Layered Double Hydroxide@Polydopamine Core–Shell Nanosheet Arrays-Derived Bifunctional Electrocatalyst for Efficient, Flexible, All-Solid-State Zinc–Air Battery

Designing of highly efficient bifunctional electrocatalysts that can simultaneously catalyze the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is the key to the development of sustainable, clean energy storage, and conversion technologies. Herein, we report a flexible electrode based on Co-CoOχ/N-C nanosheet arrays (NSAs) directly grown on a carbon cloth fabricated by pyrolysis of the core–shell CoAl-LDH@polydopamine (CoAl-LDH@PDA) NSA precursor. The as-synthesized Co-CoOχ/N-C NSAs exhibit excellent bifunctional electrochemical activity for the ORR and OER, with a small potential gap (0.678 V) and excellent durability. Furthermore, a high power density (20.7 mW cm–2), superior flexibility, and cycling stability for flexible all-solid-state zinc–air battery is achieved on Co-CoOχ/N-C NSAs. The excellent performance of Co-CoOχ/N-C NSAs comes from its integrated nanosheet array architecture and the synergetic effect between Co-CoOχ and N-C. This in situ synthesis strategy builds up a general approach for fabricating other multifunctional electrodes toward a large variety of important electrochemical processes

Nitrate removal with lateral flow sulphur autotrophic denitrification reactor

<div><p>An innovative lateral flow sulphur autotrophic denitrification (LFSAD) reactor was developed in this study; the treatment performance was evaluated and compared with traditional sulphur/limestone autotrophic denitrification (SLAD) reactor. Results showed that nitrite accumulation in the LFSAD reactor was less than 1.0 mg/L during the whole operation. Denitrification rate increased with the increased initial alkalinity and was approaching saturation when initial alkalinity exceeded 2.5 times the theoretical value. Higher influent nitrate concentration could facilitate nitrate removal capacity. In addition, denitrification efficiency could be promoted under an appropriate reflux ratio, and the highest nitrate removal percentage was achieved under reflux ratio of 200%, increased by 23.8% than that without reflux. Running resistance was only about 1/9 of that in SLAD reactor with equal amount of nitrate removed, which was the prominent excellence of the new reactor. In short, this study indicated that the developed reactor was feasible for nitrate removal from waters with lower concentrations, including contaminated surface water, groundwater or secondary effluent of municipal wastewater treatment with fairly low running resistance. The innovation in reactor design in this study may bring forth new ideas of reactor development of sulphur autotrophic denitrification for nitrate-contaminated water treatment.</p></div

Data_Sheet_1_Hierarchical Hollow Co/N-C@NiCo2O4 Microsphere as an Efficient Bi-functional Electrocatalyst for Rechargeable Zn–Air Battery.doc

Zn–air batteries (ZABs) have drawn extensive attention for portable and wearable electronic devices owing to their high theoretical specific energy density and low cost. However, due to the dense packing under high mass loading, the mass/charge diffusion is seriously hindered, making their practical performance with high power density, and energy density difficult to sustain. Herein, we reported an efficient bi-functional electrocatalyst of Ni-Co mixed metal oxides incorporated with cobalt/nitrogen-doped carbon with hierarchical hollow nanostructure (H-Co/N-C@NiCo2O4). Benefiting from the advantages of this structure and composition, the H-Co/N-C@NiCo2O4 exhibits superior electrocatalytic activity and long-time durability for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The potential gap between half-wave potential in ORR and overpotential at a current density of 10 mA cm−2 in OER reaches 0.8 V, much smaller than that of most reported bi-functional electrocatalysts. Moreover, H-Co/N-C@NiCo2O4 is constructed as an air electrode for rechargeable ZAB, delivering a high power density and long cycling stability. The good linear relationship between the power density and various mass loading of H-Co/N-C@NiCo2O4 on the electrode demonstrates that the performance has been well-maintained even under high dense packing of catalysts, which offers a new pathway for the practical applications in ZAB.</p

Preparation of Fe₃O₄@SiO₂@Layered Double Hydroxide Core–Shell Microspheres for Magnetic Separation of Proteins

Three-component microspheres containing an SiO2-coated Fe3O4 magnetite core and a layered double hydroxide (LDH) nanoplatelet shell have been synthesized via an in situ growth method. The resulting Fe3O4@SiO2@NiAl-LDH microspheres display three-dimensional core–shell architecture with flowerlike morphology, large surface area (83 m2/g), and uniform mesochannels (4.3 nm). The Ni2+ cations in the NiAl-LDH shell provide docking sites for histidine and the materials exhibit excellent performance in the separation of a histidine (His)-tagged green fluorescent protein, with a binding capacity as high as 239 μg/mg. The microspheres show highly selective adsorption of the His-tagged protein from Escherichia coli lysate, demonstrating their practical applicability. Moreover, the microspheres possess superparamagnetism and high saturation magnetization (36.8 emu/g), which allows them to be easily separated from solution by means of an external magnetic field and subsequently reused. The high stability and selectivity of the Fe3O4@SiO2@NiAl-LDH microspheres for the His-tagged protein were retained over several separation cycles. Therefore, this work provides a promising approach for the design and synthesis of multifunctional LDH microspheres, which can be used for the practical purification of recombinant proteins, as well as having other potential applications in a variety of biomedical fields including drug delivery and biosensors

Hierarchical NiFe Layered Double Hydroxide Hollow Microspheres with Highly-Efficient Behavior toward Oxygen Evolution Reaction

The exploitation of highly efficiency and low-cost electrocatalysts toward oxygen evolution reaction (OER) is a meaningful route in renewable energy technologies including solar fuel and water splitting. Herein, NiFe-layered double hydroxide (NiFe-LDH) hollow microsphere (HMS) was designed and synthesized via a one-step in situ growth method by using SiO₂ as a sacrificial template. Benefiting from the unique architecture, NiFe-LDH HMS shows highly efficient OER electrocatalytic activity with a preferable current density (71.69 mA cm^–2 at η = 300 mV) and a small onset overpotential (239 mV at 10 mA cm^–2), which outperforms the 20 wt % commercial Ir/C catalyst. Moreover, it exhibits a remarkably low Tafel slope (53 mV dec^–1) as well as a satisfactory long-time stability. Electrochemical studies reveal that this hierarchical structure facilitates a full exposure of active sites and facile ion transport kinetics, accounting for the excellent performance. It is expected that the NiFe-LDH microsphere material can serve as a promising non-noble-metal-based electrocatalyst toward water oxidation reaction

LiCoO₂ Ultrathin Layer for Uniform Lithium Deposition toward a Highly Stable Lithium Metal Anode

Electricity produced from renewable energy sources should be stored in energy storage devices efficiently due to large fluctuations in generation. The lithium metal battery is one of the most promising energy storage devices due to its high energy densities. However, continuous dendrite growth and huge volumetric changes of the lithium metal anode have hindered practical applications. Herein, we demonstrate a strategy to fabricate a dendrite-free Li metal anode by an ultrathin LiCoO2 layered modified conductive carbon cloth (CC) substrate (CC/LCO-UTF), where LiCoO2, serving as a stable lithiophilic interface, enables a uniform nucleation and dendrite-free growth of the metal Li. As a result, a stable cycling performance over 1960 h with a lower overpotential of ∼20 mV is achieved at a current density of 2 mA cm–2, which is superior to the most recent reports. Moreover, the assembled Li||LFP and Li||S full cells with the CC/LCO-UTF@Li anode deliver a superior electrochemical performance. These findings are expected to provide a new strategy to design an advanced dendrite-free Li metal anode toward future high-performance Li metal batteries

LiCoO₂ Ultrathin Layer for Uniform Lithium Deposition toward a Highly Stable Lithium Metal Anode

Electricity produced from renewable energy sources should be stored in energy storage devices efficiently due to large fluctuations in generation. The lithium metal battery is one of the most promising energy storage devices due to its high energy densities. However, continuous dendrite growth and huge volumetric changes of the lithium metal anode have hindered practical applications. Herein, we demonstrate a strategy to fabricate a dendrite-free Li metal anode by an ultrathin LiCoO2 layered modified conductive carbon cloth (CC) substrate (CC/LCO-UTF), where LiCoO2, serving as a stable lithiophilic interface, enables a uniform nucleation and dendrite-free growth of the metal Li. As a result, a stable cycling performance over 1960 h with a lower overpotential of ∼20 mV is achieved at a current density of 2 mA cm–2, which is superior to the most recent reports. Moreover, the assembled Li||LFP and Li||S full cells with the CC/LCO-UTF@Li anode deliver a superior electrochemical performance. These findings are expected to provide a new strategy to design an advanced dendrite-free Li metal anode toward future high-performance Li metal batteries

LiCoO₂ Ultrathin Layer for Uniform Lithium Deposition toward a Highly Stable Lithium Metal Anode

Electricity produced from renewable energy sources should be stored in energy storage devices efficiently due to large fluctuations in generation. The lithium metal battery is one of the most promising energy storage devices due to its high energy densities. However, continuous dendrite growth and huge volumetric changes of the lithium metal anode have hindered practical applications. Herein, we demonstrate a strategy to fabricate a dendrite-free Li metal anode by an ultrathin LiCoO2 layered modified conductive carbon cloth (CC) substrate (CC/LCO-UTF), where LiCoO2, serving as a stable lithiophilic interface, enables a uniform nucleation and dendrite-free growth of the metal Li. As a result, a stable cycling performance over 1960 h with a lower overpotential of ∼20 mV is achieved at a current density of 2 mA cm–2, which is superior to the most recent reports. Moreover, the assembled Li||LFP and Li||S full cells with the CC/LCO-UTF@Li anode deliver a superior electrochemical performance. These findings are expected to provide a new strategy to design an advanced dendrite-free Li metal anode toward future high-performance Li metal batteries

Photoassisted Strategy to Promote Glycerol Electrooxidation to Lactic Acid Coupled with Hydrogen Production

Electrocatalytic oxidation of glycerol (GLY; from a biodiesel byproduct) to lactic acid (LA; the key monomers for polylactic acid; PLA) is considered a sustainable approach for biomass waste upcycling and is coupled with cathodic hydrogen (H2) production. However, current research still suffer from issues of low current density and low LA selectivity. Herein, we reported a photoassisted electrocatalytic strategy to achieve the selective oxidation of GLY to LA over a gold nanowire (Au NW) catalyst, attaining a high current density of 387 mA cm–2 at 0.95 V vs RHE, together with a high LA selectivity of 80%, outperforming most of the reported works in the literature. We reveal that the light-assistance strategy plays a dual role, which can both accelerate the reaction rate through the photothermal effect and also promote the adsorption of the middle hydroxyl of GLY over Au NWs to realize the selective oxidation of GLY to LA. As a proof-of-concept, we realized the direct conversion of crude GLY that was extracted from cooking oil to attain LA and coupled it with H2 production using the developed photoassisted electrooxidation process, revealing the potential of this strategy in practical applications