Optimizing energy consumption considering interfacial pH changes using an asymmetric electrode design: The case of alkaline electrolysis

Author(s)

Wosiak, Gabriel ; Staciaki, Felipe ; Von Stein, Raphaella ; Pereira, Ernesto

• Document type: Journal article
• Source: INTERNATIONAL JOURNAL OF HYDROGEN ENERGY; v. 106, p. 8-pg., 2025-03-06.

Abstract

Electrochemical reactions conducted in aqueous electrolytes are normally accompanied by consumption or production of H+/OH- ions, which can lead to significant interfacial pH (pHi) changes near the electrode surface. In electrochemistry the pHi change occurs in various processes and plays a role impact in reactions increasing the energy consumption and, consequently, negatively affecting the process efficiency. In this paper, we present a simple and scalable method to mitigate the pHi changes by using a cell design with electrode asymmetry increasing the anode area relative to the cathode area, thereby reducing energy consumption. This configuration has been tested in alkaline wa-ter electrolysis using a multivariate approach in both laboratory and industrial current density conditions, and the results were supported by numerical simulations. The results indicated that an increase in the ratio between electrode areas reduces the cell potential and energy consumption, improving the energy efficiency (11.6%). The simulations demonstrated that when the area quotient (AQ) is 30, the interfacial pH changes is 397.4 times slower compared to an AQ = 1. Finally, under high current conditions, the asym-metric electrode configuration significantly reduces the cell potential leading to 17.1% of saved energy at jcat = 200 mA cm- 2. These results indicate that the method can be scaled and applied in various settings, offering a promising solution to the challenge of mitigating the interfacial pH changes and improving energy efficiency and performance in electrochemical processes, especially industrial applications. (AU)

• FAPESP's process: 21/11630-1 - Development of new materials and methods for capacitive deionization
• Grantee: Felipe Staciaki da Luz
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 17/11986-5 - Generation and storage of New Energy: bringing technological development for the country
• Grantee: Ana Flávia Nogueira
• Support Opportunities: Research Grants - Research Centers in Engineering Program
• FAPESP's process: 18/24383-0 - Coupled electrochemical and microwave synthesis of new optimized electrode materials
• Grantee: Gabriel Wosiak Leite
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 13/07296-2 - CDMF - Center for the Development of Functional Materials
• Grantee: Elson Longo da Silva
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 22/05254-0 - Carbon dioxide electrochemical reduction to polymeric precursors
• Grantee: Eryka Thamyris Damascena Nobrega Cavalcanti
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 14/50249-8 - Green chemistry: sustainable synthetic methods employing benign solvents, safer reagents, and bio-renewable feedstock
• Grantee: Arlene Gonçalves Corrêa
• Support Opportunities: Research Grants - Research Centers in Engineering Program