Oxygen Evolution Reaction Applications Research Articles

Harvesting high-performance electro-water oxidation and selective MB degradation through dual functional Gd2O3–La2O3 photo-electrocatalysts

Interestingly, catalytic oxygen evolution reaction (OER) in an alkaline medium with minimizing the overpotential is the most trustworthy electrocatalyst for the output of hydrogen energy from copious water electrochemical activity. Currently, amalgamated trivalent cations metal oxides have gained desirability as a low-cost anode electrocatalyst to replace noble metal-supported electrocatalysts for water oxidation and are also used for photo-degradation applications. In the present work, we have successfully synthesized Gd2O3 supported La2O3 composites via hydrothermal pathways for efficient OER and selective methylene blue (MB) degradation applications. XRD, UV–Vis DRS, FT-IR, XPS, SEM-EDX, HR-TEM, DLS, and BET analyzers confirmed the successful synthesis of photo-electrocatalysts. Gd2O3–La2O3 composites achieved 5.66 and 3.37-fold larger surface areas than La2O3 and Gd2O3, respectively. The results of the Gd2O3 supported La2O3 composite electrode demonstrated better OER performance under 1 M KOH, and it exhibited a lower Tafel slope and overpotential of 72 mV dec−1 and 310 mV at 10 mA cm−2. A chronoamperometry examination confirms that the fabricated Gd2O3–La2O3 electrode has good stability at a fixed potential of 1.540 V vs. RHE for water oxidation. Although the, Gd+3 inspired La2O3 electrode actively takes part in OER activity owing to its high Cdl value of 40.222 μF cm−2. The selective degradation of MB dye using the Gd2O3–La2O3 composite achieved an acceptable degradation efficiency of 84.80 % compared to other pollutants under UV-light irradiation for 120 min, and the specified pH condition is 9 for the degradation of MB dye, and it follows the first-order kinetics model. Notably, post-OER and photocatalytic results exhibited good stability and reusability characteristics. Therefore, the Gd2O3–La2O3 catalyst can be used for real-time water oxidation and MB dye removal from polluted water.

Enhancement of BaCeO3 OER performance by generating a nanohybrid with gCN for electrochemical water splitting

Significant research is currently performed on electrochemical water splitting to solve ecological problems and energy issues. Sustainable and eco-friendly energy systems prefer to generate cost-effective electrocatalyst material with higher stability and excellent electrocatalytic activity to speed up the oxygen evolution reaction (OER) process. The current study followed a hydrothermal approach to develop a barium cerium oxide nanohybrid with g-CN (BaCeO3/g-CN) as an electro-catalyst for an efficient OER process in 1.0 M KOH. Physical characteristics analyses confirmed the enhanced activity of the synthesized BaCeO3 (BCO) and BCO/g-CN nanohybrid materials. The evaluated increased performance may be ascribed to improved morphological characteristics and substantial surface area (212 m2 g−1). The nanocomposite as mentioned above (BCO/g-CN) exhibits significant potential for effective OER in electrochemical assessments due to its abundant active spots and accelerated charge transfer process. Further, the electro-catalytic activity of the composite is improved, as demonstrated by a reduced overpotential (η = 210 mV) with Tafel value (36 mV dec−1) in comparison to pristine BCO (η = 262 mV and 52 mV dec−1) for OER. The material exhibited a reduced charge transfer impedance (Rct = 0.7 Ω), confirmed by EIS analysis. It also demonstrated a substantial ECSA (electrochemical active surface area) of 237.5 cm2 as compared to the pure BCO (137.5 cm2) material. Moreover, electrocatalyst material durability for 30 h was assessed by a chronoamperometric study. Thus, BCO/g-CN exhibits a notable rise in electrochemical properties, suggesting that it is a viable candidate for prospective OER applications.

Oxygen evolution reaction activity of carbon aerogel supported Pd–Ni–Al catalysts synthesized by microwave irradiation method

The oxygen evolution reaction (OER) is a critical step for oxygen production during the electrochemical splitting of water. Effective OER catalysts support the development of clean energy technologies by increasing the energy efficiency of these processes. In this study, carbon aerogel (CA) was first synthesized as a catalyst support material using sol-gel, supercritical drying, and pyrolysis process. Then, mono-metallic (Pd/CA, Al/CA), bi-metallic (Pd–Al/CA, Pd–Ni/CA), and tri-metallic (Pd–Ni–Al/CA) catalysts were synthesized by microwave irradiation method. Inductively coupled plasma-mass spectrometry (ICP-MS), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy have been made to examine the structural properties of the synthesized catalysts. Electrochemical analysis was carried out through cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS) in alkaline media (1 M KOH: Methanol) to examine the effect of metal loading of CA support material towards OER performance. All the compositions showed excellent activity toward OER, among all Pd–Ni/CA catalysts showed the highest activity. The OER peak current increased remarkably up to 48 mA cm−2 with methanol addition, which signifies the substantial application of carbon aerogel supported-Pd-Ni-Al catalysts in direct methanol fuel cells (DMFCs). Pd–Ni/CA display high OER performance with maximum diffusion coefficient, Do (6.6 × 10−8 cm2 s−1) and heterogeneous rate constant, ko (4.706 × 10−4 cm s−1), and smaller value of Tafel slope (128 mV dec−1). Electrochemical studies predicted that all the prepared carbon aerogel supported-Pd-Ni-Al catalysts can be used as efficient catalysts for OER and other related electrocatalysis applications.

Biogenic Bovine Serum Albumin/Zn3(PO4)2/Cr2O3 hybrid electrocatalyst for improved oxygen evolution reaction

The fabrication of nanostructured protein-inorganic hybrid materials is crucial for the development of advanced multifunctional materials. Protein-inorganic mesoporous composites are gaining attention due to their remarkable properties, including large surface areas and active surface functional groups. We have successfully synthesized mesoporous BSA/Zn3(PO4)2/Cr2O3 catalysts to improve the kinetics of the oxygen evolution reaction (OER) in electrocatalytic water splitting for sustainable energy generation. This approach utilizes BSA in the synthesis process and is environmentally friendly. By adjusting the BSA quantity, we could control the yield of BSA/Zn3(PO4)2/Cr2O3 mesoporous. We employed various techniques, including FE-SEM, XRD, and FTIR, to analyze the morphology and structural characteristics of the biogenic BSA/Zn3(PO4)2/Cr2O3 electrocatalyst. Our comprehensive evaluation of the electrocatalytic OER activity of the BSA/Zn3(PO4)2/Cr2O3 hybrid structure demonstrated its remarkable performance. The biologically synthesized catalyst exhibited exceptional OER efficiency, maintaining a high current density of 10 mA cm−2 at very low overpotentials (only 216 mV) under alkaline conditions. The elongated peptide backbone of BSA significantly facilitated ion and electron transport, contributing to improved OER activity. The synergistic interaction between various amino acids from BSA and the metal ions within Zn3(PO4)2/Cr2O3 can be attributed to this enhancement, highlighting the potential of this hybrid structure in electrocatalytic OER applications.

Effective OER activity of rhombohedral nickel sulphide nanoparticles supported via reduced graphene oxide

Excessive utilization of fossil fuels is causing significant environmental contamination and energy loss, which has become a major problem today. Thus, there is a growing demand for green energy storage sources, such as water splitting, to address these energy concerns. Hydrogen gas is an economical and environmentally friendly energy source. It is produced from water and is known for being carbon-free. However, in current years, metal sulfides have gained significant interest as an efficient alternative to noble-metal-catalysts due to their capability to contribute to the oxygen evolution reaction (OER). The current work uses a hydrothermal approach to produce NiS/rGO nanocomposite, which is advantageous for commercial applications. It showed higher catalytic efficiency, low cost and convenient accessibility, which improves OER. The efficient fabrication and use of NiS/rGO nanocomposite material were confirmed and evaluated via several analysis approaches, such as XRD, SEM and BET, which showed unique structure, morphology and increased surface area. Furthermore, higher active regions provide a synergistic effect and the composite showed a significantly decreased over-potential (162 mV) at (10 mA/cm2) current-density (j) possessing a Tafel plot (32 mV/dec) for OER in 1 M KOH. The composite showed more active regions and more significant surface area potential for charge transfers due to its distinct structure, which makes the material more stable (40 h). By integrating carbon-based reduced graphene oxide (rGO) into oxygen-deficient NiS, the poor conductivity of the material may be enhanced. This improvement is shown by the low Rct (0.07 Ω) value measured via electrochemical impedance spectroscopy (EIS). The greater surface area (2852.5 cm2) at different scan rates (10–40 mV/s), is evidenced by ECSA measurement. Therefore, research indicates that combining a specific metal sulphide and reduced graphene oxide (rGO) can potentially improve electrocatalyst functionality and make it a feasible choice for OER applications in future due to its cost-effectiveness.

Mn single atoms coordinated with N and O and embedded in activated carbon for supercapacitor and oxygen evolution reaction applications

With the aim of increasing the potential applications of activated carbon (AC) in supercapacitors and zinc-air batteries, the present work prepared AC composites doped with Mn, N and O using various methods. These materials exhibited superior capacitive and oxygen evolution reaction (OER) electrocatalytic activity. Analytical characterizations and density functional theory calculations demonstrated that the specimen subjected to calcination and heating under N2 and NH3 (AC-Mn-3) had a higher specific surface area, an optimized distribution of pyridinic and pyrrolic N and single Mn atom active sites. These factors improved the supercapacitor performance and OER catalytic activity of this material. The hierarchical pore structure of the AC matrix also facilitated electrolyte transport while simultaneously reducing internal resistance and protecting the electrode structure during cycling. An AC-Mn-3 electrode provided a high specific capacitance of 516.20 F/g at 1 A/g while a symmetric supercapacitor based on this electrode delivered an exceptional energy density of 71.69 Wh/kg at a power density of 500 W/kg. When applied to the OER, the AC-Mn-3 achieved a low overpotential of 270.21 mV at 10 mA/cm2 in 1 M KOH. Theoretical calculations suggested that single Mn atoms coordinated with N and O effectively bound oxygenated intermediates to lower the adsorption energy barrier associated with the OER rate-determining step going from OH* to O*. These results provide new insights concerning the mechanism by which improved supercapacitor performance and OER catalytic activity can be realized and demonstrate an effective strategy for AC modification.

Microwave-Assisted Ultrafast Synthesis of Bimetallic Nickel-Cobalt Metal-Organic Frameworks for Application in the Oxygen Evolution Reaction.

Herein, a series of monometallic Ni-, Co- and Zn-MOFs and bimetallic NiCo-, NiZn- and CoZn-MOFs of formula M2(BDC)2DABCO and (M,M')2(BDC)2DABCO, respectively, (M, M'=metal) with the same pillar and layer linkers 1,4-diazabicyclo[2.2.2]octane (DABCO) and benzene-1,4-dicarboxylate (BDC) were prepared through a fast microwave-assisted thermal conversion synthesis method (MW) within only 12 min. In the bimetallic MOFs the ratio M:M' was 4 : 1. The mono- and bimetallic MOFs were selected to systematically explore the catalytic-activity of their derived metal oxide/hydroxides for the oxygen evolution reaction (OER). Among all tested bimetallic MOF-derived catalysts, the NiCoMOF exhibits superior catalytic activity for the OER with the lowest overpotentials of 301 mV and Tafel slopes of 42 mV dec-1 on a rotating disk glassy carbon electrode (RD-GCE) in 1 mol L-1 KOH electrolyte at a current density of 10 mA cm-2. In addition, NiCoMOF was insitu grown in just 25 min by the MW synthesis on the surface of nickel foam (NF) with, for example, a mass loading of 16.6 mgMOF/gNF, where overpotentials of 313 and 328 mV at current densities of 50 and 300 mA cm-2, respectively, were delivered and superior long-term stability for practical OER application. The low Tafel slope of 27 mV dec-1, as well as a low reaction resistance from electrochemical impedance spectroscopy (EIS) measurement (Rfar=2 Ω), confirm the excellent OER performance of this NiCoMOF/NF composite. During the electrocatalytic processes or even before upon KOH pre-treatment, the MOFs are transformed to the mixed-metal hydroxide phase α-/β-M(OH)2 which presents the active species in the reactions (turnover frequency TOF=0.252 s-1 at an overpotential of 320 mV). Compared to the TOF from β-M(OH)2 (0.002 s-1), our study demonstrates that a bimetallic MOF improves the electrocatalytic performance of the derived catalyst by giving an intimate and uniform mixture of the involved metals at the nanoscale.

High-throughput screening of dual atom catalysts for oxygen reduction and evolution reactions and rechargeable zinc-air battery

We provide the rational design of dual atom catalysts (DACs) supported on nitrogen-doped graphene for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) through high-throughput computational screening of M1M2N6-DAC systems, where M1 and M2 represent Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, or Pt metals. We predict that FeRuN6-DAC at the summit of the volcano plot exhibits a low theoretical ORR overpotential (ηORR) of 0.24 V and a low theoretical OER overpotential (ηOER) of 0.19 V. The low ηORR and ηOER result from the catalytic performance of the Fe site being tuned to electronic properties that facilitate adsorption and desorption of the OH* intermediate. Inspired by these hybrid density functional theory (DFT) computational and machine learning (ML) results, we synthesized FeRuN6-DAC, FeN4-SAC, and RuN4-SAC and characterized them using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), and in-situ electron spin resonance (ESR). Our in-situ ESR spectroscopy signifies that the spin of the Fe active site increases with increasing applied potential due to the increase in the concentration of OH* intermediate on Fe. We verified experimentally the predicted catalytic performances, finding that FeRuN6-DAC leads to an experimental ORR overpotential of 0.29 V with a Tafel slope of 104 mVdec−1 and an OER overpotential of 0.27 V with a Tafel slope of 124 mVdec−1. The rechargeable Zinc-air battery setup was fabricated with FeRuN6-DAC in place of the cathode, showing a maximum power density of 0.45 W/cm2 at the current density of 0.44 A/cm2 and good stability after 120 cycles. According to our findings, we demonstrate that DFT-guided strategies are useful for designing advanced DACs applicable to ORR, OER, and Zinc-air battery applications.

Surface functionalization of nickel foam with two-dimensional conjugated MOFs Fe3(hexaiminotriphenylene)2 for highly efficient oxygen evolution reaction

The design of high-efficient, low-cost, and stable electrocatalysts for oxygen evolution reaction (OER) is highly demanding for energy conversion applications. Metal-organic frameworks (MOFs), with large surface area and flexible molecular species, can supply atom-dispersed metal active coordination sites (M−NX, M−SX, M−OX) for OER and have been regarded as potential catalysts for practical applications. However, it is still challenging to use MOFs as OER catalysts directly due to their low conductivity and poor stability. Herein, we successfully synthesized a 2D c-MOF of Fe3(HITP)2 (HITP = 2,3,6,7,10,11-hexaiminotriphenylene) on the surface of nickel foam (NF) by using a layer-by-layer self-assembly strategy. The Fe3(HITP)2/NF-x electrode (x = 5, 10, 15, 20 is the number of cycles) exhibited impressive OER catalytic activity in alkaline electrolyte (1 M KOH), which is superior or comparable to most of the transition metal-based materials reported. Typically, Fe3(HITP)2/NF-15 were able to fully expose the Fe-N4 catalytic sites with an overpotential of 224 mV at a current density of 10 mA·cm−2 and a Tafel slope of 45.4 mV·dec-1. This was mainly attributed to the higher ECSA value, better kinetic process, and fast charge transfer ability of Fe3(HITP)2/NF. In addition, the current density of Fe3(HITP)2/NF-15 remained at 97.3 % of the initial current density after 24 h i-t stability test, showing excellent catalytic stability. This work provided a novel design strategy for the direct application of MOFs to OER applications.

Construction of mesoporous Ni-Co-Mo oxide/sulfide composite composite nanosheet arrays as bifunctional material for charge storage and oxygen evolution reaction applications

At present, energy conversion and energy storage devices are gradually integrated together, which puts forward higher requirements for the design and construction of electrode materials. Herein, bi-functional Co-Mo oxides and Ni/Co sulfides (NCMOS) composite nanosheet arrays on Ni foam are constructed for supercapacitors and oxygen evolution reaction (OER) of water splitting. The Ni-Co-Mo nanosheet precursor is firstly synthesized by stepwise hydrothermal processes and then converted into Ni-Co sulfide and Co-Mo oxide by in-situ sulfurization. The nanoarray and in-situ sulfurization of active materials bring more reactive active sites, optimize reaction kinetics, and shorten the transport path of electrons and charges, which enhance energy storage performance and OER catalytic activity of NCMOS material. In terms of supercapacitor applications, NCMOS exhibits high specific capacity (1332.1 C g–1) and good cycle stability. For OER application, NiCMOS shows lower OER overpotential (290 mV at 100 mA cm–2), smaller Tafel slope (87.2 mV dec–1) and excellent catalytic stability in oxygen evolution for 60 h. The excellent charge storage and OER properties suggest that bi-functional oxide/sulfide composites have great potential in energy conversion and storage-integrated devices.

Silica-Derived Nanostructured Electrode Materials for ORR, OER, HER, CO2RR Electrocatalysis, and Energy Storage Applications: A Review.

Silica-derived nanostructured catalysts (SDNCs) are a class of materials synthesized using nanocasting and templating techniques, which involve the sacrificial removal of a silica template to generate highly porous nanostructured materials. The surface of these nanostructures is functionalized with a variety of electrocatalytically active metal and non-metal atoms. SDNCs have attracted considerable attention due to their unique physicochemical properties, tunable electronic configuration, and microstructure. These properties make them highly efficient catalysts and promising electrode materials for next generation electrocatalysis, energy conversion, and energy storage technologies. The continued development of SDNCs is likely to lead to new and improved electrocatalysts and electrode materials. This review article provides a comprehensive overview of the recent advances in the development of SDNCs for electrocatalysis and energy storage applications. It analyzes 337,061 research articles published in the Web of Science (WoS) database up to December 2022 using the keywords "silica", "electrocatalysts", "ORR", "OER", "HER", "HOR", "CO2RR", "batteries", and "supercapacitors". The review discusses the application of SDNCs for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), carbon dioxide reduction reaction (CO2RR), supercapacitors, lithium-ion batteries, and thermal energy storage applications. It concludes by discussing the advantages and limitations of SDNCs for energy applications.

Synthesis and Oxygen Evolution Reaction Application of a Co-Cd Based Bimetallic Metal-Organic Framework.

In the realm of renewable energy technologies, the development of efficient and durable electrocatalysts is paramount, especially for applications like electrochemical water splitting. This research focuses on synthesizing a novel bimetallic metal-organic framework (BMMOF11) using earth-abundant elements, cobalt (Co) and cadmium (Cd). BMMOF11 showcases a distinctive structure with distorted octahedral chains of CoO and CdO, linked by benzene tricarboxylic acid (BTC). Our study primarily investigates the electrocatalytic efficiency of BMMOF11, particularly in water oxidation reactions. For practical analysis, BMMOF11 was anchored onto nickel foam, forming BMMOF11/NF, to evaluate its electrocatalytic properties. Electrochemical testing revealed that BMMOF11/NF begins water oxidation at an onset potential of 1.62 V versus RHE, demonstrating high activity with a lower overpotential of 0.4 V to achieve a current density of 10 mA/cm2 . Moreover, BMMOF11/NF maintained stable water splitting performance, sustaining a current density of approximately 70 mA/cm2 under a voltage of 1.9 V relative to RHE. These findings indicate that BMMOF11/NF is a promising candidate for large-scale electrochemical water splitting, offering a blend of high activity and stability.

Few-layer MoAlB nanosheets with Al vacancies enhanced hydroxyl adsorption for improved water oxidation kinetics

Few-layer metal borides (MBenes) have attracted much attention in electrocatalytic energy conversion due to the unique physical features, but the present studies are confined to the related bulk materials and the structure-activity relationship is unclear. Here, we successfully synthetized a few-layer exfoliated MoAlB (denoted as EMAB) material as an oxygen evolution reaction (OER) catalyst through a modified etching and exfoliation method to remove the Al atoms and separate the layers. The enhanced hydroxyl adsorption and reduced surface valence of Mo are responsible for the improved OER activity and stability. Density functional theory simulations indicate the hydroxyl adsorption sites are adjusted when removing the Al atoms. The reactive interface for the MAB is the Al layer, while introducing Al vacancies, the hydroxyls prefer to be firstly adsorbed on the Mo sites, and further adsorbed on Al sites, so the energy barrier is largely reduced to accelerate the reaction. This work expands the OER application and mechanism study of MBenes.

Surface addition of Ag on PbO2 to enable efficient oxygen evolution reaction in pH-neutral media

Electrocatalysts, particularly earth-abundant metal oxide ones, exhibit poor performance in catalyzing the oxygen evolution reaction (OER) under neutral conditions due to low ionic concentrations. This study introduces a novel strategy for fabricating a PbO2 + Ag composite electrode with significantly improved OER activity and stability in a pH-neutral environment. Our results suggest that incorporating Ag as a surface additive improves the efficiency of utilizing adsorbed oxygenated species via the bridge-site-top-site pathway. Moreover, the surface decoration of Ag resulted in enhanced electrocatalytic stability by diverting the attack of oxygenated species to Pb thereby effectively preventing Pb dissolution. The results not only establish a method for utilizing PbO2 in pH-neutral OER applications, but also propose a potential strategy for employing less noble catalysts in cost-effective electrochemical energy conversions.

Superfast hydrous-molten salt erosion to fabricate large-size self-supported electrodes for industrial-level current OER

Durable, active, and cheap oxygen evolution reaction (OER) electrocatalyst to replace the noble metal-based ones is appealing but challenging in energy storage fields. Here, we devise a one-pot low-temperature hydrous molten salt erosion strategy to vertically root the thin and dense bimetal hydroxide (NiFeOxHy) nanosheet on commercial nickel foam in 1 min. The defect-rich nanosheets are interdigitated together to yield a highly porous array, which offers affluent exposed electroactive centers, decreased charge/mass transfer, and augmented mechanical stability, while a strong Ni-Fe synergy elicits the signal redox reactivity of both metal and nonmetal lattice oxygen. Due to such effects, the typical NiFeOxHy electrode accesses a catalytic current of 10 mA cm−2 at a low overpotential 216 mV for freshwater electrolyte and 232 mV for saline one both with a small Tafel slope of 53 mV dec−1, while stably working for 1000 h at 0.1 A cm−2 in freshwater electrolyte and over 550 h at 1 A cm−2 in saline one. This evidences efficient and stable large-current–density OER performance, particularly a strong Cl− anti-erosion. The large-scale NiFeOxHy electrode materials (81 cm2) with a commensurate performance are fabricated on nickel foam, heralding the enormous prospect for practical usage. This exceedingly procedure-, energy- and time-saving erosion tactic can be generalized to common metal foam substrates and hydrous metal molten salts, accenting a momentous stepping stone for integral construction of self-supported and large-size electrodes towards commercially-met OER application and beyond.

Cobalt-based CoSe/CoO heterostructure: A catalyst for efficient oxygen evolution reaction

Hydrogen is known as the fuel for 21st century, the best and clean method to produce hydrogen is electrolysis of water. The oxygen evolution reaction (OER) is of vital position in water splitting, enabling the production of clean hydrogen fuel and contributing to renewable energy solutions. However, the inherently sluggish nature of the OER presents a major challenge for practical water electrolysis but at the same time electrocatalysts play a pivotal role by overcoming this challenge through accelerating the reaction kinetics and reducing the energy requirements. In the realm of electrocatalysts for OER, cobalt-based materials have gained significant attention due to their low overpotential and cost-effectiveness. Among prepared catalysts, the CoSe/CoO heterostructure has emerged as a standout performer, offering an optimal balance of efficiency and minimal overpotential. This electrocatalyst exhibits exceptional electrochemical performance, featuring a low 1.31 V onset potential (vs. RHE) and a mere 170 mV overpotential at a current density of 40 mA/cm2 for OER, setting a new standard for Co-based catalysts. Moreover, the CoSe/CoO heterostructure surpasses Co based bench mark electrocatalysts by displaying the lowest overpotential. Moreover, when subjected to controlled potential electrolysis at 1.65 V (vs. RHE) with a stable current density of 60 mA/cm2, it showcases remarkable electrochemical stability, affirming its practicality for real-world applications. The hydrothermal synthesis of CoSe, CoO, and their heterostructure (CoSe/CoO) represents a straightforward and accessible approach, rendering them as promising candidates for water splitting, specifically in the context of oxygen evolution. These outstanding results achieved with non-precious metal electrocatalysts open new avenues for practical OER applications, providing a platform for the scientific community to advance the development of effective electrocatalysts using non-noble metals in the field of electrochemical water splitting.

Perovskite CoSn(OH)6 nanocubes with tuned d-band states towards enhanced oxygen evolution reactions.

The CoSn(OH)6 perovskite hydroxide is a structure stable and inexpensive electrocatalyst for the oxygen evolution reaction (OER). However, the OER activity of CoSn(OH)6 is still unfavorable due to its limited active sites. In this work, an Fe3+ doping strategy is used to optimize the d-band state of the CoSn(OH)6 perovskite hydroxide. The CoSn(OH)6 catalyst with slightly Fe3+ doped nanocubes is synthesized by a facile hydrothermal method. Structure characterization shows that Fe3+ ions are incorporated into the crystal structure of CoSn(OH)6. Owing to the regulation of the electronic structure, CoSn(OH)6-Fe1.8% exhibits an OER overpotential of 289 mV at a current density of 10 mA cm-2 in OER electrochemical tests. In situ Raman spectroscopy shows that no obvious re-construction occurred during the OER for both CoSn(OH)6 and CoSn(OH)6-Fe1.8%. DFT calculations show that the introduction of Fe3+ into CoSn(OH)6 can shift the d-band center to a relatively high position, thus promoting the OER intermediates' adsorption ability. Further DFT calculations suggest that incorporation of an appropriate amount of Fe3+ into CoSn(OH)6 significantly reduces the rate-determining Gibbs free energy during the OER. This work offers valuable insights into tuning the d-band center of perovskite hydroxide materials for efficient OER applications.

Exploring the potential of cobalt hydroxide and its derivatives as a cost-effective and abundant alternative to noble metal electrocatalysts in oxygen evolution reactions: a review

Exploration of various cobalt-based hydroxides for oxygen evolution reaction applications.

N-doped defect-rich porous carbon nanosheets framework from renewable biomass as efficient metal-free bifunctional electrocatalysts for HER and OER application

In response to the demand for clean, renewable energy sources and storage technologies, innovative materials and combinations have been developed at reasonable prices as effective electrode materials. Current research and development of carbon-based metal-free catalysts have opened up new research areas for bifunctional electrocatalysts for overall water splitting. Herein, we developed N-self-doped defect-rich porous carbon nanosheets derived from platycladus orientalis tree-cone biomass for overall water splitting. The developed N-self-doped defect-rich porous carbon nanosheets have large surface areas (3369 m2/g), high pore volumes (2.1 cm3 g−1), and high electrical conductivities (12.69 S/cm). N-self-doped defect-rich porous carbon nanosheet framework was employed in water splitting as a dual function in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Electrodes fabricated from the KOH-II ABC nanosheets show excellent OER and HER performances in the 0.5 M H2SO4 solution. The current density of 10 mA cm−2 is reached at a low overpotential of 90 mV for OER and 188 mV for HER. In addition, KOH-II ABC nanosheets also show a remarkable performance on overall water splitting, which only required a cell voltage of 1.49 V to reach current densities of 10 mA cm−2 in 0.5 M H2SO4 solution. The presence of defects in the carbon nanosheets, higher specific surface area, excellent electrochemical active surface area and N doping effectively enhance the reaction kinetics for attaining efficient OER and HER performances. This facile approach to preparing biomass-derived N-doped defect-rich porous carbon materials empowers next-generation green fuel conversion technologies for carbon neutrality.

Nitrogen-Doped CuO@CuS Core-Shell Structure for Highly Efficient Catalytic OER Application.

Water electrolysis is a highly efficient route to produce ideally clean H2 fuel with excellent energy conversion efficiency and high gravimetric energy density, without producing carbon traces, unlike steam methane reforming, and it resolves the issues of environmental contamination via replacing the conventional fossil fuel. Particular importance lies in the advancement of highly effective non-precious catalysts for the oxygen evolution reaction (OER). The electrocatalytic activity of an active catalyst mainly depends on the material conductivity, accessible catalytically active sites, and intrinsic OER reaction kinetics, which can be tuned via introducing N heteroatoms in the catalyst structure. Herein, the efficacious nitrogenation of CuS was accomplished, synthesized using a hydrothermal procedure, and characterized for its electrocatalytic activity towards OER. The nitrogen-doped CuO@CuS (N,CuO@CuS) electrocatalyst exhibited superior OER activity compared to pristine CuS (268 and 602 mV), achieving a low overpotential of 240 and 392 mV at a current density of 10 and 100 mA/cm2, respectively, ascribed to the favorable electronic structural modification triggered by nitrogen incorporation. The N,CuO@CuS also exhibits excellent endurance under varied current rates and a static potential response over 25 h with stability measured at 10 and 100 mA/cm2.