Engineering the crystal structure of Pt-M (M = transition metal) nanoalloys to chemically ordered ones have drawn increasing attention in oxygen reduction reaction (ORR) electrocatalysis due to their high resistance against M etching in acid. Although Pt-Ni alloy nanoparticles (NPs) have demonstrated respectable initial ORR activity in acid, their stability remains a big challenge due to the fast etching of Ni. In this work, sub-6 nm monodisperse chemically ordered L1 0 -Pt-Ni-Co NPs are synthesized for the first time by employing a bifunctional core/shell Pt/NiCoO x precursor, which could provide abundant O-vacancies for facilitated Pt/Ni/Co atom diffusion and prevent NP sintering during thermal annealing. Further, Co doping is found to remarkably enhance the ferromagnetism (room temperature coercivity reaching 2.1 kOe) and the consequent chemical ordering of L1 0 -Pt-Ni NPs. As a result, the best-performing carbon supported L1 0 -PtNi 0.8 Co 0.2 catalyst reveals a half-wave potential (E 1/2 ) of 0.951 V vs. RHE in 0.1 M HClO 4 with 23-times enhancement in mass activity over the commercial Pt/C catalyst along with much improved stability (no performance degradation and Ni/Co loss in 5000 potential cycles). Density functional theory (DFT) calculations suggest that the L1 0 -PtNi 0.8 Co 0.2 core could tune the surface strain of Pt shells towards optimized Pt-O binding energy and facilitated reaction rate, thereby improving the oxygen reduction electrocatalysis.Received: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff))
As an anode material for sodium-ion batteries (SIBs), hard carbon (HC) presents high specific capacity and favorable cycling performance. However, high cost and low initial Coulombic efficiency (ICE) of HC seriously limit its future commercialization for SIBs. A typical biowaste, mangosteen shell was selected as a precursor to prepare low-cost and high-performance HC via a facile one-step carbonization method, and the influence of different heat treatments on the morphologies, microstructures, and electrochemical performances was investigated systematically. The microstructure evolution studied using X-ray diffraction, Raman, Brunauer–Emmett–Teller, and high-resolution transmission electron microscopy, along with electrochemical measurements, reveals the optimal carbonization condition of the mangosteen shell: HC carbonized at 1500 °C for 2 h delivers the highest reversible capacity of ∼330 mA h g –1 at a current density of 20 mA g –1 , a capacity retention of ∼98% after 100 cycles, and an ICE of ∼83%. Additionally, the sodium-ion storage behavior of HC is deeply analyzed using galvanostatic intermittent titration and cyclic voltammetry technologies.
Theoretical calculations unveil the charge redistribution over abundant interfaces and the enhanced electronic states of Ru/RuS2 heterostructure. The resulting surface electron‐deficient Ru sites display optimized adsorption behavior toward diverse reaction intermediates, thereby reducing the thermodynamic energy barriers. Experimentally, for the first time the laminar Ru/RuS2 heterostructure is rationally engineered by virtue of the synchronous reduction and sulfurization under eutectic salt system. Impressively, it exhibits extremely high catalytic activity for both OER (201 mV @ 10 mA cm−2) and HER (45 mV @ 10 mA cm−2) in acidic media due to favorable kinetics and excellent specific activity, consequently leading to a terrific performance in acidic overall water splitting devices (1.501 V @ 10 mA cm−2). The in‐depth insight into the internal activity origin of interfacial effect could offer precise guidance for the rational establishment of hybrid interfaces.
Prussian blue analogs (PBAs) are especially investigated as superior cathodes for sodium‐ion batteries (SIBs) due to high theoretical capacity (≈170 mA h g−1) with 2‐Na storage and low cost. However, PBAs suffer poor cyclability due to irreversible phase transition in deep charge/discharge states. PBAs also suffer low crystallinity, with considerable [Fe(CN)6] vacancies, and coordinated water in crystal frameworks. Presently, a new chelating agent/surfactant coassisted crystallization method is developed to prepare high‐quality (HQ) ternary‐metal NixCo1−x[Fe(CN)6] PBAs. By introducing inactive metal Ni to suppress capacity fading caused by excessive lattice distortion, these PBAs have tunable limits on depth of charge/discharge. HQ‐NixCo1−x[Fe(CN)6] (x = 0.3) demonstrates the best reversible Na‐storage behavior with a specific capacity of ≈145 mA h g−1 and a remarkably improved cycle performance, with ≈90% capacity retention over 600 cycles at 5 C. Furthermore, a dual‐insertion full cell on the cathode and NaTi2(PO4)3 anode delivers reversible capacity of ≈110 mA h g−1 at a current rate of 1.0 C without capacity fading over 300 cycles, showing promise as a high‐performance SIB for large‐scale energy‐storage systems. The ultrastable cyclability achieved in the lab and explained herein is far beyond that of any previously reported PBA‐based full cells.
Here, a P2-type layered Na Zn TeO (NZTO) is reported with a high Na ion conductivity ≈0.6×10 S cm at room temperature (RT), which is comparable to the currently best Na Zr Si P O NASICON structure. As small amounts of Ga substitutes for Zn , more Na vacancies are introduced in the interlayer gaps, which greatly reduces strong Na -Na coulomb interactions. Ga-substituted NZTO exhibits a superionic conductivity of ≈1.1×10 S cm at RT, and excellent phase and electrochemical stability. All solid-state batteries have been successfully assembled with a capacity of ≈70 mAh g over 10 cycles with a rate of 0.2 C at 80 °C. Na nuclear magnetic resonance (NMR) studies on powder samples show intra-grain (bulk) diffusion coefficients D on the order of 12.35×10 m s at 65 °C that corresponds to a conductivity σ of 8.16×10 S cm , assuming the Nernst-Einstein equation, which thus suggests a new perspective of fast Na ion conductor for advanced sodium ion batteries.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.