Oxygen Evolution Reaction Applications Research Articles

(Digital Presentation) Improving Oxygen Evolution Reaction Performance and Durability Using Rhombic Dodecahedral Pt3(Ni,X) Nanoparticles with Metal Oxide Supports

The supply infrastructure and production of hydrogen remains a limiting aspect in the introduction of polymer electrolyte fuel cell (PEFC) technologies.[1] The creation of highly efficient electrocatalysts is limited by predominantly carbon-based support systems which corrode readily during the oxygen evolution reaction (OER).[2] In acidic environments, iridium and ruthenium electrocatalysts with unary, binary, and ternary compositions have been used to achieve excellent OER results, however, carbon corrosion remains an issue for performance over long periods of time. The objective of this work is to examine the effect of highly active ternary based Pt3(Ni,X) rhombic dodecahedral nanoframes loaded onto metal oxide supports.Novel platinum-based electrocatalysts have been developed to improve catalytic activity and overall durability in acidic environments. Of note is the creation of binary Pt3Ni in a rhombic dodecahedral shape with a Pt skin synthesized.[3] These nanoparticles demonstrate very high specific/mass activities and are comparably durable over 10,000 potential cycles.Previous work[4] has been able to recreate the Pt3Ni rhombic dodecahedron under different synthesis conditions allowing for more rapid manufacture. These nanoparticles were used in combination with nitrogen-doped carbon support to examine the effects of surface nitrogen as anchoring sites. Examination using XPS, electrochemical stripping, and SEIRAS shows that the nitrogen sites alter the d-band center of surface Pt in addition to creating a more homogenous distribution of the nanoparticles. The addition of a ternary element allows for additional fine tuning of the d-band center of platinum near the particle surface.The oxygen evolution reaction requires a higher potential range which leaves carbon-based support systems susceptible to corrosion.[2] Several metal oxide support systems have been investigated as potential candidates, with a particular focus on material conductivity. Antimony tin oxide (ATO) shows promise as a relatively conductive metal oxide support for OER applications.[2] Furthermore, ATO shows lower dissolution rates when compared to other tin oxides in similar acidic environments.[5] As mentioned, iridium and ruthenium are used predominantly for OER in acidic environments. Therefore, the ternary metal additions (X) used in this work include PtNiIr and PtNiRu based nanoframes. These nanoframes have been successfully loaded onto ATO metal oxide supports. These catalyst support systems show promising OER results, even when compared to carbon supported NFs, as well as excellent durability. Examination was done using Scanning Tunneling Electron Microscopy (STEM), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), X-ray absorption spectroscopy (XAS), and rotating disk electrode (RDE) electrochemical measurement. This work could lead to significant improvements into electrocatalyst activity and durability which are necessary to implement PEFC technology onto a global scale.

Room-temperature solution-processed sharp-edged nanoshapes of molybdenum oxide for supercapacitor and electrocatalysis applications

We introduce a simple room-temperature (25–27 °C) solution process-inspired approach for obtaining sharp-edged nanoshapes like nanocubes, nanorods and nanoparticles of molybdenum oxide (MoO3) on a stainless-steel conducting substrate for supercapacitor and electrocatalysis applications. The nanoshape of MoO3 has strikingly been changed from nanocubes to nanopaticles dependig on HCl concentration. The MoO3 electrodes of different morphologies are systematically characterized by various characterization techniques for confirming phase, structure, and surface elementals. The electrochemical studies exhibit significant enhancement in specific capacitance and oxygen evolution reaction (OER) activity for MoO3 nanorod-based electrode. The specific capacitance of 2561.53 F g−1 for MoO3 nanorods is much higher than 608.20 F g−1 and 400.28 F g−1 for nanocubes and nanoparticles, respectively. Besides, with the 98.59% capacitance retention up to 2000 cycles, the electrode consisting nanorods is found to be highly stable. In the commercial point of view, the as-fabricated MoO3//MoO3 symmetric device adduces excellent energy/power density (69.06 Wh kg−1/1336.63 W Kg−1) at current density of 1 A g−1. The laboratory panel, Center for Nanomaterials & Energy Devices, containing nearly 42 LEDs has been ignited with full intensity using MoO3//MoO3 symmetric device as the practical demonstration of electrode material. From supercapacitor study, the MoO3 nanorod-based electrode endows excellent OER activity (overpotential of 246 mV; Tafel slope of 36 mV dec-1). In both cases, the MoO3 nanorod-based electrode produces excellent chemical and cyclic stability. Overall electrochemical results demonstrate that the MoO3 nanorod-based electrode would be excellent electrode material for supercapacitor as well as OER applications. The proposed room-temperature solution synthesis process is valuable and well effective in view of trouble-free, cost-effective, and scalability for commercial benefits.

Facile eco-friendly synthesis of rare-earth cobaltite-based perovskite nanostructures as electrocatalysts for oxygen evolution reaction

Perovskite (ABO3) Structured gadolinium cobaltite (GdCoO3) nanorods and lanthanum cobaltite (LaCoO3) nanoplates are prepared via an eco-friendly green synthesis approach. The Perovskite-based nanostructures show an excellent oxygen evolution reaction (OER) with an overpotential of about 340 mV (LaCoO3) and 320 mV (GdCoO3) at a current density of 10 mA cm−2 in an alkaline medium. Based on the findings, GdCoO3 could be an excellent candidate as a high-performance electrocatalyst in OER application.

Route to the Structure-Controlled Synthesis of Fe Nanobelts and Their Oxygen Evolution Reaction Application.

Belt-shaped metal-organic frameworks (MOFs) have received extensive attention because of their unique structure. In this Communication, Fe-MOF nanobelts were synthesized by a solvothermal method with Fe2+ as the metal source and could not be obtained by using Fe3+ as the metal source. The final result shows that Fe2+ played a transitional role in the process of achieving belt-shaped and cubelike structural changes. Our work provides an idea for the synthesis of belt-shaped MOFs and promotes the development of electrocatalysts.

Isovalent anion-induced electrochemical activity of doped Co3V2O8 for oxygen evolution reaction application.

The activity of an OER electrocatalyst is a strong function of the reaction kinetics at the active sites, which can be influenced by catalytic engineering (e.g., heterostructure, doping, and the addition of cocatalysts). Herein, we report the improved reaction kinetics of cobalt oxide for the OER via the addition of high valence vanadium and thereafter doping with sulphur (S-Co3V2O8). The addition of vanadium increases the oxygen vacancy while the doping of sulphur increases the electronic conductivity of the electrocatalyst. The synergic effect of the oxygen vacancy and electronic conductivity increases the activity of S-Co3V2O8. Furthermore, S-Co3V2O8 showed the least Tafel slope, which showed the activity enhancement towards the oxygen evolution reaction. Moreover, the underlying reaction mechanism is explored by electrochemical impedance spectroscopy, which reveals that the ratio of polarisation resistance to double-layer capacitance is minimum for S-Co3V2O8, indicating the highest activity.

Controllable Synthesis of Graphene-Encapsulated NiFe Nanofiber for Oxygen Evolution Reaction Application

Carbon-Encapsulated NiFe Nanofiber NixFey@C-CNFs have been demonstrated to be promising candidates to replace conventional nobel metals-based catalysts for oxygen evolution reaction. Here, we developed a facile method of electrospinning and high temperature carbonization to synthesize NixFey@C-CNFs catalysts. It is proved that Ni3Fe7@C-CNFs exhibited low overpotential (245 mV) and excellent stability in alkaline electrolyte for OER. This work provides a good platform for the synthesis and design of graphene-encapsulated alloy catalysts.

Enhancement of the OER Kinetics of the Less-Explored α-MnO2 via Nickel Doping Approaches in Alkaline Medium.

Development of a low-cost transition metal-based catalyst for water splitting is of prime importance for generating green hydrogen on an industrial scale. Recently, various transition metal-based oxides, hydroxides, sulfides, and other chalcogenide-based materials have been synthesized for developing a suitable anode material for the oxygen evolution reaction (OER). Among the various transition metal-based catalysts, their oxides have received much consideration for OER, especially in lower pH condition, and MnO2 is one of the oxides that have widely been used for the same. The large variation in the structural disorder of MnO2 and internal resistance at the electrode-electrolyte interfaces have limited its large-scale application. By considering the above limitations of MnO2, here in this work, we have designed Ni-doped MnO2 via a simple wet-chemical synthetic route, which has been successfully applied for OER application in 0.1 M KOH solution. Doping of various quantities of Ni into the MnO2 lattices improved the OER properties, and for achieving 10 mA/cm2 current density, the Ni-doped MnO2 containing 0.02 M of Ni2+ ions (coined as MnO2-Ni0.002(M)) demands only 445 mV overpotential, whereas the bare MnO2 required 610 mV overpotential. It has been proposed that the incorporation of nickel ions into the MnO2 lattices leads to an electron transfer from the Ni3+ ions to Mn4+, which in turn facilitates the Jahn-Teller distortion in the Mn-O octahedral unit. This electron transfer and the creation of a structural disorder in the Mn sites result in the improvization of the OER properties of the MnO2 materials.

Engineering Lattice Oxygen Activation of Iridium Clusters Stabilized on Amorphous Bimetal Borides Array for Oxygen Evolution Reaction.

Developing robust oxygen evolution reaction (OER) catalysts requires significant advances in material design and in-depth understanding for water electrolysis. Herein, we report iridium clusters stabilized surface reconstructed oxyhydroxides on amorphous metal borides array, achieving an ultralow overpotential of 178 mV at 10 mA cm-2 for OER in alkaline medium. The coupling of iridium clusters induced the formation of high valence cobalt species and Ir-O-Co bridge between iridium and oxyhydroxides at the atomic scale, engineering lattice oxygen activation and non-concerted proton-electron transfer to trigger multiple active sites for intrinsic pH-dependent OER activity. The lattice oxygen oxidation mechanism (LOM) was confirmed by in situ 18 O isotope labeling mass spectrometry and chemical recognition of negative peroxo-like species. Theoretical simulations reveal that the OER performance on this catalyst is intrinsically dominated by LOM pathway, facilitating the reaction kinetics. This work not only paves an avenue for the rational design of electrocatalysts, but also serves the fundamental insights into the lattice oxygen participation for promising OER application.

Engineering Lattice Oxygen Activation of Iridium Clusters Stabilized on Amorphous Bimetal Borides Array for Oxygen Evolution Reaction

AbstractDeveloping robust oxygen evolution reaction (OER) catalysts requires significant advances in material design and in‐depth understanding for water electrolysis. Herein, we report iridium clusters stabilized surface reconstructed oxyhydroxides on amorphous metal borides array, achieving an ultralow overpotential of 178 mV at 10 mA cm−2 for OER in alkaline medium. The coupling of iridium clusters induced the formation of high valence cobalt species and Ir–O–Co bridge between iridium and oxyhydroxides at the atomic scale, engineering lattice oxygen activation and non‐concerted proton‐electron transfer to trigger multiple active sites for intrinsic pH‐dependent OER activity. The lattice oxygen oxidation mechanism (LOM) was confirmed by in situ 18O isotope labeling mass spectrometry and chemical recognition of negative peroxo‐like species. Theoretical simulations reveal that the OER performance on this catalyst is intrinsically dominated by LOM pathway, facilitating the reaction kinetics. This work not only paves an avenue for the rational design of electrocatalysts, but also serves the fundamental insights into the lattice oxygen participation for promising OER application.

Vanadium-induced fragmentation of crystalline CoFe hydr(oxy)oxide electrocatalysts for enhanced oxygen evolution reaction

Transition metal hydr(oxy)oxides are one of the most efficient electrocatalysts towards oxygen evolution reaction (OER). However, structural-dependant and low stability severely hinder their overall performance and catalytic efficiency. Herein, we report the enhancement of OER activity via vanadium doping into the CoFe hydr(oxy)oxide electrocatalyst (denoted as CoFeV). Our results show that the incorporation of vanadium induces fragmentation of the polycrystalline structure of the CoFe hydr(oxy)oxide (CoFe) and transformation to a more active amorphous structure, greatly exposing the CoO and FeOOH active sites on the surface for OER. The optimised electrocatalyst exhibits an overpotential of 376 mV to reach a current density of 10 mA cm−2 and requires a small Tafel slope of 26 mV dec−1 for OER in alkaline media. These results illustrate that vanadium doping can efficiently improve the catalytic activity of CoFeV which can be extended to other vanadium-doped transition metal hydr(oxy)oxides as promising electrocatalysts for OER applications.

PH-universal OER electrocatalyst

Catalyst Design The oxygen evolution reaction (OER) is the key electrocatalytic process in many electrochemical systems, including water splitting and metal–air batteries. Because of the acid-aggressive and strongly corrosive media, the development of electrocatalysts for OER applications that could efficiently operate over the long term is an outstanding problem. Zhang et al. developed a sodium-doped amorphous, crystalline RuO2 with rich oxygen vacancies that displays high catalytic stability and competitive OER activity over a wide pH range, including strongly acidic conditions. Density functional theory calculations revealed that the underlying mechanism is possible in other similar systems, implying that this work offers a new pathway with which to develop efficient OER electrocatalysts under pH-universal conditions. Angew. Chem. Int. Ed. Engl. 60 , 18821 (2021).

Synergistic Coupling of NiTe Nanoarrays with FeOOH Nanosheets for Highly Efficient Oxygen Evolution Reaction

AbstractHydrogen is the most promising alternative energy source in the face of energy crisis, and water splitting is a green strategy for hydrogen generation. The oxygen evolution reaction (OER) is the essential half‐reaction in electrochemical water splitting, and thus development and exploration of electrocatalysts with excellent performance are vital to prompt the application of OER. Due to the unique electronic properties of NiTe and strong synergistic interaction between NiTe and FeOOH, NiTe@FeOOH hybrid nanorods were successfully fabricated on Ni foams (NF) by a hydrothermal reaction step and another in‐situ growth step for the first time without consuming any extra energy. The 3D structure of the NiTe@FeOOH/NF was confirmed by powder X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS) and energy dispersive spectrometry (EDS) mapping technologies. Electrochemical measurements showed that the as‐prepared NiTe@FeOOH/NF needs only an overpotential of 241 mV to achieve a current density of 10 mA cm−2 in 1.0 M KOH and requires 1.341 V to drive 10 mA cm−2 in 1 M KOH with a 0.33 M urea, showing excellent long‐term stability. The NiTe@FeOOH/NF as the bifunctional electrocatalyst in an electrolyzer shows high efficiency with a cell voltage of 1.50 V at 10 mA cm−2. This work can provide a new efficient method to construct highly active and cost‐effective OER catalysts.

Platinum Nanoparticles Decorated IrO2@MWCNT as an Improved Catalyst for Oxygen Evolution Reaction

AbstractIn this paper, IrO2 nanoparticles supported on multi‐walled carbon nanotubes (MWCNTs) are synthesized via a facile hydrothermal method and calcination process at different temperature. Platinum nanoparticles decorated IrO2@MWCNT‐400 °C are prepared by chemical reduction method. The influence of MWCNTs and Pt on physicochemical properties and oxygen evolution reaction (OER) activity of IrO2@MWCNT composites were studied via transmission electron microscope (TEM), X‐ray diffraction (XRD), Raman spectra, thermogravimetric analysis (TGA), X‐ray photoelectron spectroscopic (XPS) and electrochemical methods. Among the samples, Pt/IrO2@MWCNT‐400 °C exhibits better catalytic activity with an overpotential of 270 mV at the current density of 10 mA cm−2 with a low Tafel slope of 85.1 mV dec−1. The outstanding OER performance of Pt/IrO2@MWCNT‐400 °C is ascribed to the introduction of the MWCNTs, which can not only act as a support to prevent agglomeration of IrO2 nanoparticles that produces high surface area of catalytic sites, but also facilitates electron transfer between IrO2 nanoparticles and MWCNTs. On the other hand, the Pt optimizes electronic structure for excellent electrocatalytic performance. Therefore, the Pt/IrO2@MWCNT‐400 °C catalyst is a good choice for application in OER.

Highly Enhanced OER Performance by Er-Doped Fe-MOF Nanoarray at Large Current Densities.

Great expectations have been held for the electrochemical splitting of water for producing hydrogen as a significant carbon-neutral technology aimed at solving the global energy crisis and greenhouse gas issues. However, the oxygen evolution reaction (OER) process must be energetically catalyzed over a long period at high output, leading to challenges for efficient and stable processing of electrodes for practical purposes. Here, we first prepared Fe-MOF nanosheet arrays on nickel foam via rare-earth erbium doping (Er0.4 Fe-MOF/NF) and applied them as OER electrocatalysts. The Er0.4 Fe-MOF/NF exhibited wonderful OER performance and could yield a 100 mA cm−2 current density at an overpotential of 248 mV with outstanding long-term electrochemical durability for at least 100 h. At large current densities of 500 and 1000 mA cm−2, overpotentials of only 297 mV and 326 mV were achieved, respectively, revealing its potential in industrial applications. The enhancement was attributed to the synergistic effects of the Fe and Er sites, with Er playing a supporting role in the engineering of the electronic states of the Fe sites to endow them with enhanced OER activity. Such a strategy of engineering the OER activity of Fe-MOF via rare-earth ion doping paves a new avenue to design other MOF catalysts for industrial OER applications.

Comparative study on supercapacitive and oxygen evolution reaction applications of hollow nanostructured cobalt sulfides

Due to the diversity of sulfur valence in cobalt-based sulfides, it is difficult to control the crystal phase and composition of the products during synthesis. Herein, a one-pot hydrothermal method is reported to self-assemble the cobalt sulfides (CoS2, Co9S8 and Co3S4) with hollow nanostructures. The whole preparation process is simple and mild, avoiding high temperature calcination. The performances of the three kinds of cobalt sulfide in superior supercapacitors and electrocatalytic oxygen evolution performance applications follow the order of CoS2 > Co9S8 > Co3S4. Further analysis demonstrates that the performance difference in these cobalt sulfides may be attributed to three factors: the presence of the coordination environment of Co and the presence of continuous network of Co–Co bonds. The distinctive electrochemical performance of CoS2 and Co9S8 may help us to better understand the excellent electrochemical activity of metal polysulfides and metal sulfides after doping or alloying. Therefore, this work may provide a reference in understanding and designing the electrode materials for highly efficient applications in the fields of energy storage and conversion.

Controllable Synthesis of 2D Nonlayered Cr2S3 Nanosheets and Their Electrocatalytic Activity Toward Oxygen Evolution Reaction

The design of oxygen evolution reaction (OER) electrocatalysts based on Earth-abundant materials holds great promise for realizing practically viable water-splitting systems. In this regard, two-dimensional (2D) nonlayered materials have received considerable attention in recent years owing to their intrinsic dangling bonds which give rise to the exposure of unsaturated active sites. In this work, we solved the synthesis challenge in the development of a 2D nonlayered Cr2S3 catalyst for OER application via introducing a controllable chemical vapor deposition scheme. The as-obtained catalyst exhibits a very good OER activity requiring overpotentials of only 230 mV and 300 mV to deliver current densities of 10 mA cm−2 and 30 mA cm−2, respectively, with robust stability. This study provides a general approach to optimize the controllable growth of 2D nonlayered material and opens up a fertile ground for studying the various strategies to enhance the water splitting reactions.

In-situ self-reconstruction of Ni–Fe–Al hybrid phosphides nanosheet arrays enables efficient oxygen evolution in alkaline

Developing efficient oxygen evolution reaction (OER) electrocatalysts with earth-abundant elements is very important for sustainable H2 generation via electrochemical water splitting. Here we design a crystalline-amorphous Ni–Fe–Al hybrid phosphides nanosheet arrays grown on NiFe foam for efficient OER application. Dynamic surface reorganization of phosphides at anodic/cathodic polarizations is probed by in situ Raman spectroscopy. The reconstructed amorphous Ni(Fe)OOH species are determined as the active phases that facilitate the OER process. This unique electrode shows highly catalytic activity toward water oxidation, achieving the current densities of 10 and 100 mA cm−2 at 181 and 214 mV in 1 M KOH, respectively. Meanwhile, it also exhibits excellent stability at a large current density of 100 mA cm−2 for over 60 h. This work reveals the dynamic structural transformation of pre-catalyst in realistic conditions and highlights the important role of oxyhydroxides as real reactive species in OER process with high activity.

Co-doped Ni3S2 ultrathin nanosheets for efficient oxygen evolution catalysis

Oxygen evolution reaction (OER) sets the huge obstacle for water electrolysis application, and the low-cost catalysts with small overpotential and fast kinetics are highly needed. Herein, cobalt-doped Ni3S2 nanosheets constructed flower-like architecture is grown on nickel foam (Co-Ni3S2/NF) toward OER application. It is found that, heteroatom doping induces positive effects for OER, including the modulated electronic structure, more active sites, and accelerated charge transfer. Nanosheets structure assures exposed active sites and shortened charge transfer path. Benefited from the aforementioned advantages, the as-prepared sample exhibits impressive catalysis performances, such as ultralow overpotential of 160 mV at current density of 10 mA cm−2, small Tafel slope of 49 mV dec−1, and high stability, which behaves as the promising catalyst for OER.

The construction of stable Ru/RuO2 porous reticular heterostructure with highly efficient electrocatalytic activity for oxygen evolution reaction

A facile construction of Ru/RuO2 composite with porous reticular structure (denoted as Ru/RuO2-PRS) by controllable pyrolysis of Ru3+ coordinated cyanoguanidine was presented for oxygen evolution reaction (OER). The Ru/RuO2 heterostructure was identified in Ru/RuO2-PRS. Taking the advantages of the Ru/RuO2 heterostructure and large specific surface area, Ru/RuO2-PRS exhibits much more improved OER activity with much lower onset potential and overpotential to reach the current density of 10 mA cm−2 compared with RuO2 porous powder and RuO2 nano-particles counterparts in both acidic and alkaline solution. Specifically, Ru/RuO2-PRS exhibits much improved durability because the unique Ru/RuO2 heterostructure relieves the dissolution of RuO2 at high anodic potential that has been the bottleneck of Ru-based catalysts for OER, especially in acidic electrolyte. This study provides a new strategy to promote the OER application in acidic solution.

Mn-doped NiCo2S4 nanosheet array as an efficient and durable electrocatalyst for oxygen evolution reaction

The development of self-supported nanosheet materials with porous multiple active sites has enormous potential for the application of oxygen evolution reaction (OER). Herein, we reported a three-dimensional (3D) porous nanosphere Mn-NiCo2S4/NF catalyst for OER. As a result, the simple Mn doping strategy results in good electrocatalytic performance and outstanding stability. During the OER, the Mn-NiCo2S4/NF only needs a small overpotential of 220 mV (40 mV lower than pure NiCo2S4/NF) to achieve the current density of 10 mA cm−2, which is mainly due to a large number of exposed active sites and adequate pathways for mass diffusion and oxygen gas release. Moreover, Mn doping optimizes the electronic structure and thus facilitates electron transport, leading to superior electrocatalytic performance. The catalyst exhibits incredible corrosion resistance in 1 M KOH solution for 60 h or more. This work provides a valuable method to synthesize a low cost, high-efficiency, and corrosion resistant transition metal electrocatalyst for oxygen evolution using heteroatom doping strategy.