Abstract
Electrochemical water splitting is one of the most sustainable approaches for generating hydrogen. Because of the inherent constraints associated with the architecture and materials, the conventional alkaline water electrolyzer and the emerging proton exchange membrane electrolyzer are suffering from low efficiency and high materials/operation costs, respectively. Herein, we design a membrane-free flow electrolyzer, featuring a sandwich-like architecture and a cyclic operation mode, for decoupled overall water splitting. Comprised of two physically-separated compartments with flowing H2-rich catholyte and O2-rich anolyte, the cell delivers H2 with a purity >99.1%. Its low internal ohmic resistance, highly active yet affordable bifunctional catalysts and efficient mass transport enable the water splitting at current density of 750 mA cm−2 biased at 2.1 V. The eletrolyzer works equally well both in deionized water and in regular tap water. This work demonstrates the opportunity of combining the advantages of different electrolyzer concepts for water splitting via cell architecture and materials design, opening pathways for sustainable hydrogen generation.
Highlights
Electrochemical water splitting is one of the most sustainable approaches for generating hydrogen
The conventional alkaline water electrolyzer dates back in 17898,9. It enables the use of cost-effective catalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), enjoying low capital expenditure and operating expenses[10]
The cell comprises two physically separated compartments, connected by wires that allows the transfer of electrons, for oxygen evolution and hydrogen evolution reactions, respectively
Summary
Electrochemical water splitting is one of the most sustainable approaches for generating hydrogen. We design a membrane-free flow electrolyzer, featuring a sandwich-like architecture and a cyclic operation mode, for decoupled overall water splitting. This work demonstrates the opportunity of combining the advantages of different electrolyzer concepts for water splitting via cell architecture and materials design, opening pathways for sustainable hydrogen generation. Compared with the electrolyzers containing solid membranes, this membrane-free cell is less complex, potentially more robust in the harsh reaction environments, and cheaper It can operate using different aqueous electrolyte[27]. The divergent electrode-flow-through (DEFT) membraneless alkaline electrolysis takes advantage of the divergent flow of electrolyte to maintain gas separation while delivering excellent performance in a pilot plant[35,36] Notwithstanding these advantages, many membrane-free cells suffer from large ohmic drops. The bifunctional catalysts are based on affordable Fe/Co compounds, which opens opportunities for real-life applications
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