High Catalytic Activity Research Articles

Ag‐Based Bimetallic Nanoparticles for the Catalytic Reduction of Nitrophenol and Organic Dyes: An Overview

AbstractBimetallic nanoparticles with synergistic effects revealed much higher catalytic activity than respective monometallic materials. This review describes bimetallic nanoparticles, especially silver nanoparticles, combined with the other transition elements, such as Ag−Fe, Ag−Co, Ag−Ni, and Ag−Cu, as an enhanced catalytically active material. The coverage is given to the various methods of preparation, in which factors responsible for different structures of bimetallic nanoparticles are thoroughly discussed. Lastly, we explore the use of bimetallic nanoparticles as a catalyst for the degradation of numerous organic pollutants that contribute to water pollution.

The Effect of Weakly Coordinating Solvent and Counter Anion on Diphosphine‐Palladium(II) Catalytic Reactivity for Copolymerization of 1‐Butene with Carbon Monoxide in Aqueous Media

AbstractWater soluble bis(acetonitrile) diphospalladium (II) complexes cis‐[Pd(L1–L5)(NCCH3)2][BF4]2 (C1–C5) were obtained by the reaction [Pd(NCCH3)4][BF4]2 with diphosphines ligands L1–L5 (CH2(CH2PR2)2: where R=(CH2)nP(O)(OEt)2, n=2–4, n=6 and n=8)) in dichloromethane–acetonitrile. The isolated complexes were characterized by elemental analysis, FTIR, 1H‐ and 31P‐NMR spectroscopy. The complexes were applied as catalysts for the copolymerization of 1‐butene with carbon monoxide in aqueous media. The present work emphasized on the effect of weakly coordinated solvent and counterion on the catalytic behavior of cis‐[Pd(L1–L5)(NCCH3)2][BF4]2 complexes compared to previously prepared cis‐[ Pd(L1–L5)(OAc)2] (A1–A5). The exchange of π‐bonding NCCH3 ligand with π‐bonding CO and alkene was more favored than the exchange of σ‐bonding OAc− as reflected by the much higher catalytic activity (TON) of the former compared to the latter. In order to compare the catalytic efficiency of water soluble complexes with the performance of a standard, the water insoluble complex, cis‐[Pd(CH2(CH2P(CH2CH3)2)2(NCCH3)2][BF4]2, C6, was prepared and incorporated in the investigations. The isolated alternating 1‐butene/CO copolymer exhibits glass transition temperature of Tg=−3–−15 °C, which is in the range desirable for latex emulsion application. The solid content is up to 21 % with high molecular weight (Mw=4×104 g mol−1) and narrow polydispersities (Mw/Mn=2–3). The C5 complex was found to be fourteen times more active in aqueous polymerization medium (6369 mol substr. mol Pd−1 h−1) than C6 complex in nonaqueous medium (441 mol substr. mol Pd−1 h−1).

Ag-doped CuO nanoparticles embedded reduced graphene oxide nanocomposite from Punica granatum peel extract and evaluation of their photocatalytic activity and antimicrobial potential

The present study explored Punica granatum peel extract as a reducing and capping agent for synthesis of Ag-doped CuO nanoparticles embedded reduced graphene oxide (rGO) nanocomposite. The crystalline nature of the Ag doped CuO/rGO was identified utilizing X-ray diffraction (XRD) analysis. The surface morphology of Ag doped CuO/rGO was investigated by Scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. The surface elemental composition of the prepared material was investigated by the Energy dispersive spectra (EDS) analysis. Ag resulted in enhanced absorbance in the visible range as well as a reduction in band gap energy. The catalytic activity of the green synthesized Ag doped CuO/rGO photocataltyst was evaluated in the reduction of organic pollutants such as 4-nitrophenol (4-NP) and methylene blue (MB) in water at mild conditions. The results indicated that the biosynthesized Ag-CuO/rGO composites have very high and effective catalytic activity over MB dye (99.5 %), high rate constant (0.9871 min−1) and long term stability with 60 min irradiation of UV light. In addition, initial process parameters of catalyst dosage and MB concentration, and pH of the solution were also examined. Differential antimicrobial effects of doped and undoped CuO nanoparticles (NPs) against selected strains of bacteria and fungi were confirmed.

Common methodologies for treating environmental issues with nanomaterials

With rapid industrialisation and population growth, the Earths ecological environment now confronts increasingly complex and diverse challenges. Traditional pollution treatment methods, such as activated sludge for sewage and electrostatic precipitation for air pollution, can effectively manage most environmental pollution. However, some pollutants (e.g. metals, organic dyes, gaseous trace pollutants in heavy water) either cannot be addressed by conventional methods or are prohibitively expensive. Hence, there is a pressing need to develop new environmental technologies. The emergence and development of nanotechnology and nanoscience present novel opportunities for environmental governance, as nanomaterials offer advantageous traits such as high specific surface area, catalytic activity, and photocatalytic activity. This renders nanomaterials better adsorbents, catalysts, and sensors compared to traditional materials. This article examines three methods - adsorption, filtration, and degradation - through which nanomaterials can be utilised to address environmental challenges, and the advantages and disadvantages of such methods are discussed. Finally, this article provides insights in response to the findings presented.

Tuning the thermo-mechanical synergies effect of solid oxide fuel cells with negative thermal expansion NdMnO3 in La0.6Sr0.4Co0.2Fe0.8O3-δ-based symmetric electrode

Solid oxide fuel cells (SOFCs) are efficient and clean energy conversion devices, but one of the major challenges for their marketization is the instability of different component materials under high temperature operating conditions. The existence of a certain internal stress gradient between materials with different thermal expansion characteristics in the process of SOFCs from low temperature assembly to high temperature use is the main reason of this instability, leading to the inability of SOFCs to repeat start-stop and the rapid decay of long-term stability performance. To improve these problems, a creative concept of fuel cell interface overall regulation is proposed, simplifying the complex interface between different components of SOFCs into a unified and adjustable quasi-zero difference thermal expansion interface. The composite of high catalytic activity electrode material and high stability negative thermal expansion material is used for electrolyte support structure symmetrical cell, which makes the whole cell “sandwich” structure thermally and mechanically compatible. As a concept verification, the classic high catalytic performance electrode material La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF), Gd0.2Ce0.8O2-δ (GDC) and NdMnO3 (NM) negative thermal expansion material with high chemical stability and mechanical stability were composited in equal proportions to form LSCF@GDC&NM electrode as the symmetrical electrode. After equal proportion compositing, the thermal expansion curve of LSCF@GDC&NM material can highly coincide with the thermal expansion curve of GDC, making the single cell with LSCF@GDC&NM electrode can withstand 25 power thermal cycles without significant performance decay, achieving 442 mW cm−2 at 800 °C and maintaining stably for 140 h without any degradation. These results show that using negative thermal expansion material to regulate electrode strategy is expected to make a whole zero difference thermal fuel cell configuration.

SYNTHESIS OF Ag-MODIFIED TiO2 SOL-GEL FILMS AND ITS APPLICATION AS PHOTOCATALYSTS FOR METHYLENE BLUE DEGRADATION

In the study, the photocatalytic activity of TiO2 films that are created by dip-coating from a sol that contained titanium (IV) isopropoxide, monoethanolamine, and 2-methoxyethanol is demonstrated. Through photo-fixation of Ag (I) ions with varied concentration (10-2 - 10-4 M) in the water phase under UV illumination, the films are subsequently surface-modified with Ag co-catalyst layers. Scanning Electron Microscopy (SEM), X-Ray Photoelectron Spectroscopy (XPS), Ultraviolet-Visible (UV) Spectroscopy, and Electron Paramagnetic Resonance (EPR) techniques are used to physically characterize the samples. Results reveal that the modification of the co-catalyst had no impact on the thickness and porosity of the films. In addition, the study show that the modified TiO2 films had increased photocatalytic activity. All the characterization methods used have shown the formationof surface - bound Ag (I) species and metallic silver nanoclusters. By measuring the Methylene Blue (MB) dye degradation under UV light illumination, as - prepared and Ag -modified TiO2 films are evaluated for their photocatalytic activity, and the impact of the silver precursor concentration during photo-fixation is investigated.The highest catalytic activity is seen for films that have been modified at a concentration of Ag (I) of 10-2 M. Ordered from highest to lowest, the MB photodegradation rate constants are TiO2 < TiO2 /Ag, 10-4 < TiO2 /Ag, 10-3 < TiO2 / Ag, 10-2.

A New Approach in Lipase-Octyl-Agarose Biocatalysis of 2-Arylpropionic Acid Derivatives.

The use of lipase immobilized on an octyl-agarose support to obtain the optically pure enantiomers of chiral drugs in reactions carried out in organic solvents is a great challenge for chemical and pharmaceutical sciences. Therefore, it is extremely important to develop optimal procedures to achieve a high enantioselectivity of the biocatalysts in the organic medium. Our paper describes a new approach to biocatalysis performed in an organic solvent with the use of CALB-octyl-agarose support including the application of a polypropylene reactor, an appropriate buffer for immobilization (Tris base-pH 9, 100 mM), a drying step, and then the storage of immobilized lipases in a climatic chamber or a refrigerator. An immobilized lipase B from Candida antarctica (CALB) was used in the kinetic resolution of (R,S)-flurbiprofen by enantioselective esterification with methanol, reaching a high enantiomeric excess (eep = 89.6 ± 2.0%). As part of the immobilization optimization, the influence of different buffers was investigated. The effect of the reactor material and the reaction medium on the lipase activity was also studied. Moreover, the stability of the immobilized lipases: lipase from Candida rugosa (CRL) and CALB during storage in various temperature and humidity conditions (climatic chamber and refrigerator) was tested. The application of the immobilized CALB in a polypropylene reactor allowed for receiving over 9-fold higher conversion values compared to the results achieved when conducting the reaction in a glass reactor, as well as approximately 30-fold higher conversion values in comparison with free lipase. The good stability of the CALB-octyl-agarose support was demonstrated. After 7 days of storage in a climatic chamber or refrigerator (with protection from humidity) approximately 60% higher conversion values were obtained compared to the results observed for the immobilized form that had not been stored. The new approach involving the application of the CALB-octyl-agarose support for reactions performed in organic solvents indicates a significant role of the polymer reactor material being used in achieving high catalytic activity.

Study on Catalytic Activity of Synthetic Cobalt, Nickel and Copper Complexes due to Preferred Structures Determined by X‐Ray Crystallography for Methyl Methacrylate Polymerization

AbstractWe have designed and synthesized two novel pyridyl‐quinoxaline ligands, L1 and L2, as well as twelve cobalt, nickel, and copper complexes, 1–6 and 1 a–6 a. Unexpectedly, high regularities in the synthesis of both ligands and complexes were found. Further X‐ray diffraction analyses revealed that the two ligands had similar geometrical configurations, and the structures of twelve complexes were regularly divided into two categories: binuclear and mononuclear, which would be beneficial for elucidating structure‐activity relationships of metal catalysts. In addition, the experimental results showed significant variations in the catalytic performance of methyl methacrylate polymerization with different catalysts. Under the optimum reaction conditions, the mononuclear copper complex 3 a displayed a remarkably high catalytic activity of 2.76×105 g ⋅ mol−1 h−1, generating Poly(methyl methacrylate) with molecular weight of Mn=8.55×105 g ⋅ mol−1 and molecular weight distribution of Đ=1.67.This outcome suggested that copper had the potential to serve as a promising catalytic metal center.

Chromium Catalysts for Selective Ethylene Oligomerization Featuring Binuclear PNP Ligands.

A series of novel binuclear PNP ligands based on the cyclohexyldiamine scaffold were synthesized for this study. The experimental results showed that positioning the two PNP sites at the para-positions of the cyclohexyl framework led to a significant enhancement in the catalytic activity for selective tri/tetramerization of ethylene. The PNP/Cr(acac)3/MAO(methylaluminoxane) catalytic system exhibited relatively high catalytic activity (up to 3887.7 kg·g-1·h-1) in selective ethylene oligomerization with a total selectivity of 84.5% for 1-hexene and 1-octene at 40 °C and 50 bar. The relationship between the ligand structure and ethylene oligomerization performance was further explored using density functional theory calculations.

Mechanistic Insights into Electrocatalytic Hydrogen Evolution by an Exceptionally Stable Cobalt Complex.

Co(aPPy) is one of the most stable and active molecular first-row transition-metal catalysts for proton reduction reported to date. Understanding the origin of its high performance via mechanistic studies could aid in developing even better catalysts. In this work, the catalytic mechanism of Co(aPPy) was electrochemically probed, in both organic solvents and water. We found that different mechanisms can occur depending on the solvent and the acidity of the medium. In organic solvent with a strong acid as the proton source, catalysis initiates directly after a single-electron reduction of CoII to CoI, whereas in the presence of a weaker acid, the cobalt center needs to be reduced twice before catalysis occurs. In the aqueous phase, we found drastically different electrochemical behavior, where the Co(aPPy) complex was found to be a precatalyst to a different electrocatalytic species. We propose that in this active catalyst, the pyridine ring has dissociated and acts as a proton relay at pH ≤ 5, which opens up a fast protonation pathway of the CoI intermediate and results in a high catalytic activity. Furthermore, we determined with constant potential bulk electrolysis that the catalyst is most stable at pH 3. The catalyst thus functions optimally at low pH in an aqueous environment, where the pyridine acts as a proton shuttle and where the high acidity also prevents catalyst deactivation.

Salt assistant bimetallic sludge-derived porous carbon for efficient peroxymonosulfate activation

The development of cost-effective, environmentally benign, and high-performance peroxymonosulfate (PMS) activation towards wastewater treatment is still considered a challenge. In this work, the sludge-derived porous carbon loaded with bimetal oxides (DSC-FeMn) was fabricated by molten salt assistant strategy using the combination of zinc chloride, metal ions and Fe containing sludge. The obtained DSC-FeMn exhibited high catalytic activity for nearly 100 % 4-chlorophenol (4-CP) removal within 30 min with the k of 0.304 min−1, which was 1.07 and 11.94 times that of the single Fe and Mn-sludge-derived carbon (DSC-Fe, DSC-Mn), respectively. Quenching experiments, electron paramagnetic resonance tests (EPR), X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR) and electrochemical experiments proved that the radical pathway, dominated by OH and SO4−, led to the excellent degradation performance of DSC-FeMn, which was attributed to the redox cycling between Fe and Mn. This study provides a new idea for sludge resource utilization, and it deepens the understanding of the mechanism of PMS activation by the synergistic interaction between bimetal.

Work function-tunable graphene/WO3 heterojunctions for high-performance photoelectrochemical cell: UV-treatment effect and defective graphene

Designing hybrid photoelectrodes with graphene capable of efficient charge-carrier transfer and excellent chemical stability is an effective strategy for developing high-performance photoelectrochemical (PEC) cells. However, it remains unclear how the PEC properties are enhanced and how to control the junction properties in graphene/metal oxide heterojunction-based photoelectrodes. Here, we develop a deterministic junction to enhance PEC performance in graphene/tungsten trioxide (WO3)-based photoelectrodes by tuning the work function of graphene. It reveals that the band structure of graphene/WO3 heterojunctions can be modified by ultraviolet (UV) treatment on WO3 thin films. This modification is supported by the observation that a single-layer graphene/UV-treated WO3 photoelectrode exhibits significantly enhanced PEC activities toward the oxygen evolution reaction (OER) (evidenced by features like a threefold increase in photocurrent, an onset potential shift, and improved stability), whereas the single-layer graphene/untreated WO3 electrode demonstrates improved properties for the hydrogen evolution reaction (HER). Additionally, defects in the graphene layer formed during PEC water splitting contribute to high catalytic activities of the graphene/WO3 photoelectrode due to a decrease in the Gibbs free energy for OER and HER. These results emphasize that band structure engineering via work function tuning in graphene/WO3 heterostructures can provide multiple benefits for high PEC performance and long-term stability.

Bimetallic PtZn nanoparticles anchored in high-silica SSZ-13 zeolite for efficient propane dehydrogenation

Direct dehydrogenation of propane to propylene (PDH) is a promising route to meet the ever-growing global propylene demand, but the industrial Pt-based catalysts usually suffer from serious deactivation derived from coke deposition and sintering under harsh reaction conditions. In this work, PtZn bimetallic nanoparticles encapsulated into high-silica SSZ-13 zeolites (PtZn@SSZ-13) were synthesized via a facile ligand-protected interzeolite transformation strategy. In a PDH reaction, the synthesized 0.5Pt3Zn@SSZ-13 catalyst exhibits superior catalytic performance with a propane conversion of 23.7% and a propylene selectivity of 96.8%, which is significantly better than that of PtZn supported on high-silica SSZ-13 (0.5Pt3Zn/SSZ-13). Particularly, the high catalytic activity of this catalyst can be kept during three successive oxidation–reduction cycles. Detailed characterizations including HAADF-STEM, XPS, UV–Vis, H2-TPR reveal that the remarkable improvement of PDH performance is attributed to the PtZn synergistic effect as well as the confinement of SSZ-13 zeolites. The DFT calculations and microkinetic simulations also evidenced that the Pt particles anchored on the Zn-doped SSZ-13 zeolite pore framework possessed obviously higher propane dehydrogenation activity, whereas the anti-coking ability of 0.5Pt3Zn@SSZ-13 was also stronger than Pt (111) surface, demonstrating the superior performance of 0.5Pt3Zn@SSZ-13.

Nickel-hydroxide decorated trimanganese-tetroxide nanorods supported on graphene as bifunctional electrocatalyst for metal–air batteries

Manganese oxide, such as Mn3O4, is one of promising material as electrocatalyst in air–cathode for metal–air battery due to low cost, high catalytic activity and good stability. Although pure Mn3O4 material exhibits excellent catalytic activity to ORR, it is severely limited by its intrinsically low conductivity and high over-potential toward OER. In this work, the hybrid materials of nickel-hydroxide-decorated nanorods of trimanganese-tetroxide supported on reduced-graphene have been prepared by one-step hydrothermal method. The composite materials are used as bifunctional cathode catalysts to ORR/OER, and investigated by the technologies of rotating disk electrode and metal–air batteries. The results indicate that the hybrid material of Mn-Ni/rGO use as catalyst in air–cathode for Al/Zn–air battery has good catalytic activity. Based on analysis of scanning electron microscope and X-ray photoelectron spectroscopy, the composite material shows good performance owing to the improvement of conductivity supported on graphene, more Mn4+ on the surface of hybrid material, the coexistence of Mn3+/Mn4+ redox couple, and the synergism between nickel-hydroxide and graphene.

Substitutional phosphorus doping stimulates strong metal-support interactions for anion exchange membrane based alkaline seawater electrolysis

The development of electrocatalysts with high catalytic activity and resistant to chlorine has become crucial for the large-scale implementation of seawater electrolysis. Here, the strong metal support interaction (SMSI) between Pt and NiMoO4 is enhanced by substitutional P atom-doping (P-Pt/NiMoO4@NF) to optimize the metal surrounding environment, realizing the efficient and anticorrosive seawater electrolysis. Density functional theory (DFT) reveals that substitutional P atom-doping can adjust the electronic structure to optimize the hydrogen adsorption free energy (ΔGH*) and decrease the adsorption energy of Cl- for the HER process. Benefiting from the SMSI caused by substitutional P atom-doping, the prepared P-Pt/NiMoO4@NF catalyst achieves a current density of 1.0 A cm−2 at an ultra-low overpotential of only 80 mV, surpassing the most reported Pt-based electrocatalysts. More importantly, in the anion exchange membrane (AEM) electrolyzer, the catalyst used as the cathode can drive 500 mA cm−2 under industrial conditions with only 1.75 V, while running steadily for 120 h, and with high efficiency and low price of H2 per gallon gasoline equivalent (GGE).

Selective electrocatalytic oxidation of ammonia to nitrogen by using titanium dioxide nanorod array decorated with ultrasmall Ir nanoparticles and non-noble metal Fe nanoparticles

Electrochemical ammonia oxidation process through active chlorine has been proposed as a potentially effective method for ammonia removal. Currently, most of the anodes require to use high-stable TiO2 loaded with large particles of noble metal Ru or Ir, which have low activity and high cost. Herein, we prepare ultrasmall and uniform metal nanoparticles of Ir on TiO2 to remove ammonia. Moreover, we use non-noble metal Fe to replace noble metals. The ammonia removal efficiency of Fe/TiO2 under 2 VVS Ag / AgCl during 2 h is 100 % and 94 % of ammonia is converted to N2. The Fe/TiO2 anodes not only have higher catalytic activity but also show excellent stability and reusability. Fe/TiO2 anodes still exhibit excellence activity and selectivity after 1 year. As a common metal, Fe will have more application space than iridium in ammonia removal for its low cost and selectively high efficiency.

Highly dispersed cobalt clusters/nanoparticles embedded in cellulose nanocrystal derived carbon aerogel as efficient sulfur host for high performance lithium sulfur batteries

Exploring multifunctional sulfur host materials with high immobilization ability and catalytic activity is of great significance for realizing high-performance Lithium-sulfur (Li–S) batteries. Recently, cellulose nanocrystals (CNCs) receive extensive attention for advanced energy storage applications owing to their intrinsically exceptional physical/chemical properties and natural abundance. Herein, a highly dispersed cobalt clusters/nanoparticles embedded into CNC derived carbon aerogel composite (CA/Co-2) is for the first time synthesized. Benefiting from the interconnected hierarchical porous structure, homogeneously anchored Co clusters/nanoparticles and N-doped species, the designed CA/Co-2 could enable rapid electron/ion transport, efficient sulfur utilization, effective suppression of the shuttle effect and fast catalytic conversion of polysulfides, thereby contributing to outstanding electrochemical performance. Consequently, CA/Co-2@S cathode delivers high initial discharge capacity (1553.1 mAh g−1 at 0.1C) and superior cycle stability. Moreover, a remarkable rate performance of 681.4 mAh g−1 at 5.0C and exceptional long-term cycling stability with an ultralow capacity decay of 0.028 % per cycle at 5.0C over 1000 cycles could be achieved when coupled with carbon paper interlayer. This work develops a workable strategy for fabricating multifunctional sulfur host derived from the fascinating bio-nanomaterial of CNC, which provides valuable guidance for the future design of high-performance Li–S batteries.

Constructing 3D sandwich-like structured Ti foam/TiO2−x/SnO2-Sb composite electrodes for the degradation of PPCPs

The fabrication of Sb-doped SnO2 electrode with high catalytic activity and excellent durability for decomposition PPCPs (Pharmaceuticals and personal care products, PPCPs) is challenging. Herein, a Ti3+/Ovs-related TiO2−x is prepared by short-time annealing at low temperature in mixed gas with Zr as a cocatalyst. DFT calculations indicate that the introduction of Ti3+/Ovs defects could promote the formation of more ·OH. Then, the nanoflower rod-like SnO2-Sb catalytic layer supported on dual-defects TiO2−x is successfully synthesized by one-step pulse electrodeposition (PLED) combined with hydrothermal methods (H). This newly pulse electrodeposition technique solves the short lifetime problem of SnO2-Sb nanoflower electrodes current hydrothermal-based methods. 1O2 and ·OH are found to be the primary reactive oxygen species (ROSs) by radical quenching tests and electron paramagnetic resonance analysis. The optimized Ti foam/TiO2−x /SnO2-Sb electrode could degrade over 96.3 % of 20 mg L−1 amoxicillin (AMX) within 30 min, corresponding kinetic constant 0.10228 min−1. This will provide inspiration for the construction of defect engineering and new insights for the development of low-cost and high electrooxidation activity Sb-doped SnO2 electrode.

Coupling interface constructions of flower-like structure MoSe2–NiWSe2 for efficient oxygen evolution reaction and urea oxidation reaction

Because of its low thermodynamic voltage, the electrocatalytic urea oxidation reaction (UOR) is an effective way to replace the sluggish oxygen evolution reaction (OER) and address the issue of urea-rich water pollution. Herein, we have synthesized MoSe2–NiWSe2 with spherical nanoflower structure consisting of MoSe2 nanosheets and NiWSe2 nanosheets crisscrossed longitudinally and transversely. The results show that the prepared MoSe2–NiWSe2 has a significant competitive advantage in the UOR and OER. With 10 mA cm−2, a mere 200 mV overpotential was required, indicating high OER catalytic activity. MoSe2–NiWSe2-driven UOR might operate at a comparatively low potential of 1.36 V (10 mA cm−2). The overpotential did not significantly alter after 40 h of continuous operation, suggesting it possesses high UOR stability. A built-in electric field that aids in controlling the adsorption and oriented distribution of urea molecules and thus promotes the oxidative properties of water and urea forms at the interface of MoSe2 and NiWSe2, where the difference in electronegativity between the elements Mo and Ni induces self-driven charge transfer and interfacial coupling effects. This work offers a method for creating catalysts that produce more oxygen and clean up urea-rich water contamination.

Chemical etching to boost medium-entropy metal oxide for oxygen evolution reaction in alkaline

It is crucial to improve the catalytic activity of medium-entropy materials by adjusting the surface electronic structure of medium-entropy materials. In this research, we utilize a chemical etching method for synthesizing a medium-entropy metal oxide E-FeCoNiZn with abundant defects. Owing to the etching of Zn, a special form of electron-transfer by means of electron-accepting-donating is introduced, which greatly optimizes OER activity. The E-FeCoNiZn displays a superior OER activity with a low overpotential of 259 mV at 10 mA cm−2 and a small Tafel slope of 37.1 mV dec-1 in 1 M KOH solution, outperformingtheperformanceofFeCoNiZn and Ni-foam,whilemaintainingexcellentstabilityover48 h. Theoretical calculations demonstrate that the introduction of defects regulates the surface electronic structure of the E-FeCoNiZn via modifying the number of electrons transferred and then optimize the OER activity. Thisworkprovidesa newstrategyfordesigning medium-entropy materials possessing high catalytic activity.