| Hydrogen, the most important energy carrier and chemical raw material, which plays a significant role in different fields like fuel cell, energy storage, chemical and petroleum industry, precious metal smelting, shipbuilding industry, etc. One of the most critical technology to produce high-purity hydrogen is water electrolysis, and alkaline electrolyzer is the most widely used water electrolysis technology due to the advantages of low cost and large scale of hydrogen production, while some shortcomings also exist, such as corrosive electrolyte, low-purity of gas production and low energy efficiency. Recently, solid polymer electrolyte(SPE) electrolyzer that has been developing rapidly, and is considered as the most potential water electrolysis technology with the advantages of compact structure, high current density, high energy efficiency and high pure and high pressure of the gas production. Nowadays,specific catalysts are used to cohere with solid polymer electrolyte(SPE) by spray procedure while preparing the membrane electrode assembly(MEA). Nevertheless, it always comes with the problems like poor stability, short working life and low voltage efficiency attribute to the weak binding interaction between catalysts and SPEAiming at overcoming the technological difficulties of SPE electrolyzer, this work provided and adopted a novel method to prepare high-performance MEAs applied in SPE electrolyzer through ion exchanging-reduction deposition. We investigated the influence of various precursors, metal loadings, structure of catalysts layer and reductant on the performance of MEAs used in water electrolysis, and the MEAs were also characterized by XRD, ICP-AES and SEM.Results indicate that catalyst prepared by the above method can spread on proton exchange membrane(PEM) uniformly with a thickness of 1-2 μm and strong adhesion with SPE. We found that introduction of iridium made anode catalyst layer(ACL) tends to form a cotton-like 3D structure. Under optimized experimental conditions, MEA prepared has dual-metal anode catalyst layer with 1.4 mg/cm2 of Pt and 0.4 mg/cm2 of Ir, and the cathode catalyst layer contains 1.0 mg/cm2 of Pt and it exhibits a current denstiy of 505 mA/cm2 for water splitting(voltage efficiency: 84% vs. HHV) under 75 ℃ and 1 atm, while MEA with pure Pt metal ACL with the same current density at 2.47 V(voltage efficiency: 60% vs. HHV) Furhtermore, the cell voltage hardly changed after 5 h water electrolysis test,demonstrating the MEA with dual-metal ACL had excellent stability.We also studied water electrolysis performance and electrode stability of SPE electrolyzer composited of 8 pieces of MEAs(total catalyst layer area is 270 cm2) and the results show that under 75 ℃, 1atm and 500 mA/cm2, SPE electrolyzer operated at 13.71 V and each MEA has the average cell voltage of 1.71 V, representing almost the best level of water electrolysis performance around the world. After 8 h water electrolysis test, cell voltage of electrolyzer raised slightly to 14.16 V, which are believed to be coming from electrolyzer components instead of MEAs themselves.Conclusively, this work has successfully prepared MEAs with high-performance through ion exchanging-reduction deposition, and the novel MEAs have the critical merits of strong adhersion with SPE, high voltage efficiency, good stability and great potential of practical application for water electrolysis. |
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