We designed a novel Ru-doped NiO/Co3O4 heterostructure as the catalyst to achieve superior OER, ORR, and HER activity. The synergistic interaction of Ru doping and NiO/Co3O4 heterostructure could ...substantially optimize the overall electrochemical active area, conductivity and activation energy of the catalyst, resulting in excellent catalytic performance.
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•Ru-doped NiO/Co3O4 owns multiple active centers and strong synergistic effect.•The adjustment of electronic energy states by Ru doping and thus the influence of catalytic performance is revealed.•Such features allow Ru-doped NiO/Co3O4 with superior OER/ORR/HER catalytic activity in alkaline media.•Ru-doped NiO/Co3O4 catalyst has an ultralow overpotential for OER and a high half-wave potential for ORR.•Ru-doped NiO/Co3O4 based water-splitting device only needs 1.555 V and 1.650 V to reach 10 and 100 mA cm−2.
The development of cheap and efficient OER/ORR/HER electrocatalysts is important to promote green energy conversion and storage technologies. Experimental results show that the synergistic effect of Ru doping and NiO/Co3O4 heterostructure can significantly improve the catalytic activity. The existence of NiO/Co3O4 heterostructure, the appropriate proportion of Ru (only 2%) and the proper electronic energy state tuning are determined by electronic detection and elemental analysis, which enhanced the activation energy, electrical conductivity and electrochemical active surface area of the catalyst. Thus, the Ru-doped NiO/Co3O4 heterostructure exhibits superior OER/ORR/HER performance, reaching 100 mA cm−2 in alkaline electrolytes at only 138 mV (HER) and 269 mV (OER) overpotential, and a high half-wave potential of 0.88 V (ORR). The water-splitting device assembled by the catalyst can operate stably for a long time (>40 h), better than Pt/C and RuO2 at high current densities.
The development of efficient and cost-effective electrocatalysts for hydrogen evolution reaction (HER) is an urgent requirement but formidable challenge. In this work, Co and Mn were introduced into ...self-supported nickel-vanadium layered double hydroxide (NiV–LDH) to modulate electronic structure. The introduced Co and Mn can induce electron transfer among various cations to modulate the electronic structure, exerting a positive influence on the catalytic activity of HER. As a results, the samples with Co (NiVCo–LDH) and Mn (NiVMn–LDH) exhibits excellent HER activity. To achieve a current density of 10 mA cm–2 in 1.0 M KOH, NiVCo–LDH and NiVMn–LDH requiring overpotential of 135 mV and 123 mV, respectively. In contrast, NiV–LDH needed an overpotential of 198 mV to reach the same current density. The ideal performance of NiVCo–LDH and NiVMn–LDH offer a potential application in non-noble metal-based industrial electrolytic water splitting to produce high-purity hydrogen.
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Abstract
Efficient molecular oxygen activation is crucial for catalytic oxidation reaction, but highly depends on the construction of active sites. In this study, we demonstrate that dual adjacent Fe ...atoms anchored on MnO
2
can assemble into a diatomic site, also called as MnO
2
-hosted Fe dimer, which activates molecular oxygen to form an active intermediate species Fe(O = O)Fe for highly efficient CO oxidation. These adjacent single-atom Fe sites exhibit a stronger O
2
activation performance than the conventional surface oxygen vacancy activation sites. This work sheds light on molecular oxygen activation mechanisms of transition metal oxides and provides an efficient pathway to activate molecular oxygen by constructing new active sites through single atom technology.
Transition metal oxides are nowadays one of the most important materials in the manufacture of capacitive electrodes. The most important problems with these materials for applied energy storage ...devices are low specific energy and poor electrical conductivity. In this research nickel ferrite nanoparticles (NiFe2O4) and also hybrid of NiFe2O4/rGO are synthesized by hydrothermal method and characterized by XRD, Raman, and XPS analysis. The amount of porosity and specific surface area is studied by BET analysis as and surface morphology is studied by SEM and TEM. To investigate the effect of adding rGO to NiFe2O4 nanoparticles, from a hybrid electrode superconducting electrochemical tests are performed, including CV, EIS, and charge-discharge. This electrode with a capacitance of 584.63 F/g and capacitance retention of 91% after 2000 consecutive cycles can be a tempting option for supercapacitor applications.
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•Synthesis of NiFe2O4/rGO by the hydrothermal method.•Electrochemical reactions occur during a diffusion-controlled process.•NiFe2O4/rGO shows a great capacitance retention of 91% after 2000 cycles.
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An ever-increasing market for electric vehicles (EVs), electronic devices and others has brought tremendous attention on the need for high energy density batteries with reliable ...electrochemical performances. However, even the successfully commercialized lithium (Li)-ion batteries still face significant challenges with respect to cost and safety issues when they are used in EVs. From a cathode material point of view, layered transition-metal (TM) oxides, represented by LiMO2 (M = Ni, Mn, Co, Al, etc.) and Li-/Mn-rich xLi2MnO3·(1–x)LiMO2, have been considered as promising candidates because of their high theoretical capacity, high operating voltage, and low manufacturing cost. However, layered TM oxides still have not reached their full potential for EV applications due to their intrinsic stability issues during electrochemical processes. To address these problems, a variety of surface modification strategies have been pursued in the literature. Herein, we summarize the recent progresses on the enhanced stability of layered TM oxides cathode materials by different surface modification techniques, analyze the manufacturing process and cost of the surface modification methods, and finally propose future research directions in this area.
As a main oxidizer in solid composite propellants, ammonium perchlorate (AP) plays an important role because its thermal decomposition behavior has a direct influence on the characteristic of solid ...composite propellants. To improve the performance of solid composite propellant, it is necessary to take measures to modify the thermal decomposition behavior of AP. In recent years, transition metal oxides and carbon-supported transition metal oxides have drawn considerable attention due to their extraordinary catalytic activity. In this review, we highlight strategies to enhance the thermal decomposition of AP by tuning morphology, varying the types of metal ion, and coupling with carbon analogue. The enhanced catalytic performance can be ascribed to synergistic effect, increased surface area, more exposed active sites, and accelerated electron transportation and so on. The mechanism of AP decomposition mixed with catalyst has also been briefly summarized. Finally, a conclusive outlook and possible research directions are suggested to address challenges such as lacking practical application in actual formulation of solid composite propellant and batch manufacturing.
In article number 1600488, Gerbrand Ceder and co‐workers present a computational high‐throughput approach to identify novel disordered oxides for high‐capacity Li‐ion battery cathodes. The image ...shows the structures of ordered and cation‐disordered Li transition metal (TM) oxides. Various TM combinations, predicted to form either ordered or disordered phases are visualized as small and large circles, respectively.
Summary
First‐generation sodium‐ion batteries (SIBs) are commercially launched by Faradion Ltd., UK, and HiNa Battery Technology Company Ltd., China, utilizing the transition metal oxide‐based ...cathodes. Currently, the commercial Faradion cells deliver ~1000 cycles at an energy density of ~140 to 150 Wh kg−1, whereas HiNa SIB cells deliver ~120 Wh kg−1. P2‐type, O3‐type, and composite P‐O and P‐P type transition metal oxide cathodes have generated much interest in the last few years. P2‐type layered oxides are critical as cathodes in achieving higher energy and power density in SIB technology, along with better C‐rate capabilities. Compared to their O3‐type counterparts, P2‐type layered transition metal oxides encounter lower activation energy barriers, enabling improved rate kinetics. However, P2‐type cathodes often face poor cycle stability due to undesirable phase changes during charge‐discharge cycles and structural instability to air and moisture. This review evaluates all the P2‐type layered oxide compounds as SIB cathodes, highlighting the strategies followed to meet the challenges and offers aspects of their successful commercialization.
Insights into the prospects of P2‐type transition metal oxides as commercial cathodes for SIBs depend on sodium stoichiometry, high‐voltage phase transitions, anionic O2 redox at high potentials, and transition‐metal ion substitution to improve the specific capacity, cycle life, and rate capabilities of SIBs. The review comprehensively follows the structural evolution of P2‐type oxides from single‐metal oxide to quadra‐metal oxides in improving their cathode performance in non‐aqueous sodium‐ion batteries (SIB).
In this study, Cu0·5Mn0·5Fe2O4 nanoparticles were synthesized through a facile coprecipitation process, evaluated as highly efficient photo-Fenton catalyst for removal of bisphenol A (BPA). Benefit ...for its larger surface area and unique chemical composition, the Cu0·5Mn0·5Fe2O4 catalyst exhibited superior catalytic activity toward the degradation of BPA, with a rate constant values ranging from 0.247 to 1.090 min−1 based on different operating parameters (catalyst load, initial solution pH, H2O2 concentration and reaction temperature). Importantly, an excellent BPA removal efficiency exceeding 95.2% were obtained after eight successive runs of photo-Fenton process. Electron paramagnetic resonance (EPR) spectroscopy and radical scavenger experiments demonstrated that the hydroxyl radical was the dominant radical in degradation of BPA. A possible BPA degradation pathway was proposed according to the detected intermediates by GC-MS and HPLC. In brief, this work is expected to provide a new heterogeneous photo-Fenton catalyst for the organic pollutants removal from wastewater.
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•Cu0.5Mn0.5Fe2O4 was successfully synthesized by a facile method.•Photo-Fenton system showed high performance for BPA degradation.•Hydroxyl radical was identified critical for BPA degradation.•Degradation mechanism and reusability were studied in detail.•Possible BPA degradation pathways were proposed.
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