZn at pH 3.4 (96% and 94%, respectively) compared to BC/nZVZn (90% and 88%) and BC/HA-alginate (88% and 80%) at pH 7.2. Freundlich model provided the best fit (R2 = up to 0.98) for As(III) and As(V) sorption data of all the sorbents, notably for nZVZn. The pseudo-second order model well-described kinetics of As(III) and As(V) (R2 = 0.99) sorption on all the sorbents. The desorption experiments demonstrated that the As removal efficiency, up to the third sorption/desorption cycle, was in the order of nZVZn ∼ BC/HA-alginate (88%) > BC/nZVZn (84%). The Fourier transform infrared spectroscopy depicted that the -OH, -COOH, Zn-O and Zn-OH surface functional groups were responsible for the sorption of As(III) or As(V) on the sorbents investigated here. This study highlights that removal of As species from water by BC/nZVZn composite can be compared with nZVZn, suggesting that integrating BC with nZVZn could efficiently remove As from As-contaminated drinking water.

This is the first study to explore the potential of a newly prepared sugarcane bagasse biochar/nano-zerovalent zinc (BC/nZVZn) based composite for the removal of inorganic arsenic (As) species from water. The results indicated high percentage removal of As(III) and As(V) from water by BC/nZVZn that were comparable to nZVZn alone.

Cu/S-Occupation Bifunctional Oxygen Catalysts for Advanced Rechargeable Zinc-Air Batteries.

The design and synthesis of low-cost and highly efficient bifunctional catalysts is an inevitable path for rechargeable zinc-air batteries (rZABs). In this work, double-carbon co-supported Co-based oxide with the Cu and S substitutions are synthesized by a one-step hydrothermal method and formed a unique honeycomb structure. As expected, the (Cu, Co)3OS3@CNT-C3N4 exhibits high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity with low overpotential (0.86 V), high power density (215 mW cm-2), and long-term discharge stability (115 h). The (Cu, Co)3OS3@CNT-C3N4-based rZAB also shows a stronger charge-discharge durability with a very low voltage gap of merely 0.5 V than that of Pt/C+RuO2. The high catalytic performances are attributed to these following reasons: (i) the porous morphology and hierarchical structure with plentiful "catalytic buffer", which accelerates the mass transfer; (ii) a high-speed electronic transmission network established by C3N4 and carbon nanotube (CNT), enhancing the conductivity; (iii) the strong synergistic effect between (Cu, Co)3OS3@CNT and C3N4, which improves the kinetics of ORR/OER; and (iv) the controllable occupation of Cu ions and S ions, which effectively regulates the CoO6 surface and increases the active site density. This work not only offers a promising ORR/OER electrode for rZAB but also provides a new pathway to understand the improvement mechanism for catalysts by the bi-ion substitutions.

Exploiting a High-Performance "Double-Carbon" Structure Co9S8/GN Bifunctional Catalysts for Rechargeable Zn-Air Batteries.

Rational synthesis of bifunctional electrocatalysts with high performance and strong durability is highly demanded rechargeable metal-air battery. In this work, ZIF-derived Co9S8/C coated with conductive graphene nanosheet (Co9S8/GN) was synthesized by a simple solvothermal method and formed a stable double-carbon structure. As expected, the prepared Co9S8/GN catalyst exhibits a high catalytic activity (ΔE: 0.88 V) and long-term durability toward both oxygen reduction reaction and oxygen evolution reaction (ORR and OER), which is even superior to the Pt/C + Ir/C mixture (0.91 V). In addition, the Zn-air battery with the Co9S8/GN catalyst showed higher power density (186 mW cm-2) and more stable charge-discharge cycling performances (2000 cycles) than the Pt/C + Ir/C (118 mW cm-2). Based on these analysis results, the favorable catalytic performance of ORR/OER should be illustrated by the following reasons: (i) large specific surface area and unique mesoporous structure, providing abundant active sites; (ii) good conductivity, accelerating the electrons transfer; and (iii) the unique stable "double-carbon" structures (metal-S-C-C), preventing the agglomeration of metal sulfide, building new quick transfer pathway, and forming the strong electron coupling ability and synergistic effect.

Bimetallic Sulfide with Controllable Mg Substitution Anchored on CNTs as Hierarchical Bifunctional Catalyst toward Oxygen Catalytic Reactions for Rechargeable Zinc-Air Batteries.

The exploitation of high-efficiency and cheap bifunctional cathode electrocatalyst is of significant importance to rechargeable zinc-air batteries. In this paper, a bimetallic sulfide coupled with a CNT ((Co, Mg)S2@CNTs) hybrid catalyst is developed via a proposed vulcanization process. The (Co, Mg)S2@CNTs) with controllable Mg substitution has a tailored crystal structure (amorphous and crystalline), which catalyzes the oxygen reduction/evolution reaction (ORR/OER). The active sites of CoS2@CNTs are activated by doping Mg ions, which accelerates the kinetics of the oxygen adsorption for ORR and oxygen desorption for OER. Meanwhile, the hybrid catalyst exhibits a unique hierarchal morphology and a "catalytic buffer", which further accelerate the mass transfer of catalytic processes. In addition, the outer wall of CNTs as substrate effectively avoid the agglomeration of (Co, Mg)S2 particles by reasonably providing adsorption sites. The inner and outer walls of CNTs form a high-speed conduction pathway, quickly transferring the electrons produced by oxygen catalytic reactions. As a result, the (Co, Mg)S2@CNTs exhibit an ORR performance comparable with commercial catalyst Pt/C-RuO2 and remarkable OER performance (Ej=10 = 1.59 V). The high power density of 268 mW cm-2 and long-term charge/discharge stability of the zinc-air battery proves the feasibility of (Co, Mg)S2@CNTs application in high-power devices.

Promoter Effects of Functional Groups of Hydroxide-Conductive Membranes on Advanced CO2 Electroreduction to Formate.

The electrochemical reduction of CO2 at ambient conditions provides a latent solution of turning waste greenhouse gases into commodity chemicals or fuels; however, a satisfactory ion-conducting membrane for maximizing the performance of a CO2 electrolyzer has not been developed. Here, we report the synthesis of a sequence of hydroxide-conductive polymer membranes, which are based on polymer composites of poly(vinyl alcohol)/Guar hydroxypropyltrimonium chloride, for use in CO2 electrolysis. The effect of different membrane functional groups, including thiophene, hydroxybenzyl, and dimethyloctanal, on the efficiency and selectivity of CO2 electroreduction to formate is thoroughly evaluated. The membrane incorporating thiophene groups exhibits the highest Faradaic efficiency of 71.5% at an applied potential of -1.64 V versus saturated calomel electrode (SCE) for formate. In comparison, membranes containing hydroxybenzyl and dimethyloctanal groups produced lower efficiencies of 67.6 and 68.6%, respectively, whereas the commercial Nafion 212 membrane was only 57.6% efficient. The improved efficiency and selectivity of membranes containing thiophene groups are attributed to a significantly increased hydroxide conductivity (0.105 S cm-1), excellent physicochemical properties, and the simultaneous attenuation of formate product crossover.

Controllable Hortensia-like MnO2 Synergized with Carbon Nanotubes as an Efficient Electrocatalyst for Long-Term Metal-Air Batteries.

The exploitation of a high-activity and low-cost bifunctional catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as the cathode catalyst is a research priority in metal-air batteries. Herein, a novel bifunctional hybrid catalyst of hortensia-like MnO2 synergized with carbon nanotubes (CNTs) (MnO2/CNTs) is controllably synthesized by reasonably designing the crystal structure and morphology as well as electronic arrangement. On the basis of these strategies, the hybrid accelerates the reaction kinetics and avoids the change of structures. As expected, MnO2/CNTs exhibit a remarkable ORR and OER activity [low ORR Tafel slope: 71 mV dec-1, low OER Tafel slope: 67 mV dec-1, and small potential difference (Δ E): 0.85 V] and a long-term stability, which should be attributed to its unique morphology, K+ ions in the 2 × 2 tunnels, and synergistic effect between MnO2 and CNTs. Notably, in zinc-air batteries (ZABs), aluminum-air batteries (AABs), and magnesium-air batteries (MABs), the composite shows high power density (ZABs: 243 mW cm-2, AABs: 530 mW cm-2, and MABs: 614 mW cm-2) and large specific capacities (793 mA h gZn-1, 918 mA h gAl-1, and 878 mA h gMg-1). Importantly, the rechargeable ZABs reveal small charge-discharge voltage drop (0.81 V) and strong cycle durability (500 h), which are better than the noble-metal Pt/C + IrO2 mixture catalyst (the voltage drop: 1.15 V at first and 2 V after 100 h). These superior performances together with the simple synthetic method of the hybrid reveal great promise in large-power energy storage and conversion equipment.

Alkaline Exchange Polymer Membrane Electrolyte for High Performance of All-Solid-State Electrochemical Devices.

As a potential solution to ubiquitous energy concerns, anion-exchange membranes (AEMs) have been widely used as the electrolyte in alkaline fuel cells (AFCs), and significant refinement of AEMs has been achieved in the past few decades. However, it remains unknown whether AEMs can be used as an electrolyte in a solid-state supercapacitor or zinc-air battery. A low-cost alkaline exchange membrane electrolyte composed of chitosan and poly(diallyldimethylammonium chloride) that possesses a high OH- conductivity (0.024 S cm-1), strong alkaline stability (216 h at 8 M KOH), good thermal stability, and low degree of anisotropic swelling, was found to provide a high electrochemical performance in all-solid-state devices. Prototypes of the solid AFC with the membrane shows superior stability over 500 h. The carbon nanotube-based all-solid-state supercapacitor with the membrane generated a rectangular cyclic voltammetry curve up to 10 V s-1 and excellent cycling stability of 4000 cycles with 84% specific capacitance retention. The all-solid-state zinc-air battery demonstrates high power density (48.9 mW cm-2). These advantages indicate that the membrane is a promising electrolyte for all-solid-state electrochemical devices.

Superior stability of a bifunctional oxygen electrode for primary, rechargeable and flexible Zn-air batteries.

Central to commercializing metal-air batteries is the development of highly efficient and stable catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this study, a composite catalyst with a unique interpenetrating network (denoted as NiCo2O4@MnO2-CNTs-3) was synthesized and exhibited better bifunctional activity (ΔE = 0.87 V) and durability than both Pt/C and Ir/C catalysts. The improved performance arises from three factors: (i) MnO2 promotes the ORR while NiCo2O4 facilitates the OER; (ii) carbon nanotubes improve the electronic conductivity; and (iii) the highly porous structure enables the adsorption-desorption of O2 and enhances the structural stability. As a result, the primary and rechargeable Zn-air battery affords a high power density and specific capacity (722 mA h g-1), an outstanding discharge stability (255 mW cm-2 after 1000 cycles) and a high cycling stability (over 2280 cycles). Electron microscopy and electrochemical analysis revealed that the degradation of the rechargeable Zn-air battery performance resulted from the damage of the air electrode and the hydrogen evolution reaction on the zinc electrode. A flexible Zn-air battery employing a solid-state electrolyte showed an exciting stability (540 cycles) and high power density (85.9 mW cm-2), suggesting that the anion exchange membrane effectively prevents the migration of Zn2+ ions and the deposition of carbonates.

Co3O4/MnO2/Hierarchically Porous Carbon as Superior Bifunctional Electrodes for Liquid and All-Solid-State Rechargeable Zinc-Air Batteries.

The design of efficient, durable, and affordable catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is very indispensable in liquid-type and flexible all-solid-state zinc-air batteries. Herein, we present a high-performance bifunctional catalyst with cobalt and manganese oxides supported on porous carbon (Co3O4/MnO2/PQ-7). The optimized Co3O4/MnO2/PQ-7 exhibited a comparable ORR performance with commercial Pt/C and a more superior OER performance than all of the other prepared catalysts, including commercial Pt/C. When applied to practical aqueous (6.0 M KOH) zinc-air batteries, the Co3O4/MnO2/porous carbon hybrid catalysts exhibited exceptional performance, such as a maximum discharge peak power density as high as 257 mW cm-2 and the most stable charge-discharge durability over 50 h with negligible deactivation to date. More importantly, a series of flexible all-solid-state zinc-air batteries can be fabricated by the Co3O4/MnO2/porous carbon with a layer-by-layer method. The optimal catalyst (Co3O4/MnO2/PQ-7) exhibited an excellent peak power density of 45 mW cm-2. The discharge potentials almost remained unchanged for 6 h at 5 mA cm-2 and possessed a long cycle life (2.5 h@5 mA cm-2). These results make the optimized Co3O4/MnO2/PQ-7 a promising cathode candidate for both liquid-type and flexible all-solid-state zinc-air batteries.

A novel composite (FMC) to serve as a durable 3D-clam-shaped bifunctional cathode catalyst for both primary and rechargeable zinc-air batteries.

Novel and highly durable air cathode electrocatalyst with three dimensional (3D)-clam-shaped structure, MnO2 nanotubes-supported Fe2O3 (Fe2O3/MnO2) composited by carbon nanotubes (CNTs) ((Fe2O3/MnO2)3/4-(CNTs)1/4) is synthesized using a facile hydrothermal process and a following direct heat-treatment in the air. The morphology and composition of this catalyst are analyzed using scanning electronic microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). The morphology characteristics reveal that flower-like Fe2O3 particles are highly dispersed on both MnO2 nanotubes and CNT surfaces, coupling all three components firmly. Electrochemical measurements indicate that the synergy of catalyst exhibit superior bi-functional catalytic activity for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as well as stability than Pt/C and IrO2 catalysts. Using these catalysts for air-cathodes, both primary and rechargeable zinc-air batteries (ZABs) are assembled for performance validation. In a primary ZAB, this 3D-clamed catalyst shows a decent open circuit voltage (OCV, ∼1.48V) and a high discharge peak power density (349mWcm-2), corresponding to a coulombic efficiency of 92%. In a rechargeable ZABs with this bifunctional catalyst, high OCV (>1.3V) and small charge-discharge voltage gap (<1.1V) are achieved along with high specific capacity (780mAhg-1 at 30mAcm-2) and robust cycle-life (1,390 cycles at cycle profile of 20mA/10min).

Self-assembly formation of Bi-functional Co3O4/MnO2-CNTs hybrid catalysts for achieving both high energy/power density and cyclic ability of rechargeable zinc-air battery.

α-MnO2 nanotubes-supported Co3O4 (Co3O4/MnO2) and its carbon nanotubes (CNTs)-hybrids (Co3O4/MnO2-CNTs) have been successfully developed through a facile two-pot precipitation reaction and hydrothermal process, which exhibit the superior bi-functional catalytic activity for both ORR and OER. The high performance is believed to be induced by the hybrid effect among MnO2 nanotubes, hollow Co3O4 and CNTs, which can produce a synergetic enhancement. When integrated into the practical primary and electrochemically rechargeable Zn-air batteries, such a hybrid catalyst can give a discharge peak power density as high as 450 mW cm(-2). At 1.0 V of cell voltage, a current density of 324 mA cm(-2) is achieved. This performance is superior to all reported non-precious metal catalysts in literature for zinc-air batteries and significantly outperforms the state-of-the-art platinum-based catalyst. Particularly, the rechargeable Zn-air battery can be fabricated into all-solid-state one through a simple solid-state approach, which exhibits an excellent peak power density of 62 mW cm(-2), and the charge and discharge potentials remain virtually unchanged during the overall cycles, which is comparable to the one with liquid electrolyte.