CoFeCr LDH Catalyst for Water Splitting OER
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Solution Overview
Problem
Current water-splitting technologies face limitations due to the sluggish kinetics of the oxygen evolution reaction (OER) and the high cost of noble-metal-based catalysts, with Earth-abundant metal-based catalysts like Ni—Fe LDHs having complex structures that hinder further development.
Innovation Solution
A ternary composite material comprising cobalt, iron, and chromium interspersed with a hydroxide layer is developed, which demonstrates superior OER catalytic performance with low overpotentials, with chromium acting as an oxidation scavenger to retain cobalt in a catalytically active form.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If noble-metal-based catalysts (IrO2, RuO2) are used for OER, then catalytic efficiency is improved, but cost increases significantly
Solution Approach 1:
The patent replaces expensive noble metals (Ir, Ru) with earth-abundant transition metals (Co, Fe, Cr) to create a cost-effective catalyst. The LDH structure provides stability while the Earth-abundant metals reduce material cost significantly, making the catalyst economically viable for industrial water splitting applications.
Solution Approach 2:
The patent creates a composite LDH material containing multiple metal species (Co, Fe, Cr) with different functions. Co provides catalytic activity, Fe enhances stability, and Cr suppresses oxidation. This composite approach synergistically combines the benefits of different metals to achieve high efficiency without noble metals.
2Quantity of substance
If Earth-abundant metal-based catalysts (Ni-Fe LDH) are used, then cost is reduced, but structural complexity increases making development difficult
Solution Approach 1:
The patent extracts Ni from the conventional Ni-Fe LDH structure and replaces it with Co, while adding Cr as a third component. This simplifies the structural analysis compared to Ni-Fe LDH while maintaining Earth-abundant metal composition, making the catalyst easier to study and develop further.
Solution Approach 2:
The patent assigns specific local functions to each metal component: Co species at catalytic sites provide OER activity, Fe species enhance overall stability, and Cr species locally suppress oxidation. This functional differentiation within the composite structure optimizes performance while maintaining simplicity in overall design.
3Productivity
If CoFe composite is used, then OER activity is achieved, but oxidation of cobalt reduces catalytic performance
Solution Approach 1:
The patent introduces Cr species as an intermediary that mediates between Co and the oxidizing environment. Cr acts as a protective layer or buffer that suppresses direct oxidation of Co species, thereby maintaining Co in its catalytically active state while still allowing OER to proceed efficiently.
Solution Approach 2:
The patent converts the harmful oxidation effect into a beneficial protective mechanism. By allowing controlled oxidation of Cr species instead of Co, the system uses the oxidation tendency to protect the catalytically active Co species, transforming a potential harm (oxidation) into a benefit (protection of active sites).
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The CoFeCr composite material achieves improved OER catalytic activity compared to CoFe composites, requiring lower overpotentials and showing enhanced stability and durability, comparable to or exceeding that of commercial Ir-based catalysts.
Implementation Method 1
a ternary composite material comprising cobalt, iron and chromium interspersed with a hydroxide layer that is able to catalyse OER with low overpotentials (η)
Implementation Method 2
Oxygen may be generated at the anode via the oxygen evolution reaction (OER). OER involves a four-electron-transfer process
Implementation Method 3
chromium acting as an oxidation scavenger to retain cobalt in a catalytically active form
Implementation Method 4
Water-splitting may be carried out in an electrolyser generating hydrogen at the cathode via the hydrogen evolution reaction (HER). Oxygen may be generated at the anode via the oxygen evolution reaction (OER)
Implementation Method 5
contacting a conductive substrate with a solution comprising cobalt, iron and chromium ions, and applying a voltage across the substrate and a counter electrode through the solution to electrodeposit a composite material comprising cobalt, iron and chromium species on the substrate
Data Source
AI summary
The invention relates to a layered double hydroxide (LDH) material and methods for using the LDH material to catalyse the oxygen evolution reaction (OER) in a water-splitting process. The invention also provides a composition, a catalytic material, an electrode and an electrolyser including the LDH material. In particular, the LDH material includes a metal composite including cobalt, iron, chromium and optionally nickel species interspersed with a hydroxide layer.