KOH Electrolyte Solution Research Articles

Electrochemical exploration on hexadecylamine capped copper sulfide nanocubes using single source precursor for enhanced supercapacitor devices

Copper sulfide (CuS) based material has been broadly used in recent years because of its semiconducting and non-toxic nature. CuS nanocubes (NCs) were synthesized at low temperature by the solvothermal method using copper diethyldithiocarbamate (Cu[DTC]2) as a single-source precursor and the presence of hexadecylamine (HDA) as shape directing agent. As-prepared CuS NCs properties like thermal, phase, vibrational group, morphology and elemental were explored by different analytic tools. Further, the electrochemical behaviours of CuS NCs modified working electrode were examined in 1 M KOH electrolyte solution. It exhibits remarkable specific capacitance (Csp) of 1472.3 Fg−1 at 1 Ag−1 with excellent capacitive retention up to 93.6 % after 5000 charge-discharge cycles at the current density of 10 Ag−1. Besides, the two electrode asymmetric supercapacitor (ASC) device was constructed and it exhibits the Csp of 54 Fg−1 at 3 Ag−1. Moreover, even after 5000 cycles at a 7 Ag−1 of current density, the ASC device was able to retain internal capacitance retention of 91.2 % due to its high energy density of 21.68 Wh kg−1 and power density of 1272.92 W kg−1. After 5000 cycle's electrochemical evaluation of CuS NCs modified electrode were analyzed. These outcomes of electrochemical performance suggested that fabricated CuS||AC device has a bright future in energy storage application.

A facile and almost HF-free synthesis of Ti3C2@CuCl composite for supercapacitors

This work demonstrates a distinctive almost HF-free route of etching Ti3AlC2 MAX phase by metal displacement reaction at room temperature. The Ti3AlC2 particles are directly etched by CuCl2 solutions in different concentrations instead of HF. The etchant is reduced to nano CuCl particles, adhering to the surface of Ti3C2 layers to form the Ti3C2@CuCl composite which is evaluated as working electrodes for supercapacitors. Due to the synergistic effect between CuCl and Ti3C2 matrix, the appropriate amount of CuCl enhances the specific capacitance to 508.7 F·g−1 at 1A·g−1 in 6 M KOH electrolyte solution, which is much higher than pure Ti3C2 electrode. This work shows the possibility of synthesis of various Mxene-based frameworks by other metallic cations with lower metal activity.

Ag nanoparticles synthesized by Datura metel L. Leaf extract and their charge density distribution, electrochemical and biological performance

The present study investigates the electrochemical performance; charge density distribution, antimicrobial and antifungal activities of green synthesized silver nanoparticles (Ag NPs) using the leaf extract of Datura metel L. UV–vis absorption spectrum shows that highly stable, monodispersed Ag NPs formed at 418 nm. Particle size analysis with zeta potential values 117 nm, − 27.3 mV are implied that hydrodynamic size with negative surface charges. Fourier transforms infrared (FTIR) analysis identified amide functional groups in Datura metel L. responsible for the reduction and stabilization of nanoparticles. Scanning electron microscopy (SEM) analysis showed about the spherical morphology and Energy Dispersive Absorption X-ray (EDAX) spectrum displays the Ag peak at 3.1 KeV with encapsulation of organic trace elements. X-ray Photoelectron Spectroscopy (XPS) analysis exhibit’s Ag 3d, Ag 3p, and Ag 3s chemical state of Ag NPs and the X-ray Diffraction (XRD) pattern confirmed the crystalline nature at 38.1˚ with organometallic phases. The structure factors in the single unit cells are studied in about three, two, and one-dimensional profiles using the Rietveld refinement technique. The complex of atropine with the nanoparticle was modeled using the MOPS method. The formation of the complex is carried out due to the transfer of the electron density of Ag NPs to the atropine molecule, which consists of more electronegative atoms. A charge transfer complex in which the nanoparticle acquires a charge of +0.354 and the atropine – 0.354 is formed. The synthesized Ag NPs exhibited noticeable antimicrobial, antifungal activity with large–diameter inhibition zones against S. pyogenes (12.1 ± 0.66 mm), E. faecalis (11.8 ± 0.33 mm), K. pneumoniae (10.2 ± 0.44 mm), S. flexneri (10.3 ± 0.21 mm), C. albicans (11.3 ± 0.66 mm), and A. fumigatus (10.5 ± 0.33 mm). The green synthesized Ag NPs as prepared electrode exhibits specific capacitance of 825 F/g at the current density of 3 mA/g in 1 M KOH electrolyte solution and cyclic stability retained at about 88.35% even after 5000 cycles with the current density of 5 mA/g. The results showed their effective utilization of green synthesized Ag NPs in biological and electrochemical storage applications.

Hierarchical Fe2O3 hexagonal nanoplatelets anchored on SnO2 nanofibers for high-performance asymmetric supercapacitor device

Metal oxide heterostructures have gained huge attention in the energy storage applications due to their outstanding properties compared to pristine metal oxides. Herein, magnetic Fe2O3@SnO2 heterostructures were synthesized by the sol–gel electrospinning method at calcination temperatures of 450 and 600 °C. XRD line profile analysis indicated that fraction of tetragonal tin oxide phase compared to rhombohedral hematite was enhanced by increasing calcination temperature. FESEM images revealed that hexagonal nanoplatelets of Fe2O3 were hierarchically anchored on SnO2 hollow nanofibers. Optical band gap of heterogeneous structures was increased from 2.06 to 2.40 eV by calcination process. Vibrating sample magnetometer analysis demonstrated that increasing calcination temperature of the samples reduces saturation magnetization from 2.32 to 0.92 emu g-1. The Fe2O3@SnO2-450 and Fe2O3@SnO2-600 nanofibers as active materials coated onto Ni foams (NF) and their electrochemical performance were evaluated in three and two-electrode configurations in 3 M KOH electrolyte solution. Fe2O3@SnO2-600/NF electrode exhibits a high specific capacitance of 562.3 F g-1 at a current density of 1 A g-1 and good cycling stability with 92.8% capacitance retention at a high current density of 10 A g-1 after 3000 cycles in three-electrode system. The assembled Fe2O3@SnO2-600//activated carbon asymmetric supercapacitor device delivers a maximum energy density of 50.2 Wh kg-1 at a power density of 650 W kg-1. The results display that the Fe2O3@SnO2-600 can be a promising electrode material in supercapacitor applications.

Facile preparation of SnO2/MoS2 nanocomposites with high electrochemical performance for energy storage applications

• SnO 2 /MoS 2 nanocomposite was synthesized by Sonochemical method. • The crystallite size of SnO 2 /MoS 2 nanocomposites was reduced while increasing the percentage of MoS 2 . • The FESEM images confirm the spherical morphology of SnO 2 and flake-like morphology of MoS 2 . • SnO 2 /MoS 2 (5 wt%) nanocomposite exhibited higher specific capacitance of 146F/g at a current density of 1 A/g. • High specific capacitance of composite is due to the synergetic effect of SnO 2 and MoS 2 . In this article, the pristine SnO 2 nanoparticles and MoS 2 nanoflakes were synthesized by the hydrothermal method. SnO 2 /MoS 2 nanocomposite is prepared by sonochemical method and the weight percent of MoS 2 is 1 %, 2 %, and 5 % in the composite. The Physicochemical properties such as the structural, morphological, optical properties, and functional groups of pristine SnO 2 and MoS 2 were analyzed and compared with SnO 2 /MoS 2 nanocomposites. XRD patterns confirmed the formation of cassiterite rutile SnO 2 with tetragonal structure. The lattice strain and crystallite size were calculated by Size-Strain plot method (SSP).The presence of functional groups was confirmed by FTIR analyses. The absorption and the bandgap of samples were found using the DRS UV–vis spectrum. Morphology, elemental composition, and particle size of the prepared samples were analyzed by FESEM, EDAX, and HRTEM. The BET analysis reveals the Surface area and pore volume of synthesized SnO2/MoS2 nanocomposite was relatively higher than the SnO 2 nanoparticles. The electrochemical performance of the prepared electrodes was evaluated by Chronopotentiometry (CP), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) analysis. The 5 % SnO 2 /MoS 2 composite electrode shows a maximum specific capacitance of 146F/g in a 2 M KOH electrolyte solution at a current density of 1 A/g.

Metal–Organic Framework-Derived 2D NiCoP Nanoflakes from Layered Double Hydroxide Nanosheets for Efficient Electrocatalytic Water Splitting at High Current Densities

Two-dimensional (2D) metal–organic framework (MOF)-derived NiCoP nanoflakes, denoted as NiCo(nf)-P, are prepared via in situ growth of MOF using NiCo layered double hydroxide (LDH) as a sacrificial template, followed by phosphorization. The nanoparticle-decorated 2D nanoflake morphology and the intrinsic porosity inherited from the MOF precursor render NiCo(nf)-P a highly efficient bifunctional electrocatalyst toward hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting. In 1.0 M KOH electrolyte solution, NiCo(nf)-P shows low overpotentials of 199/283/317 and 315/378/416 mV at 100/500/1000 mA cm–2 for HER and OER, respectively. For overall water splitting, it only needs low cell voltages of 1.74/1.86/1.94 V to reach 100/500/1000 mA cm–2, with outstanding long-term stability over 30 h. The excellent catalytic performance of NiCo(nf)-P outperforms most of the NiCoP-based electrocatalysts reported so far, indicating its great potential for the overall water splitting application.

A novel NiCo2S4-based capacitive material with a homogeneous and heteromorphic construction

Aim to improve the capacitive performance of the NiCo2S4-based electrode materials, a novel composite material with a homogeneous and heteromorphic construction, h-NiCo2S4/u-NiCo2S4/NF, was successfully prepared through layer-by-layer growth in a hydrothermal process using urea and hexamethylenetetramine as alkali source in this work. This material presents a specific capacity high up to 1245.3 C g−1 (345.9 mAh g−1) at the current density of 2 A g−1 in a 6 M KOH electrolyte solution. Moreover, a 74.6 % of the initial specific capacity is still retained when the current density increases from 2 to 10 A g−1, showing a relatively good rate capability. Especially, an 84.0 % of capacity retention rate can be obtained after it suffers from 7000 charging-discharging cycles at 50 mA cm−2 (9.2 A g−1), exhibiting a good cycling stability. Using it as the positive electrode material to assemble an asymmetrical supercapacitive device with a home-made porous carbon (PC) as the negative electrode material, an energy density high up to 48.4 Wh kg−1 at 1060.6 W kg−1 and a 63.2 % of capacity retention rate at 10,000 charging-discharging cycles can be achieved, superior to many NiCo2S4-based asymmetrical supercapacitive devices reported so far.

Ultrasound-assisted synthesis of nickel/nickel phosphide on carbon nanotubes as highly effective electrocatalysts for hydrogen evolution reaction in alkaline solution

Nickel phosphides are considered to be excellent non-noble metal electrocatalysts for hydrogen evolution reaction (HER). However, the HER activity of nickel phosphides is still not ideal due to their relatively weak electrical conductivity. The HER performance can be enhanced by combining nickel phosphides with highly conductive materials. Here, nickel and nickel phosphide nanoparticles supported on pristine carbon nanotubes (Ni-Ni12P5/CNTs) were prepared through an ultrasonic electroless plating method. The combination of Ni-Ni12P5 active sites and the CNTs with good conductivity made the Ni-Ni12P5/CNTs good HER electrocatalytic performance with an overpotential of 120 mV at 10 mA cm−2 and a Tafel slope of 53 mV dec−1. Coupled with the outstanding chemical stability of CNTs and their strong chemical bonds with Ni-Ni12P5, the Ni-Ni12P5/CNTs electrocatalyst possessed good stability in 0.1 M KOH electrolyte solution. The ultrasonic electroless plating offers a new way for facile designing of transition metal composites with improving electrocatalytic performance toward HER.

Bismuth oxide-doped graphene-oxide nanocomposite electrode for energy storage application

Nanocrystalline and porous bismuth oxide-doped graphene oxide nanocomposite (Bi2O3-GO NC) electrode material synthesized via microwave irradiation method has been envisaged for supercapacitor application. Surface morphology, elemental configuration, phase purity, surface area, porosity, and binding energy etc., are initially screened and then preferred in electrochemical measurement analysis. The as-obtained Bi2O3–GO NC electrode adduces a better performance with quasi-faradaic redox reactions in electrochemical measurements over pristine GO in 6 M KOH electrolyte solution. The specific capacitance of the Bi2O3–GO NC electrode measured at current densities 5–14 A/g is varied from 1250 to 933 F/g. The as-assembled Bi2O3–GO//Bi2O3–GO symmetric supercapacitor device reveals an exceptional electrochemical performance with 25.83 W-h/kg specific energy at 337 W/kg specific power, and excellent stability of about 80% for 5000 cycles, evidencing usability potential of metal oxide-GO composite electrode materials over solitary carbonaceous electrode. A demonstration of 42 LEDs ignited with full-bright intensity supports our claim as well.

NiCo-BDC derived Co3+ enriched NiCoxOy/NF nanosheets for oxygen evolution reaction

In recent years, transition metal catalysts due to their low price, excellent conductivity and high activity have been extensively studied in OER. It is worth noting that Co3+ plays a vital role in the process of oxygen evolution catalysis, because Co3+ ions are considered to be active sites. The development of catalysts with high Co3+ content has important application prospects for improving water oxidation efficiency. This paper uses a simple ligand-assisted synthesis method to promote the transformation of two-dimensional layered double hydroxides (LDHs) into two-dimensional metal organic frameworks (MOFs). MOF-OH/NF are quickly and easily prepared by electrooxidation, which exhibit superior OER properties, with a low overpotential of 260 mV and 420 mV for the oxygen evolution reaction (OER) at 100 mA cm−2 and 1000 mA cm−2. Moreover, the MOF-OH/NF has good stability in 1.0 M KOH electrolyte solution. This study provides a new idea for the design and synthesis of novel composite electrocatalysts.

RETRACTED: Oxygen vacancy induced high specific capacitance in Sr2CoSbO6

Sr2CoSbO6, a double perovskite compound known to have oxide ion vacancies, is not well explored for its electrical properties. In the present article, we study the effect of the aliovalent doping of Na+ at Sr site in Sr2CoSbO6 on their electrochemical performance. The X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) techniques confirm the phase formation and reveal particle-like morphologies for all the samples. The cyclic voltammetry study reveals the specific capacitance increases with increasing Na concentration and a specific capacitance value of 228 F/g is obtained for the maximum dopant composition. Excellent cycling stability of 92% of initial capacitance retention even after 2000 continuous cycles at a high scan rate of 100 mVs-1 in an aqueous 1 M KOH electrolyte solution and a 98% of coulombic efficiency at a current density of 1 A/g is observed. These values suggest that the Na doped Sr2CoSbO6 can find application as supercapacitors material.

Self-assembled Zn-functionalized Ni-MOF as an efficient electrode for electrochemical energy storage

Zinc-functionalized nickel metal-organic framework (Zn/Ni-MOF) was grown directly on nickel foam (NF) and used as an efficient binder-free electrode for supercapacitor application. The structural characteristics of the composite materials were analyzed by different analytical techniques. The results obtained revealed flower-decorated ball-shape microstructures were obtained from Zn functionalization of the surface of Ni-MOF microsheets, with a relatively larger surface area and unique pore characteristics. The electrochemical performance measured using a 3 M KOH electrolyte solution indicated that Zn-doped Ni-MOF containing Zn/Ni in the ratio 1:2 (ZNN1) exhibited the optimum performance. ZNN1 revealed good rate capability with a maximum specific capacitance of 391 Fg-1 at a current density of 1 Ag-1 and retained about 70% of its initial capacitance at 10 Ag-1. The electrode also possessed maximum energy and power density of 12 Wh kg−1 and 2000 Wkg-1, respectively, with a high cycling stability of 85% after 5000 cycles. The enhanced electrochemical performance of ZNN1 was attributed to the increase in the surface area and electrical conductivity of Ni-MOF occasioned by incorporation of an optimum concentration of Zn dopant. The charge storage mechanism was predominantly controlled by the diffusion process, which suggests that the method employed in this study is promising for the fabrication of pseudocapacitive materials.

One-Dimensional Nanoscale Si/Co Based on Layered Double Hydroxides towards Electrochemical Supercapacitor Electrodes.

It is well known that layered double hydroxides (LDHs) are two-dimensional (2D) layered compounds. However, we modified these 2D layered compounds to become one-dimensional (1D) nanostructures destined for high-performance supercapacitors applications. In this direction, silicon was inserted inside the nanolayers of Co-LDHs producing nanofibers of Si/Co LDHs through the intercalation of cyanate anions as pillars for building nanolayered structures. Additionally, nanoparticles were observed by controlling the preparation conditions and the silicon percentage. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermal analyses have been used to characterize the nanolayered structures of Si/Co LDHs. The electrochemical characterization was performed by cyclic voltammetry and galvanic charge–discharge technique in 2M KOH electrolyte solution using three-electrode cell system. The calculated specific capacitance results indicated that the change of morphology from nanoparticles or plates to nanofibers had a positive effect for improving the performance of specific capacitance of Si/Co LDHs. The specific capacitance enhanced to be 621.5 F g−1 in the case of the nanofiber of Si/Co LDHs. Similarly, the excellent cyclic stability (84.5%) was observed for the nanofiber. These results were explained through the attribute of the nanofibrous morphology and synergistic effects between the electric double layer capacitive character of the silicon and the pseudo capacitance nature of the cobalt. The high capacitance of ternary Si/Co/cyanate LDHs nanocomposites was suggested to be used as active electrode materials for high-performance supercapacitors applications.

Rhenium Sulfide Incorporated in Molybdenum Sulfide Nanosheets for High-Performance Symmetric Supercapacitors with Enhanced Capacitance.

Supercapacitors are considered potential energy storage devices and have drawn significant attention due to their superior intrinsic advantages. Herein, we report the synthesis of ReS2 embedded in MoS2 nanosheets (RMS-31) by a hydrothermal technique. The prepared RMS-31 electrode material demonstrated superior pseudocapacitive behavior in 1 M KOH electrolyte solution, which is confirmed by the heterostructure of RMS-31 nanosheet architectures. RMS-31 has a specific capacitance of 244 F g-1 at a current density of 1 A g-1 and a greater areal capacitance of 540 mF cm-2 at a current density of 5 mA cm-2. The symmetric supercapacitor device with the RMS-31 electrode delivers an energy density of 28 W h cm-2 with a power density of 1 W cm-2 and reveals long-term stability at a constant current density of 5 mA cm-2 for 10,000 cycles while accomplishing a retention of 66.5%. The high performance of this symmetric device is attributed to the synergistic effect of ReS2 and MoS2 and the presence of the metallic 1T-MoS2 phase in the RMS-31 electrode. To the best of our knowledge, this is the first report of increasing the interlayer spacing of 2H-MoS2 by incorporating ReS2 for symmetric supercapacitor applications.

Pseudocapacitivebehavior of coin-like NiO/r-GO nanocomposites as an efficient electrode material for energy storage application

ABSTRACT Herein, a novel coin like NiO/r-GO nanocomposite was synthesised by the facial hydrothermal method. The prepared materials were used as an anode material for supercapacitors in the aqueous KOH electrolyte solution. The phase purity and crystal structure, morphology, chemical composition, chemical oxidation state of the prepared samples were studied by Powder XRD, FE-SEM with elemental mapping, TEM, and XPS techniques.The FE-SEM and TEM analysis of NiO/r-GO composite possesses a coin-like NiO morphology with covered r-GO nanosheets and an average size of 200 ± 50 nm. The prepared NiO/r-GO nanocomposite electrode material exhibits a high specific capacity of 115Cg−1 at 0.5 Ag−1, which is high rate capability, and stable GCD cycling performance (98% retention after 5000 successive charge-discharge cycles at 10 Ag−1).

A Facile Etching Route for Preparing Ti3C2 MXene with Enhanced Electrochemical Performance in Silver Nitrate Solution

Two-dimensional Ti3C2 MXene is a promising electrode material for high-capacity supercapacitor, which is normally prepared by selective etching of the Al layer from ternary carbide Ti3AlC2 MAX phase using HF acid solution. Here a distinct etching method using a little HF acid is reported. Ti3C2 MXene decorated with Ag nanoparticles are synthesized via a chemical replacement reaction with AgNO3 solution at room temperature and then evaluated as working electrodes. Due to the synergistic effect between Ag and Ti3C2 matrix, the resulting composite of the 10 wt% AgNO3 treated sample (Ag-10) exhibits higher specific capacitance of 779.5 F g−1 at the scan rate of 5 mV s−1 in 6 M KOH electrolyte solution and shows good cycling stability with capacitance retaining 95% after 5000-cycles. This work also shows the possibility of using other metallic cations with higher redox potential to prepare high performance MXenes for supercapacitor materials.

TiO2 nanorods decorated on RGO sheet for an excellent energy storage performance

Herein, we report nanocomposite of titanium dioxide (TiO2) nanorods decorated reduced graphene oxide (TiO2/RGO) nanocomposite prepared using the simple, one-pot hydrothermal route for electrode material in supercapacitor applications. A systematic comparison study was carried out for the TiO2 nanorods coated on graphite foil in presence of alkaline media 3 M KOH, NaCl, and Na2SO4 using the three-electrode method. The TiO2/RGO composite shows an excellent specific capacitance (Csp) of 330 Fg-1 at the discharge current density 0.5 Ag-1 in presence of 3 M KOH electrolyte solution. The obtained highest specific capacitance values in order by various electrolytes are observed as KOH > NaCl > Na2SO4. The long-term cycle stability of charge and discharge cycle at current density 0.5 Ag-1 over 1000 cycles and only 8% decay in the specific capacitance of TiO2/RGO nanocomposite was observed in 3 M KOH electrolyte. The improved electrochemical performance TiO2/RGOcomposite in presence of KOH electrolyte is shown to be the most suitable electrode for the supercapacitors.

Catalytic Properties of Free-Base Porphyrin Modified Graphite Electrodes for Electrochemical Water Splitting in Alkaline Medium

Hydrogen generation via electrochemical water splitting is considered an eco-friendly pathway for obtaining this desired alternative energy source, and it has triggered an intensive search for low cost and efficient catalysts. Within this context, four free-base porphyrins were studied as heterogeneous catalysts for the oxygen and hydrogen evolution reactions (OER and HER) in alkaline aqueous solutions. TEM and STEM analyses of samples obtained by drop-casting the porphyrins from different organic solvents on TEM grids revealed a rich variety of aggregates due to the self-assembling property of the porphyrin molecules. Modified electrodes were manufactured by applying the four tetrapyrrolic macrocycles from various solvents on the surface of graphite supports, in one or more layers. Experiments performed in 0.1 M and 1 M KOH electrolyte solutions allowed the identification of the most electrocatalytically active electrodes for the OER and HER, respectively. In the first case, the electrode was manufactured by applying three layers of 5-(4-pyridyl)-10,15,20-tris(4-phenoxyphenyl)porphyrin on the graphite substrate from N,N-dimethylformamide solution was identified as overall catalytically superior. In the second case, the electrode obtained by applying one layer of 5,10,15,20-tetrakis(4-allyloxyphenyl)-porphyrin from benzonitrile solution displayed an HER overpotential value of 500 mV at i = −10 mA/cm2 and a Tafel slope of 190 mV/dec.

Sm0.5Sr0.5Co1-xNixO3-δ-A Novel Bifunctional Electrocatalyst for Oxygen Reduction/Evolution Reactions.

The development of non-precious metal catalysts with excellent bifunctional activities is significant for air–metal batteries. ABO3-type perovskite oxides can improve their catalytic activity and electronic conductivity by doping transition metal elements at B sites. Here, we develop a novel Sm0.5Sr0.5Co1−xNixO3−δ (SSCN) nanofiber-structured electrocatalyst. In 0.1 M KOH electrolyte solution, Sm0.5Sr0.5Co0.8Ni0.2O3−δ (SSCN82) with the optimal Co: Ni molar ratio exhibits good electrocatalytic activity for OER/ORR, affording a low onset potential of 1.39 V, a slight Tafel slope of 123.8 mV dec−1, and a current density of 6.01 mA cm−2 at 1.8 V, and the ORR reaction process was four-electron reaction pathway. Combining the morphological characteristic of SSCN nanofibers with the synergistic effect of cobalt and nickel with a suitable molar ratio is beneficial to improving the catalytic activity of SSCN perovskite oxides. SSCN82 exhibits good bi-functional catalytic performance and electrochemical double-layer capacitance.

The Spin Modulation Stimulated Efficient Electrocatalytic Oxygen Evolution Reaction over LaCoO3 Perovskite.

Perovskite is a promising non-noble catalyst and has been widely investigated for the electrochemical oxygen evolution reaction (OER). However, there is still serious lack of valid approaches to further enhance their catalytic performance. Herein, we propose a spin state modulation strategy to improve the OER electrocatalytic activity of typical perovskite material of LaCoO3 . Specifically, the electronic configuration transition was realized by a simple high temperature thermal reduction process. M-H hysteresis loop results reveal that the reduction treatment can produce more unpaired electrons in 3d orbit by promoting the electron transitions of Co from low spin state to high spin state, and thus lead to the increase of the spin polarization. Electrochemical measurements show that the catalytic performance of LaCoO3 is strongly dependent on its electronic configuration. With the optimized reduction treatment, the overpotential for the OER process in 0.5 M KOH electrolyte solution at 10 mA cm-2 current density was 396 mV, significantly lower than that of the original state. Furthermore, it can mediate efficient OER with an overpotential of 383 mV under an external magnetic field, which is attributed to the appropriate electron filling. Our results show that electron spin state regulation is a new way to boost the OER electrocatalytic activity.