3D Porous Amorphous γ-CrOOH on Ni Foam as Bifunctional Electrocatalyst for Overall Water Splitting

Abstract

The development of novel and highly efficient bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an ongoing challenge. The Cr3+ cation has a special electronic configuration (t3 2ge0 g), which facilitates charge transfer and electron capture. However, Cr-based materials applied on water-splitting electrocatalysis is still a research void up to now. Herein, a novel amorphous γ-CrOOH was developed as a bifunctional electrocatalyst toward overall water splitting for the first time. It shows extraordinary HER activity with an ultralow overpotential of only 149 mV at 50 mA cm–2. Meantime, there is a small overpotential of 334 mV at 50 mA cm–2 for the OER. Importantly, the bifunctional electrocatalyst for overall water-splitting electrocatalysis can work with a cell voltage of merely 1.56 V at 10 mA cm–2. Amorphous γ-CrOOH has effectively enhanced the intrinsic electrochemical activity via density functional theoretical calculations. Therefore, this work not only provides a new method for preparation of amorphous γ-CrOOH but also expands the types of catalysts for water splitting.

Engineering Microdomains of Oxides in High‐Entropy Alloy Electrodes toward Efficient Oxygen Evolution

“…Especially, the (CrFeCoNi) 97 O 3 bulk O‐HEA exhibits an outstanding OER catalytic activity which delivers ultralow 196 mV at current density of 10 mA cm −2 in 1 m KOH solution with the Tafel slope of 29 mV dec −1 . The improved catalytic performance can be attributed to the formation of Cr 2 O 3 microdomains (secondary phase) in the solid‐solution matrix, the leaching of Cr ions, [ 18 ] and the structural amorphization at the interface between different phases. This work provides microdomains of oxides strategy for the development of efficient and robust electrocatalyst for large‐scale water splitting.…”

In Situ Construction of a Mn2+-Doped Ni3S2 Electrode with Highly Enhanced Urea Oxidation Reaction Performance

“…The efficient solutions for increasingly serious energy shortage and environmental burden caused by overusing nonrenewable energy are importantly needed. − In the past several years, exploring fungible new type energy support caught the sight of the public, and large amounts of relevant works were carried out. Hydrogen energy combined with the properties of high energy density and free of contamination has been highly praised. − A large number of reports focused on hydrogen generation through water splitting, which was seriously hindered for practical application by its sluggish kinetics of the electrochemical anodic oxygen evolution reaction (OER, 4OH – → 2H 2 O + O 2 + 4e – ) that needs a high thermodynamic potential of 1.23 V to form the O–O bond. − Urea has been regarded as a promising sustainable alternative energy source on account of its high hydrogen content, advantaged properties of high energy density, stability, and abundant reserves. − More importantly, a much lower theoretically potential (0.37 V) than the conventional oxygen evolution reaction (OER) (1.23 V) in water splitting was demanded, which means that the UOR is a desired alternative to OER to realize the effective hydrogen production, relying on the fact that the urea molecule is more prone to be oxidized than the water molecule in alkaline. ,− During the course of urea industrialized synthesis for agriculture fertilizer and feed additive supply, plenty of urea-rich wastewater discharged from factories resulted in huge water contamination problems, which actually could be reused. Decomposition of urea from wastewater with electrochemical methods to produce hydrogen can cover both water contamination and energy issues. , The electrochemical oxidation of urea in alkaline media can be described as shown below …”

Engineering Lithium Ions Embedded in NiFe Layered Double Hydroxide Lattices To Activate Laminated Ni2+ Sites as High‐Efficiency Oxygen Evolution Reaction Catalysts

“…High prices severely restrict commercialization. Nowadays, the development of inexpensive and effective catalysts is still one of the “holy grails.” Among all substitutable non‐noble‐metal catalysts, NiFe layered double hydroxides (LDHs) is considered as a benchmark oxygen evolution electrocatalyst under alkaline conditions . For the basal plane for NiFe LDHs, the edge and corner sites have high activity, but the internal basal plane is inert.…”