Porous LaFeO3 nanofiber with oxygen vacancies as an efficient electrocatalyst for N2 conversion to NH3 under ambient conditions

Electrocatalytic N2 reduction to NH3 under ambient conditions is an eco-friendly and sustainable alternative to the traditional Haber-Bosch process. However, inhibited by the high activation barrier of N2, this process needs efficient electrocatalysts to adsorb and activate the N2, enabling the N2 reduction reaction(NRR). Herein, we report that porous LaFeO3 nanofiber with oxygen vacancies acts as an efficient NRR electrocatalyst with abundant active sites to enhance the adsorption and activation of N2. When tested in 0.1 M HCl, such electrocatalyst achieves a high Faradaic efficiency of 8.77% and a large NH3 yield rate of 18.59 μg h–1 mgcat–1.at-0.55 V versus reversible hydrogen electrode. This catalyst also shows high long-term electrochemical stability and excellent selectivity for NH3 formation. Density functional theory calculations reveal that, by introducing oxygen vacancy on LaFeO3, the subsurface metallic ions are exposed with newly localized electronic states near the Fermi level, which facilitates the adsorption and activation of N2 molecules as well as the subsequent hydrogenation reactions.

In-situ assembly of 2D/3D porous nickel cobalt sulfide solid solution as superior pre-catalysts to boost multi-functional electrocatalytic oxidation

In this work,we fabricated an efficient pre-catalyst based on(Ni,Co)S2solid solution with hierarchical architecture and high porosity to boost urea oxidation reaction and electrocatalytic oxidation of organic small molecules.The interaction between Ni and Co can optimize the electronic structure,resulting in the improved conductivity and accelerated charge transfer rate.The 2D/3D architecture can enrich more active species and endow the mass and electron transport to facilitate the surface oxidation and the following catalytic process.Post-structure and catalytic characterizations confirm the surface oxidation of(Ni,Co)S_(2)during the stability test,and the in-situ formed Co(Ni)based(oxy)hydroxides exhibit superior catalytic activity and facilitated charge transfer ability.As a result,the optimal(Ni,Co)S_(2)solid solution pre-catalyst displays facilitated catalytic behavior and good stability for multifunctional electrocatalytic oxidation,in which a high conversion of benzyl alcohol(97.50%),a good selectivity to benzoic acid(93.78%)and a satisfied faraday efficiency(91.86%)can be achieved.

Defect-rich MoS2 nanowall catalyst for efficient hydrogen evolution reaction

Designing efficient electrocatalysts for the hydrogen evolution reaction （HER） has attracted substantial attention owing to the urgent demand for clean energy to face the energy crisis and subsequent environmental issues in the near future. Among the large variety of HER catalysts, molybdenum disulfide （MoS2） has been regarded as the most famous catalyst owing to its abundance, low price, high efficiency, and definite catalytic mechanism. In this study, defect-engineered MoS2 nanowall （NW） catalysts with controllable thickness were fabricated and exhibited a significantly enhanced HER performance. Benefiting from the highly exposed active edge sites and the rough surface accompanied by the robust NW structure, the defect-rich MoS2 NW catalyst with an optimized thickness showed an ultralow onset overpotential of 85 mV, a high current density of 310.6 mA·cm^-2 at η = 300 mV, and a low potential of 95 mV to drive a 10 mA·cm^-2 cathodic current. Additionally, excellent electrochemical stability was realized, making this freestanding NW catalyst a promising candidate for practical water splitting and hydrogen production.

Hexagonal boron nitride nanosheet for effective ambient N2 fixation to NH3

Industrial production of NH3 from N2 and H2 significantly relies on Haber-Bosch process,which suffers from high energy consume and CO2 emission.As a sustainable and environmentally-benign alternative process,electrochemical artificial N2 fixation at ambient conditions,however,is highly required efficient electrocatalysts.In this study,we demonstrate that hexagonal boron nitride nanosheet (h-BNNS) is able to electrochemically catalyze N2 to NH3.In acidic solution,h-BNNS catalyst attains a high NH3 formation rate of 22.4 μg·h-1·mg-1cat.and a high Faradic efficiency of 4.7% at-0.75 V vs.reversible hydrogen electrode,with excellent stability and durability.Density functional theory calculations reveal that unsaturated boron at the edge site can activate inert N2 molecule and significantly reduce the energy barrier for NH3 fonmation.

Ni(OH)_(2) nanoparticles encapsulated in conductive nanowire array for high-performance alkaline seawater oxidation

Design and development of high-efficiency and durable oxygen evolution reaction(OER)electrocatalysts is crucial for hydrogen production from seawater splitting.Herein,we report the in situ electrochemical conversion of a nanoarray of Ni(TCNQ)2(TCNQ=tetracyanoquinodimethane)on graphite paper into Ni(OH)_(2) nanoparticles confined in a conductive TCNQ nanoarray(Ni(OH)_(2)-TCNQ/GP)by anode oxidation.The Ni(OH)_(2)-TCNQ/GP exhibits high OER performance and demands overpotentials of 340 and 382 mV to deliver 100 mA·cm^(−2) in alkaline freshwater and alkaline seawater,respectively.Meanwhile,the Ni(OH)_(2)-TCNQ/GP also demonstrates steady long-term electrochemical durability for at least 80 h under alkaline seawater.

N-doped carbon nanotubes supported CoSe_(2) nanoparticles:A highly efficient and stable catalyst for H_(2)O_(2) electrosynthesis in acidic media

Electrocatalytic oxygen reduction reaction(ORR)provides an attractive alternative to anthraquinone process for H_(2)O_(2) synthesis.Rational design of earth-abundant electrocatalysts for H_(2)O_(2) synthesis via a two-electron ORR process in acids is attractive but still:very challenging.In this work,we report that nitrogen-doped carbon nanotubes as a multi-functional support for CoSe2 nanoparticles not only keep CoSe_(2) nanoparticles well dispersed but alter the crystal structure,which in turn improves the overall catalYtic behaviors and thereby renders high O_(2)-to-H_(2)O_(2) conversion efficiency.In 0.1 M HClO_(4),such CoSe_(2)@NCNTs hybrid delivers a high H_(2)O_(2) selectivity of 93.2% and a large H_(2)0_(2) yield rate of 172 ppm·h^(-1) with excellent durability up to 24 h.Moreover,CoSe_(2)@NCNTs performs effectively for organic dye degradation via electro-Fenton process.

Removal of toxic metal ions using chitosan coated carbon nanotube composites for supercapacitors

Environmental pollution and energy crisis are two major global challenges to human beings.Recovering energy from wastewater is considered to be one of the effective approaches to address these two issues synchronously.As the main pollutants in wastewater,toxic heavy metal ions are the potential candidates for energy storage devices with pseudocapacitive behaviors.In this study,toxic metal ions of Cr(VI)and Cu(II)are removed efficiently by chitosan coated oxygen-containing functional carbon nanotubes,and the corresponding equilibrium adsorption capacity is 142.1 and 123.7 mg g^(-1).Followed by carbonization of metal ions-adsorbed adsorbents,Cu-and Cr N-loaded carbon composites can be obtained.Electrochemical measurements show that the supercapacitor electrodes based on Cu-and Cr N-loaded carbon composites have specific capacitance of 144.9 and 114.9 F g^(-1)at2 m V s^(-1),with superior electrochemical properties to pure chitosan coated carbon nanotubes after carbonization.This work demonstrates a new strategy for the resource-utilization of other heavy metal ions for energy devices,and also provides a new way to turn environmental pollutants into clean energy.

High Performance Supercapacitors from Hierarchical Porous Carbon Aerogels Based on Sliced Bread

Supercapacitor electrodes with porous structure based on renewable,eco-friendly and cost-effective materials have caused extensive concern in energy storage fields.Sliced bread,the common food ingredient,mainly containing glucose polymers,can be a promising candidate to fabricate porous supercapacitor electrodes.Highly porous carbon aerogels by using sliced bread as the raw material were synthesized through a carefully controlled aerogel carbonization-activation process.Interestingly,the specific surface area and the pore size distribution of the porous carbon were controlled by the activation temperature,which result in the varied performance of the carbon aerogel as a supercapacitor.Electrochemical investigation measurements revealed that the hierarchical porous carbon aerogel shows an excellent capacitor behavior for construction of a symmetric supercapacitor,which demonstrated a high specific capacitance of 229 F·g-1 at discharge current of 0.2 A·g-1.In addition,the fabricated supercapacitor displayed excellent capacitance retention of 95.5% over 5000 cycles.

Benzoate anions-intercalated NiFe-layered double hydroxide nanosheet array with enhanced stability for electrochemical seawater oxidation

Seawater electrolysis is an extremely attractive approach for harvesting clean hydrogen energy,but detrimental chlorine species(i.e.,chloride and hypochlorite)cause severe corrosion at the anode.Here,we report our recent finding that benzoate anions-intercalated NiFe-layered double hydroxide nanosheet on carbon cloth(BZ-NiFe-LDH/CC)behaves as a highly efficient and durable monolithic catalyst for alkaline seawater oxidation,affords enlarged interlayer spacing of LDH,inhibits chlorine(electro)chemistry,and alleviates local pH drop of the electrode.It only needs an overpotential of 320 mV to reach a current density of 500 mA·cm^(−2)in 1 M KOH.In contrast to the fast activity decay of NiFe-LDH/CC counterpart during long-term electrolysis,BZ-NiFe-LDH/CC achieves stable 100-h electrolysis at an industrial-level current density of 500 mA·cm^(−2)in alkaline seawater.Operando Raman spectroscopy studies further identify structural changes of disorderedδ(NiIII-O)during the seawater oxidation process.