Pyrochlore Electrolyte Catalyst for Acidic OER
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Solution Overview
Problem
Current electrocatalysts for oxygen evolution reaction (OER) in acidic media are sluggish and lack stability, hindering the production of hydrogen fuel from water, with existing catalysts like RuO2 losing activity due to oxidation and IrO2 having lower activity and stability issues.
Innovation Solution
Development of a porous metal oxide electrocatalyst with a pyrochlore phase structure (A2B2On) comprising interconnected primary particles, fabricated using a sol-gel method, which exhibits high stability and activity in acidic conditions, outperforming existing catalysts in terms of mass current density and cycle durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RuO2 catalyst is used for OER in acidic media, then high OER activity is achieved, but the catalyst is oxidized to RuO4 and loses electrocatalytic activity during use
Solution Approach 1:
The patent uses composite perovskite structures (e.g., CaMnO3, LaMnO3) that combine multiple metal elements to create a material that exhibits both high OER activity and exceptional stability in acidic media. The composite structure prevents the oxidation and dissolution problems seen in single-element RuO2 catalysts while maintaining catalytic performance.
Solution Approach 2:
The patent modifies the chemical composition parameters of the catalyst by using perovskite structures with specific A-site and B-site metal combinations. This parameter change transforms the catalyst's properties to achieve stability in acidic conditions while preserving high OER activity, overcoming the limitations of traditional RuO2.
2Reliability
If IrO2 catalyst is used for OER in acidic media, then high corrosion resistance and stability are achieved, but OER activity is much lower than RuO2
Solution Approach 1:
The patent employs perovskite composite materials that combine the stability characteristics of IrO2 with the high activity characteristics of RuO2 and other active catalysts. The multi-element perovskite structure achieves a synergistic effect where the material is both highly stable and highly active for OER.
Solution Approach 2:
The patent creates catalysts with different local compositions at A-sites and B-sites within the perovskite structure. By optimizing the local chemical environment at each site, the catalyst achieves both high surface activity for OER and bulk stability in acidic media, resolving the activity-stability trade-off.
3Ease of manufacture
If perovskite structures are used as electrocatalysts, then reduced cost and structural flexibility are achieved, but stability in acidic media is insufficient
Solution Approach 1:
The patent uses perovskite composite structures with specific metal combinations (e.g., CaMnO3, LaMnO3, SrFeO3) that provide both cost-effectiveness by replacing noble metals and exceptional stability in acidic media through the robust perovskite crystal structure. The composite nature allows tuning of both cost and stability properties.
Solution Approach 2:
The perovskite structure serves multiple functions: it provides structural flexibility for compositional tuning, ensures cost reduction by using abundant metals, and delivers acid stability through its robust crystal structure. This multi-functionality resolves the contradiction between ease of manufacture and reliability.
4Productivity
If OER catalysts are designed for alkaline media, then good performance is achieved, but the reaction process becomes sluggish in acidic media
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst to create perovskite structures specifically optimized for acidic media. By adjusting the A-site and B-site metal compositions, the catalyst achieves high OER performance in acidic conditions, making it adaptable to the required media environment while maintaining excellent activity.
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 pyrochlore-based electrocatalyst achieves exceptional stability and high OER activity in acidic media, maintaining performance over 1000 potential cycles without degradation, surpassing the stability and activity of previous catalysts, with a mass current density of up to 88.8 A/g at 0.22 V in 0.1 M HClO4.
Implementation Method 1
The electrocatalyst comprises a porous metal oxide structure having particulate walls separating a plurality of pores, where each particulate wall comprises interconnected primary particles. The porous metal oxide structure comprises a pyrochlore phase of chemical formula A2B2On
Implementation Method 2
A method of forming an electrocatalyst comprises: heating a mixture including: (a) at least one first metal salt for forming one or more A-site metals, (b) at least one second metal salt for forming one or more B-site metals, (c) a chelating agent, and (d) a porogen; curing the mixture to form a gel
Implementation Method 3
heating the gel to form a porous metal oxide structure comprising a pyrochlore phase of chemical formula A2B2On
Implementation Method 4
heating the gel to form a porous metal oxide structure comprising a pyrochlore phase
Data Source
AI summary
An oxygen evolution reaction (OER) electrocatalyst for acidic media comprises a metal oxide structure comprising a pyrochlore phase of chemical formula A.sub.2B.sub.2O.sub.n, wherein A comprises one or more A-site metals, B comprises one or more B-site metals, and 6.0.ltoreq.n.ltoreq.7.3. The metal oxide structure exhibits a mass current density of at least about 20 A/g at an over-potential of 0.22 V in 0.1 M HClO.sub.4. According to another embodiment, an electrocatalyst for acidic media comprises a porous metal oxide structure having particulate walls separating a plurality of pores, where each particulate wall comprises interconnected primary particles. The porous metal oxide structure comprises a pyrochlore phase of chemical formula A.sub.2B.sub.2O.sub.n, wherein A comprises one or more A-site metals, B comprises one or more B-site metals, and 6.0.ltoreq.n.ltoreq.7.3.