Overpotential

About: Overpotential is a research topic. Over the lifetime, 16474 publications have been published within this topic receiving 616632 citations.

Interface engineering of (Ni, Fe)S2@MoS2 heterostructures for synergetic electrochemical water splitting

Abstract: Water splitting to generate hydrogen is a promising and sustainable process, whereas is limited by the large overpotential of electrode materials for cathode hydrogen evolution reaction (HER) and anode oxygen evolution reaction (OER). Here we present an interface engineering strategy to construct efficient bifunctional electrocatalyst based on (Ni, Fe)S2@MoS2 heterostructrues for water-splitting process. The as-prepared (Ni, Fe)S2@MoS2 catalyst gives remarkable electrochemical activity and durability under alkaline environments, with a low overpotential of 130 mV for HER and 270 mV for OER to deliver the current density of 10 mA cm−2, respectively. In combination with in-situ Raman spectra, we demonstrate that the constructed interfacial active sites are favorable to the formation of S-Hads, which synergistically lower the chemisorption energy of the intermediates of HER and OER, thereby facilitating the electrocatalytic overall water splitting. Furthermore, we regulate the interface of (Ni, Fe)S2@MoS2 and electrolyte through changing the composition of electrolyte to achieve much longer electrochemical stability of this hybrid sulfide electrocatalyst.

3D ordered macroporous LaFeO3 as efficient electrocatalyst for Li–O2 batteries with enhanced rate capability and cyclic performance

Abstract: Rechargeable lithium–oxygen (Li–O2) battery is one of the most promising technologies among various electrochemical energy storage systems, while the incapability of the electrocatalyst and the inefficient transport of reactants in the O2 electrode still limit the round-trip efficiency, rate capability, and cycle stability of the Li–O2 battery Here, three-dimensional ordered macroporous LaFeO3 (3DOM-LFO) is synthesized and employed as electrocatalyst in Li–O2 battery with relatively stable TEGDME based electrolyte The Li–O2 cells with 3DOM-LFO show enhanced electrochemical performances, including low overpotential, high specific capacity, good rate capability and cycle stability up to 124 cycles This enhanced catalytic performance might be due to the synergistic effect of the porosity and catalytic activity of the 3DOM-LFO catalyst

Platinum-nickel alloy excavated nano-multipods with hexagonal close-packed structure and superior activity towards hydrogen evolution reaction.

Abstract: Crystal phase regulations may endow materials with enhanced or new functionalities. However, syntheses of noble metal-based allomorphic nanomaterials are extremely difficult, and only a few successful examples have been found. Herein, we report the discovery of hexagonal close-packed Pt–Ni alloy, despite the fact that Pt–Ni alloys are typically crystallized in face-centred cubic structures. The hexagonal close-packed Pt–Ni alloy nano-multipods are synthesized via a facile one-pot solvothermal route, where the branches of nano-multipods take the shape of excavated hexagonal prisms assembled by six nanosheets of 2.5 nm thickness. The hexagonal close-packed Pt–Ni excavated nano-multipods exhibit superior catalytic property towards the hydrogen evolution reaction in alkaline electrolyte. The overpotential is only 65 mV versus reversible hydrogen electrode at a current density of 10 mA cm−2, and the mass current density reaches 3.03 mA μgPt−1 at −70 mV versus reversible hydrogen electrode, which outperforms currently reported catalysts to the best of our knowledge. While crystal phase modification may endow materials with altered functionality, the fabrication of allomorphic noble metal nanomaterials is challenging. Here, the authors synthesize an unusual hexagonal close-packed platinum-nickel alloy and demonstrate its enhanced hydrogen evolution catalytic activity.

Cobalt-Modified Covalent Organic Framework as a Robust Water Oxidation Electrocatalyst

Abstract: The development of stable, efficient oxygen evolution reaction (OER) catalyst capable of oxidizing water is one of the premier challenges in the conversion of solar energy to electrical energy, because of its poor kinetics. Herein, a bipyridine-containing covalent organic framework (TpBpy) is utilized as an OER catalyst by way of engineering active Co(II) ions into its porous framework. The as-obtained Co-TpBpy retains a highly accessible surface area (450 m2/g) with exceptional stability, even after 1000 cycles and 24 h of OER activity in phosphate buffer under neutral pH conditions with an overpotential of 400 mV at a current density of 1 mA/cm2. The unusual catalytic stability of Co-TpBpy arises from the synergetic effect of the inherent porosity and presence of coordinating units in the COF skeleton.

Earth-Abundant Iron Diboride (FeB2) Nanoparticles as Highly Active Bifunctional Electrocatalysts for Overall Water Splitting

Abstract: Developing efficient, durable, and earth-abundant electrocatalysts for both hydrogen and oxygen evolution reactions is important for realizing large-scale water splitting. The authors report that FeB2 nanoparticles, prepared by a facile chemical reduction of Fe2+ using LiBH4 in an organic solvent, are a superb bifunctional electrocatalyst for overall water splitting. The FeB2 electrode delivers a current density of 10 mA cm−2 at overpotentials of 61 mV for hydrogen evolution reaction (HER) and 296 mV for oxygen evolution reaction (OER) in alkaline electrolyte with Tafel slopes of 87.5 and 52.4 mV dec−1, respectively. The electrode can sustain the HER at an overpotential of 100 mV for 24 h and OER for 1000 cyclic voltammetry cycles with negligible degradation. Density function theory calculations demonstrate that the boron-rich surface possesses appropriate binding energy for chemisorption and desorption of hydrogen-containing intermediates, thus favoring the HER process. The excellent OER activity of FeB2 is ascribed to the formation of a FeOOH/FeB2 heterojunction during water oxidation. An alkaline electrolyzer is constructed using two identical FeB2-NF electrodes as both anode and cathode, which can achieve a current density of 10 mA cm−2 at 1.57 V for overall water splitting with a faradaic efficiency of nearly 100%, rivalling the integrated state-of-the-art Pt/C and RuO2/C.