Porous Cu/Cu2O Xerogel Catalyst for CO2-to-Ethanol Conversion
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Solution Overview
Problem
Existing copper-based catalysts for electrocatalytic CO2 conversion to C2+ chemicals face limitations in Faradaic efficiency (FE) and partial current density due to high-energy barriers and competitive hydrogen evolution reactions, with reported catalysts achieving FE below 35% and J below 20 mA/cm2, which are insufficient for commercial usage.
Innovation Solution
A copper/copper oxide (Cu/Cu2O) xerogel catalyst is synthesized through wet-chemistry, featuring a porous structure with high surface area and dense Cu0—Cu+ interfaces, enhancing CO2 activation and C—C dimerization by confining reaction intermediates in proximity to active sites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If flat copper surface is used for electrocatalytic CO2 conversion, then the catalyst structure is simple, but the Faradaic efficiency for C2 product is limited to about 20% due to high-energy barrier and competitive hydrogen evolution reaction
Solution Approach 1:
The patent employs a porous copper foam substrate as the catalyst support, which provides high surface area and three-dimensional reaction sites. The porous structure increases the number of active sites available for CO2 reduction while maintaining structural simplicity, thereby improving Faradaic efficiency for C2 products without significantly increasing device complexity.
Solution Approach 2:
The patent uses a composite copper-copper oxide catalyst system where metallic copper and copper oxide coexist on the porous foam substrate. This composite structure leverages the synergistic effects between Cu0 and Cu2O phases, where Cu2O facilitates CO binding and C-C coupling while Cu0 provides conductive pathways, resolving the contradiction between structural simplicity and catalytic efficiency.
2Reliability
If nano-structuring of copper-based alloy is used to improve reaction intermediate binding energy, then the Faradaic efficiency improves, but the partial current density remains too small for commercial usage due to low surface area
Solution Approach 1:
The porous copper foam substrate provides inherently high surface area compared to flat or densely packed nanostructures. The three-dimensional porous network allows numerous reaction sites to be accessible simultaneously, enabling both high Faradaic efficiency through optimized binding energy and high partial current density through increased active site availability.
Solution Approach 2:
The patent transitions from two-dimensional flat surfaces or zero-dimensional nanoparticles to a three-dimensional porous foam structure. This dimensional change dramatically increases the accessible surface area while maintaining open pathways for mass transport, thereby achieving both high selectivity (Faradaic efficiency) and high productivity (partial current density).
3Reliability
If oxide-derived Cu is used to promote CO binding and C-C coupling, then the selectivity for C2 production improves with FEC2H4 up to about 60%, but the partial current density is still too small
Solution Approach 1:
The porous copper foam substrate provides high surface area that compensates for the inherently lower current density of oxide-derived copper. The three-dimensional porous structure allows numerous Cu2O sites to participate in CO binding and C-C coupling simultaneously, maintaining high selectivity while increasing overall productivity through parallel reaction pathways.
Solution Approach 2:
The patent optimizes the copper oxide content and composition on the porous substrate to achieve the right balance between CO binding affinity and electron transfer efficiency. By controlling the Cu2O/Cu0 ratio and distribution within the porous structure, the catalyst achieves both high C2 selectivity and improved partial current density compared to conventional oxide-derived copper.
4Reliability
If residual oxygen or Cu+ atoms and under-coordinated surface Cu atoms are used to improve C2 selectivity, then the Faradaic efficiency increases, but the partial current density remains below 20 mA/cm2
Solution Approach 1:
The porous foam structure provides high surface area with exposed under-coordinated Cu atoms at pore edges and surfaces. These under-coordinated sites exhibit enhanced catalytic activity for C2 production, and the porous architecture allows numerous such sites to function simultaneously, achieving both high selectivity and improved current density through increased site availability.
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 Cu/Cu2O xerogel achieves up to 40% Faradaic efficiency for ethanol production and 31.2 mA/cm2 partial current density, significantly surpassing previous catalysts, with further enhancements to 72.1 mA/cm2 in a flow cell reactor, demonstrating high selectivity and productivity for C2+ chemicals.
Implementation Method 1
adding a reducing agent to the water solution, and separating a product powder from the water solution, wherein the product powder is a copper/copper oxide xerogel
Implementation Method 2
enhancing CO2 activation and C—C dimerization by confining reaction intermediates in proximity to active sites
Implementation Method 3
The electrosynthesis of liquid fuels from CO2 is a promising technology for performing this function
Data Source
AI summary
An electrocatalytic catalyst is provided. The electrocatalytic catalyst includes a xerogel including copper (I) oxide and copper.