Materials For Oxygen Evolution Reaction Research Articles

Synergistic modulation of active site of NiO via cobalt doping by solution combustion for improving oxygen evolution reaction

The development of robust, highly efficient, inexpensive electrocatalyst for the oxygen evolution reaction (OER) is very necessary to minimize the overpotential of water splitting and boosts up the practicality of related energy systems. Here in nanoparticles of cobalt doped NiO of the composition Ni1-xCoxO (X = 0, 0.1, 0.2, 0.3, 0.4, 0.5) have been successively synthesized via single step solution combustion method (SCM). The time and energy saving SCM is a self-sustained combustion reaction which helps to control the morphology and size of the nanomaterials. Doping of oxides and construction of hetero junctions are some of the distinctive advantages of SCM. During the combustion process large amount of gas evolution will take place and produce nanomaterial with large specific surface area and porosity, which provide some exceptional behavior to the resulting nanomaterials. The results of structural characterization show that SCM is a functional strategy for the synthesis of pure single-phase Co doped NiO nanoparticles. Among the series of Co doped NiO, Ni0.6Co0.4O showed drastically enhanced OER activity with much lower overpotential of 370 mV and a lower Tafel slope of 69 mV/dec and display good stability in alkaline media. The OER performance of Co doped NiO is higher because of the improved electronic conductivity caused by the partial substitution of Ni2+ by Co2+ in the NiO matrix. In addition, as the Co concentration increases the porous nature of NiO also increases up to x = 0.4 after that aggregation of nanoparticles takes place.The porous nature of material helps to expand the contact area of electrode and electrolyte and favors more active sites for OER. The strategy used for doping Co into NiO proposes a new way to develop electrochemically active material for OER.

Effect of Fe on Calcined Ni(OH)2 Anode in Alkaline Water Electrolysis

Ni (hydr)oxide is a promising and inexpensive material for oxygen evolution reaction (OER) catalysts and is known to dramatically increase the activity when used with Fe. Herein, we basified a Ni(II) solution and coated layered Ni(OH)2 on Ni coins to prepare a template with high stability and activity. To evaluate the stability and catalytic activity during high-current-density operation, we analyzed the electrochemical and physicochemical properties before and after constant current (CC) operation. The electrode with a Ni(OH)2 surface exhibited higher initial activity than that with a NiO surface; however, after the OER operation at a high-current density, degradation occurred owing to structural destruction. The activity of the electrodes with a NiO surface improved after the CC operation because of the changes on the electrode-surface caused by the CC operation and the subsequent Fe incorporation from the Fe impurity in the electrolyte. After confirming the improvement in activity due to Fe, we prepared NiFe-oxide electrodes with improved catalytic activity and optimized the Ni precursor and Fe loading solution concentrations. The Ni-Fe oxide electrode prepared under the optimal concentrations exhibited an overpotential of 287 mV at a current density of 10 mA/cm2, and a tafel slope of 37 mV dec−1, indicating an improvement in the OER activity.

Advanced Design of Metal Nanoclusters and Single Atoms Embedded in C1N1‐Derived Carbon Materials for ORR, HER, and OER

AbstractSingle atoms and nanoclusters of Fe, Ni, Co, Cu, and Mn are systematically designed and embedded in a well‐defined C1N1‐type material that has internal cavities of ≈0.6 nm based on four N atoms. These N atoms serve as perfect anchoring points for the nucleation of small nanoclusters of different metal natures through the creation of metal‐nitrogen (TM‐N4) bonds. After pyrolysis at 800 °C, TM@CNx‐type structures are obtained, where TM is the transition metal and x < 1. Fe@CNx and Co@CNx are the most promising for oxygen reduction reaction and hydrogen evolution reaction, respectively, with a Pt‐like performance, and Ni@CNx is the most active for oxygen evolution reaction (OER) with an EOER of 1.59 V versus RHE, far outperforming the commercial IrO2 (EOER = 1.72 V). This systematic and benchmarking study can serve as a basis for the future design of advanced multi‐functional electrocatalysts by modulating and combining the metallic nature of nanoclusters and single atoms.

Role of oxygen vacancies on surface reaction of water oxidation in WO3 studied by density functional theory (DFT) and experiment

Oxygen vacancies (Vo) play an important role on light absorption and charge separation in the semiconductor-based oxygen evolution reaction (OER). However, its role on the surface reaction in OER are not clear. Here, in this study, we investigated the role of Vo focusing on the surface reaction in OER on WO3 by using density functional theory (DFT) calculations and experiment approaches. The DFT calculations show that on (001) surface of WO3, the Vo can only be stable under ∼0.8 nm of the top surface during OER condition. Otherwise, it will be filled by the oxygen atoms from water molecules adsorbing on the top surface of the catalyst during OER. The Bader charge analysis shows there are excess electrons left by Vo can transfer to the OER intermediates and change its binding energy. Due to this, the stable Vo could reduce the overpotential of OER. To confirm this, a series of WO3 with exposed (001) surfaces containing different Vo concentrations have been synthesized by NaBH4 reduction method. The existence of Vo has been charactered by light absorption, XPS and EPR. The sample with the same Vo concentration of theoretical calculations shown best OER performance and the oxygen evolution reaches 318 μmolg−1h−1. This work gives new insights into further design OER materials based on the role of Vo on the surface reaction.

Two-Dimensional Materials for High-Performance Oxygen Evolution Reaction: Fundamentals, Recent Progress, and Improving Strategies

Open AccessRenewablesREVIEWS24 Jan 2023Two-dimensional materials for high-performance oxygen evolution reaction: fundamentals, recent progresses and improving strategies Xiong Yin, Yani Hua and Zhan Gao Xiong Yin Google Scholar More articles by this author , Yani Hua Google Scholar More articles by this author and Zhan Gao Google Scholar More articles by this author https://doi.org/10.31635/renewables.023.202200003 SectionsAboutPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Oxygen evolution reaction (OER) has an essential role in many energy storage and conversion technologies, but its high overpotential and sluggish kinetics seriously astrict the energy efficiency. The development of efficient and inexpensive OER electrocatalysts is still a grand challenge. Two-dimensional (2D) materials with unique structure and electronic properties have wide application prospects toward OER. In this review, firstly introducing OER electrocatalytic mechanisms and some crucial parameters for evaluating OER electrocatalysts, the latest progresses in the design and construction of 2D materials for OER is systematically reviewed, including layered double hydroxides, 2D carbon materials, transition metal dichalcogenides, metal oxide and phosphide nanosheets, metal-organic frameworks, covalent-organic frameworks and MXenes. Emphatically, some effective design and optimization strategies to improve electrocatalytic activity and durability of 2D materials as OER electrocatalysts are comprehensively generalized. The advantages and shortcomings of these 2D materials are analyzed in detail and their practical applications are deeply understood, which is crucial for the rational design of high-performance OER electrocatalysts. Finally, the challenges and future development opportunities of 2D materials for enhanced OER are discussed. Our review is expected to provide certain guidance for the development of new low-cost 2D materials as advanced OER electrocatalysts. Download figure Download PowerPoint Previous articleNext article FiguresReferencesRelatedDetails Issue AssignmentNot Yet Assigned Copyright & Permissions© 2023 Chinese Chemical Society Downloaded 0 times PDF downloadLoading ...

Synthesis of Hollow Leaf-Shaped Iron-Doped Nickel–Cobalt Layered Double Hydroxides Using Two-Dimensional (2D) Zeolitic Imidazolate Framework Catalyzing Oxygen Evolution Reaction

Layered double hydroxides (LDHs) have been reported as one of the most effective materials for oxygen evolution reaction (OER) catalysts, which are prone to hydrolysis and oxidation under OER conditions. Metal–organic frameworks (MOFs) are porous materials with high crystallinity and internal surface area. The design of LDHs based on MOFs has attracted increasing attention owing to their high surface area, exposed catalysis sites, and fast charge/mass transport kinetics. Herein, we report a novel approach to fabricate a leaf-shaped iron-doped nickel–cobalt LDH (L-Fe-NiCoLDH) derived from a two-dimensional (2D) zeolitic imidazolate framework with a leaf-like morphology (ZIFL). Iron doping played a significant role in enhancing the specific surface area, affecting the OER performance. L-Fe-NiCoLDH showed high OER performance with an overpotential of 243 mV at 10 mA cm−2 and high durability after 20 h. The design of LDHs based on the leaf morphology of MOFs offers tremendous potential for improving OER efficiency.

Effect for the electronic configurations of LuVO4 induced by D4h crystal-field-splitting discovered in the systematic DFT investigation on photocatalysis capacities of vanadates

Vanadates are always a family of promising photocatalytic materials for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). To date, there is lack of systematic research and comprehensive comparison for different vanadates, especially rare-earth vanadates with outstanding optical properties, resulting in ambiguous priority for performance development of different materials. Therefore, crystal structures, optical properties, electronic structures and photocatalysis capacities of twenty-one different vanadates were investigated in details and systematically. AgVO3-C2/m is found to be the most favored in visible-light absorption, while SrVO3-Pm3¯m, LaVO3-Pnma, LaVO3-P21/n, CrVO4-Cmcm and FeVO4-P1¯ are predicted to be competitive in photo-electric conversion. Besides the essential capabilities for driving OER and HER are revealed in the examination of electronic structures, a novel phenomenon is discovered that valence band is mostly contributed by O 2p and Lu 4f states in the band structure of LuVO4-I41/amd, which has been discussed in the framework of crystal field theory, considering Jahn-Teller effects. And it can be described as tetragonal (D4h) symmetry-induced splitting Lu 4f orbitals into five orbitals of closely spaced energies. The incomplete occupation of Lu 4 fz3 orbital induces the metallic ground state and provides the opportunity to adopt donor electrons, driving the HER circle. Furthermore, effect on the electron configurations of V3+t2g2e2 for LaVO3 and V4+t2g1 for SrVO3 induced by Oh and D2h crystal-field-splitting, and the d-d electron transition between orbitals are proposed to provide a novel and essential research route about the photocatalysis capacities of other vanadates.

A polymeric hydrogel electrocatalyst for direct water oxidation

Metal-free electrocatalysts represent a main branch of active materials for oxygen evolution reaction (OER), but they excessively rely on functionalized conjugated carbon materials, which substantially restricts the screening of potential efficient carbonaceous electrocatalysts. Herein, we demonstrate that a mesostructured polyacrylate hydrogel can afford an unexpected and exceptional OER activity – on par with that of benchmark IrO2 catalyst in alkaline electrolyte, together with a high durability and good adaptability in various pH environments. Combined theoretical and electrokinetic studies reveal that the positively charged carbon atoms within the carboxylate units are intrinsically active toward OER, and spectroscopic operando characterizations also identify the fingerprint superoxide intermediate generated on the polymeric hydrogel backbone. This work expands the scope of metal-free materials for OER by providing a new class of polymeric hydrogel electrocatalysts with huge extension potentials.

Manganese doping regulated the built-in electric field of FeBTC for enhanced photoelectrocatalytic hydrolysis

MOF-based Mott Schottky heterojunction has been researched as a promising photoelectrocatalytic material for oxygen evolution reaction (OER), but activity is severely limited by built-in electric field (BIEF). In this study, trace Mn doping strategy is used to enhance the BIEF of FeBTC/NIF, and the energy level configuration is also adjusted. Prepared Mn-FeBTC/NIF has excellent photoelectric coupling catalytic capability, requiring 309 mV overpotential to excite 100 mA cm−2 under illumination and maintaining stability for up to 48 h under different light conditions. Catalytic excellence stems from the elevated BIEF, which means Mn accelerated charge transport, modulated the charge density around the active center, effectively improving the catalytic activity. Moreover, the addition of Mn can effectively improve the conduction band (CB) and valence band (VB), reduce the energy band gap, improve the light absorption capacity and enhance the photocatalytic performance. This work provides new ideas for increasing the BIEF of heterojunction materials.

Electrocatalytic performance of cobalt oxide and hybrid composite thin films of cobalt Oxide@Polyaniline for oxygen evolution reaction

Water splitting is the process in which oxygen evolution reaction is prominent. This can be done by the most affordable technique using an electric field (electrochemical method). Keeping this in mind, we have synthesized novel hybrid composite thin films of Co3O4@PANI, to overcome the deficient electrochemical performance of solo Co3O4. The electrocatalytic performance of cobalt oxide and hybrid composite material for oxygen evolution reaction is studied. Cobalt oxide is deposited by the SILAR method, and hybrid composite material is prepared via different methods like electrochemical deposition and SILAR. Morphology, charge transfer resistance, and phase of material are studied with Scanning Electron Microscopy (SEM), Electrochemical Impedance Spectroscopy (EIS) and X-ray diffraction (XRD) respectively. The hybrid composite Co3O4@PANI electrocatalyst manifests high catalytic activity with 258 mV overpotential at 10 mA cm−2 current while solo Co3O4 shows deficient catalytic activity with 323 mV overpotential at 10 mA cm−2 which is examined by Linear swap voltammetry (LSV) and 16.28 mV dec-1 is Tafel slope. This hybrid combination also shows excellent stability for 10 hrs for OER in 1 M NaOH.

Heterointerface engineering of cobalt molybdenum suboxide for overall water splitting.

Highly active and earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are of great significance for sustainable hydrogen generation through alkaline water electrolysis. Here, with an aim to enhance the bifunctional electrocatalytic activity of cobalt molybdate towards overall water splitting, we demonstrate a simple method involving the modulation of the cobalt to molybdenum ratio and creation of phase-modulated heterointerfaces. Samples with varying Co/Mo molar ratios are obtained via a microwave-assisted synthesis method using appropriate starting precursors. The synthesis conditions are modified to create a heterointerface involving multiple phases of cobalt molybdenum suboxides (CoO/CoMoO3/Co2Mo3O8) supported on Ni foam (NF). Detailed electrochemical studies reveal that modulating the composition and hence the interface can tweak the bifunctional electrocatalytic activity of the material for HER and OER and thus improve the overall water splitting efficiency with very high durability over 500 h. To further evaluate the practical applicability of the studied catalyst in water splitting, an alkaline electrolyser is fabricated with the optimized cobalt molybdenum suboxide material (CMO-1.25) as a bifunctional electrocatalyst. A current density of 220 mA cm-2 @1.6 V and 670 mA cm-2 @1.8 V was obtained, and the device showed very good long-term durability.

Hydrothermal growth of 1D VO2 for oxygen evolution reaction

Fascination surface activities offered by nanomaterials have attracted wide attention to be used as electrode materials in oxygen evolution reactions (OER). Among various transition metal oxides (TMOs), the electrochemical behavior of one-dimensional (1D) VO2 is not explored in detail due to a lack of efficient synthesis techniques. Herein, a novel synthesis route is developed to grow fine 1D VO2 following a two-step hydrothermal reaction. XRD, XPS, EDS, SEM, and HRTEM analyses confirm the monoclinic structure of 1D VO2 with fine morphologies having diameters mostly in the range of 10–100 nm. This resulted in the attainment of best-in-class electrode material for Oxygen evolution reaction (OER). VO2 shows an excellent OER activity with a low overpotential of 626 mV at a current density of 10 mA cm−2 with a low Tafel slope of 40.4 mV dec-1. Also, it showed high cyclic stability up to 5000 cycles.

Bimetallic‐Based Electrocatalysts for Oxygen Evolution Reaction

AbstractThe electrochemical oxygen evolution reaction (OER) is a core electrode reaction for the renewable production of high‐purity hydrogen, carbon‐based fuel, synthetic ammonia, etc. However, the sluggish kinetics of the OER result in a high overpotential and limit the widespread application of OER‐based technologies. Recent studies have shown that bimetallic‐based materials with the synergism of different metal components to regulate the adsorption and dissociation energy of intermediates are promising OER electrocatalyst candidates with a lower cost and energy consumption. In the past two decades, tremendous efforts have been devoted to developing OER applications of bimetallic‐based materials with a focus on compositions, phase, structure, etc., to highlight the synergism of different metal components. However, there is a lack of critical thinking and organized analysis of OER applications with bimetallic‐based materials. This review critically discusses the challenges of developing bimetallic‐based OER materials, summarizes the current optimization strategies to enhance both activity and stability, and highlights the state‐of‐the‐art electrocatalysts for OER. The relationship between the componential/structural features of bimetallic‐based materials and their electrocatalytic properties is presented to form comprehensive electronic and geometric modifications based on thorough analysis of the reported works and discuss future efforts to realize sustainable bimetallic‐based OER applications.

Implications of the M-OO∙∙OO-M recombination mechanism on materials screening and the oxygen evolution reaction

Identification of active electrocatalysts for the oxygen evolution reaction (OER), corresponding to the bottleneck in electrolyzers to produce gaseous hydrogen as energy vector, by electronic structure calculations relies on the assumption of the mononuclear mechanism, comprising the *OH, *O, and *OOH intermediates. This mechanistic description is thermodynamically hampered by a scaling relation between the *OH and *OOH adsorbates, which may serve as an explanation why OER catalysts commonly require large overpotentials to reach sufficient current densities. Recently, an alternate OER pathway was proposed that, in contrast to the mononuclear description, consists of the formation of two adjacent *OO adsorbates, and gaseous oxygen is produced by chemical recombination of the neighboring *OO intermediates. In the present manuscript, a data-driven model based on a dedicated assessment of the elementary reaction steps is deduced, which enables evaluating the mononuclear and *OO pathways by the same set of parameters. Potential-dependent volcano plots are constructed to comprehend the energetics of the competing mechanisms. It is demonstrated that the alternate OER pathway consisting of the *OO∙∙*OO recombination step may excel the mononuclear description at overpotentials corresponding to typical OER conditions. Consequently, it is suggested that future studies, aiming at the identification of OER materials, may not omit the *OO∙∙*OO recombination mechanism when using concepts of materials screening in a heuristic fashion or multiscale modeling.

2D/2D core/shell structure of FeCo2O4@NiMn LDH for efficient oxygen evolution reaction

Developing high-performance non-precious metal electrocatalysts for oxygen evolution reaction (OER) is of great significance to the production of green hydrogen fuel. In this work, ultrathin NiMn LDH nanosheets are grown on FeCo2O4 nanoflakes to form a 2D/2D core/shell structure on nickel foam (NF) as an effective catalyst for OER. Owning to the well-designed core/shell heterostructure, large electrochemical active surface area, high electron conductivity, rapid mass/charge transfer, and as well as synergistic effect between FeCo2O4 and NiMn LDH, the core/shell FeCo2O4 @NiMn LDH/NF electrode displays a small Tafel slope of 31.85 mV dec−1 and exhibits a rather low overpotential of 232 mV to deliver the current density of 10 mA cm−2 for OER process, while maintaining good stability for 24 h in alkaline electrolyte. These results demonstrate that FeCo2O4 @NiMn LDH is a promising material for OER.

Construction of Co(CO3)0.5OH/Cu Mott-Schottky heterojunctions on Ni foams as an efficient electrocatalyst for oxygen evolution reaction

Oxygen evolution reaction (OER) is an important semi-reaction in the electrolysis of water, but it requires a cheap and efficient catalyst to solve the inherent problem of slow kinetics. In this work, we present an efficient strategy to improve electrocatalytic performance by constructing a Mott-Schottky heterojunction via the Cu layer. The Co(CO3)0.5OH/Cu/NFs sample with a Mott-Schottky structure was prepared by depositing Co(CO3)0.5OH nanowire arrays on the surface of NFs plated with a Cu layer. The sample can deliver much better OER performance given the low overpotential of 253 mV at 10 mA cm−2, and extremely low Tafel slope of 48 mV dec−1, even lower than that of commercial OER catalyst RuO2. The significant performance enhancement can be attributed to the Mott-Schottky structure of Co(CO3)0.5OH/Cu. In particular, the intrinsic activity of the sample is improved by the Mott-Schottky structure of Co(CO3)0.5OH/Cu, in which the spontaneous electron will transfer from Cu to Co(CO3)0.5OH, hence reducing the OER overpotential. Then, the conductivity of the sample is initially enhanced by the Cu layer, thus improving the charge transport speed in the process of OER. Furthermore, in the constructed sandwich structure, the dense Co(CO3)0.5OH and NF substrates can avoid the corrosion of Cu by the electrolyte, maintaining good stability beyond 50 h. This strategy is also applicable to other OER materials, such as NiFe LDH, CuNi LDH, and CoP, and their performances can be significantly improved. This work provides a universal method of constructing efficient Mott-Schottky electrocatalysts for OER, consequently providing a wide range of application prospects.

One-step construction of FeNi LDH/FeNi2S4 heterojunctions for boosting electrocatalytic oxygen evolution reaction and hybrid capacitive storage

Construction of heterogeneous phases offers a promising strategy to tailor the physiochemical properties of electrode materials to improve their electrochemical performance toward energy conversion and capacitive storage. Herein, the hetero-phase combination of hexagonal FeNi layered double-hydroxide (FeNi-LDH) and spinel phase FeNi2S4 microsphere assembled with nanosheets is synthesized via one-step solvothermal process. Owing to improved components, unique micro-structures and the construction of heterogeneous engineering between FeNi LDH and FeNi2S4 with abundant active interface, FeNi LDH/FeNi2S4 heterojunctions exhibit an excellent electrochemical performance for oxygen evolution reaction (OER) and hybrid capacitive storage. The heterojunctions show low overpotential of 259 mV at 10 mA cm−2, small Tafel slope of 75 mV dec−1, excellent cyclic stability in OER, as well as an improved specific capacity of 472.5C g−1 at 1 A g−1 in hybrid capacitors. The preparation and dual-function applications of FeNi LDH/FeNi2S4 heterojunctions provide a new idea as the advanced electrode materials for electrocatalytic OER and hybrid capacitors.

Electronic Structure Modulation of Sulfur-Retaining Nickel-Based Electrocatalyst to Improve the Oxygen Evolution Reaction

Water electrolysis is considered as a key energy source to produce hydrogen for achieving a clean and sustainable society. Improving the sluggish kinetics of the oxygen evolution reaction (OER) is focused to overcome the limit efficiency of water electrolysis. Transition metals, especially Ni, are one of the most promising materials for the alkaline OER because of good catalytic activities, stabilities and cost efficiency. Ni based materials, such as Ni oxyhydroxides, hydroxides, phosphides and sulfides, are intensively developed for use as OER catalysts. Recently, the sulfurization of transition metals is introduced as an effective method to improve the intrinsic electrocatalytic activities. The role of S has been summarized in 2 ways. S accelerates the regeneration of transition metals in alkaline media that S is dissolved and exchanged with O species. Mullins et al. reported Nickel oxide derived from Ni-S. It exhibits amorphous and large active surface morphology which is favorable OER. The other role is that remaining S modulates the electronic structures of Ni catalysts reducing the energy barrier for the OER. Wu et al. developed ultrathin Fe-doped Ni3S2 for overall water splitting. Based on density functional theory calculations, the Fe-doped Ni3S2 surface exhibits an optimized energy for water adsorption and dissociation, which enhances the intrinsic activity for the OER. However, in-situ/operando experimental studies regarding the effects of residual S are rare.Herein, we report the role of the remaining S in Ni catalysts that exhibit longer Ni-O bonding in the NiOOH phase produced in-situ. C-supported Fe- and Co-doped nickel sulfide catalysts (NiFeCo-S/C) is prepared using a simple impregnation method with heating under an H2S atmosphere. We tested the electrochemical properties of the NiFeCo-S/C in alkaline media of 1 M KOH. It achieved current density of 10 mA cm-2 with only overpotential of 267.2 mV. Also, it maintained the OER activities for 24 h at current densities of 10 and 50 mA cm-2, respectively. Moreover, the prepared catalyst was analyzed the change of electronic structure and bonding group using in-situ/operando X-ray absorption spectroscopy (XAFS) and surface-enhanced Raman spectroscopy (SERS) under OER condition. Based on these results, we could elucidate the effects of the remaining S during the OER. Figure 1

Interface engineering breaks both stability and activity limits of RuO2 for sustainable water oxidation

Designing catalytic materials with enhanced stability and activity is crucial for sustainable electrochemical energy technologies. RuO2 is the most active material for oxygen evolution reaction (OER) in electrolysers aiming at producing ‘green’ hydrogen, however it encounters critical electrochemical oxidation and dissolution issues during reaction. It remains a grand challenge to achieve stable and active RuO2 electrocatalyst as the current strategies usually enhance one of the two properties at the expense of the other. Here, we report breaking the stability and activity limits of RuO2 in neutral and alkaline environments by constructing a RuO2/CoOx interface. We demonstrate that RuO2 can be greatly stabilized on the CoOx substrate to exceed the Pourbaix stability limit of bulk RuO2. This is realized by the preferential oxidation of CoOx during OER and the electron gain of RuO2 through the interface. Besides, a highly active Ru/Co dual-atom site can be generated around the RuO2/CoOx interface to synergistically adsorb the oxygen intermediates, leading to a favourable reaction path. The as-designed RuO2/CoOx catalyst provides an avenue to achieve stable and active materials for sustainable electrochemical energy technologies.

Prussian-blue-analog derived hollow Co3O4/NiO decorated CeO2 nanoparticles for boosting oxygen evolution reaction

Exploration of efficient, inexpensive, and stable electrocatalysts for oxygen evolution reaction (OER) is of great significance for energy conversion and storage. Currently, transition metal oxides (TMOs) show huge potential as electrode materials for OER due to their low-cost, rich redox chemistry and high chemical stability. In this work, we report a facile route for uniformly coating CeO 2 nanoparticles (NPs) on the surface of nickel cobalt Prussian blue analogue (NiCo-PBA) derived Co 3 O 4 /NiO hollow porous nanocubes (Co 3 O 4 /NiO HPN). The accurate control of CeO 2 content on the Co 3 O 4 / NiO HPN (Co 3 O 4 /NiO@CeO 2 HPN) surface can effectively alter the surface electronic states, which tunes the ratio of Co 2+ /Co 3+ and Ni 2+ /Ni 3+ for creating abundant oxygen vacancies. The large surface area of hollow nanocubes derived from NiCo-PBA with porous structure offers more active sites, resulting in the great promotion of OER activity. The prepared Co 3 O 4 /NiO@CeO 2 -2 HPN heterostructure exhibits remarkable OER performance with a low overpotential (290 mV at 10 mA·cm −2 ), small Tafel slope (66 mV dec −1 ) and excellent durability. The present method opens a new avenue to the preparation of low-cost and efficient electrocatalysts in OER. A novel hollow and porous heterostructure of CeO 2 nanoparticles (NPs)-decorated NiO/Co 3 O 4 hollow porous nanocubes (Co 3 O 4 /NiO@CeO 2 HPN) was designed for boosting the oxygen evolution reaction activity. • Co 3 O 4 /NiO@CeO 2 HPN electrocatalyst is designed by an easy to realize strategy. • The microstructure and surface state of the catalyst can be regulated accurately. • Active sites and oxygen vacancies are obtained for boosting the OER performance. • Integration of high catalytic activity and excellent durability together.