Iridium Improves BOR Selectivity of Ru-Based Catalysts for Direct Borohydride Fuel Cells

ACS Applied Engineering Materials Pub Date : 2025-01-23 DOI:10.1021/acsaenm.4c0076310.1021/acsaenm.4c00763

Lin Kang, Yexuan Zhang, Cheng Liu, Jinyu Ye, Liangyao Xue, Jiaqi Zhang, Lirong Zheng, Youyong Li, Wen Guo and Bo Zhang*,

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Abstract

Direct borohydride fuel cells (DBFCs) are considered as a promising energy storage method because of their high theoretical cell voltage and high energy density. However, the sluggish kinetics and low fuel utilization have limited its practical application. According to density functional theory calculations, we found that the high-valency ruthenium (Ru) site not only promotes electrochemical borohydride oxidation reaction (eBOR) kinetics but also tends to catalyze hydrolysis. Doping iridium (Ir) species into a Ru-based catalyst effectively inhibits hydrolysis and improves eBOR selectivity. Herein, a catalyst of Ru-Ir supported on carbon powder (RuIrO_x-C) was prepared by a sol–gel method. The RuIrO_x-C catalyst achieves a remarkable power density of 236 mW cm^–2, which is 47% higher than that of the control RuO_x-C catalyst. Additionally, DBFCs show excellent stability and can work continuously for 210 h at a current density of 100 mA cm^–2. In situ attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIRS) indicated that the high-valence Ru site accelerates the eBOR kinetics, while reducing the adsorption of water molecules on the catalyst surface. This reduction inhibits the hydrolysis reaction and improves the reaction selectivity. This work opens a way for the design and development of eBOR catalysts with excellent activity, stability, and selectivity.

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ACS Applied Engineering Materials 材料科学-

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期刊介绍： ACS Applied Engineering Materials is an international and interdisciplinary forum devoted to original research covering all aspects of engineered materials complementing the ACS Applied Materials portfolio. Papers that describe theory simulation modeling or machine learning assisted design of materials and that provide new insights into engineering applications are welcomed. The journal also considers experimental research that includes novel methods of preparing characterizing and evaluating new materials designed for timely applications. With its focus on innovative applications ACS Applied Engineering Materials also complements and expands the scope of existing ACS publications that focus on materials science discovery including Biomacromolecules Chemistry of Materials Crystal Growth & Design Industrial & Engineering Chemistry Research Inorganic Chemistry Langmuir and Macromolecules.The scope of ACS Applied Engineering Materials includes high quality research of an applied nature that integrates knowledge in materials science engineering physics mechanics and chemistry.