Designing Binary Ru–Sn Oxides with Optimized Performances for the Air Electrode of Rechargeable Zinc–Air Batteries

Abstract

Because of the sluggish kinetics of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), binary ruthenium-tin oxides synthesized by a hydrothermal method with postannealing at 450 °C for 2 h are first proposed as bifunctional catalysts for these two reactions on the air electrode of rechargeable zinc-air batteries. The binary Ru-Sn oxides in various compositions show the typical oxide solid solution in the rutile phase. Among all binary Ru-Sn oxides, RuSn73 (70 atom % RuO and 30 atom % SnO) and RuSn37 (30 atom % RuO and 70 atom % SnO) show the highest catalytic activities toward the OER and ORR, respectively. Consequently, a novel design of the air electrode consisting of a RuSn37 coating on the carbon paper and a Ti mesh coated with RuSn73 (denoted RuSn(37-C|73-Ti)) is proposed to possess the optimal charge-discharge performances. A unique cell employing such an air electrode has been demonstrated to exhibit a very low charge-discharge cell voltage gap of 0.75 V at 10 mA cm. This cell with a peak power density of 120 mW cm at the current density of 235 mA cm also shows an outstanding charge-discharge stability over 80 h. This cell also exhibits an exceptionally high charge rate capability at 150 mA cm with a low charging voltage of 2.0 V.

The Influence of RuO2Distribution and Dispersion on the Reactivity of RuO2−SnO2Composite Oxide Catalysts Probed by CO Oxidation

“…Figure (a) demonstrates that on the diffraction patterns of 2 % SnRuO‐IMP and 2 %SnRuO‐DP, a novel second phase is observed at 2θ=28.12° and 35.08° in addition to the SnO 2 phase, which can be attributed to the diffraction of (110) and (101) of RuO 2 crystalline phase on the catalyst surface. In contrast, for 2 %SnRuO‐CP samples, no RuO 2 crystalline phase can be observed, which implies that Ru 4+ cations could have entered into the rutile SnO 2 lattice matrix to form a solid solution structure ,. However, for the samples containing 5 % Ru loadings, the diffraction feature of RuO 2 crystalline phase is observed for all the catalysts.…”

“…Although individual RuO 2 or SnO 2 , are found to show activity for CO oxidation, RuO 2 −SnO 2 composite oxides have been rarely studied as catalysts for those air pollution control reactions up to now. People have shown main interest on using RuO 2 −SnO 2 as electrochemical materials, such as electrode, super‐capacitors and electrocatalysts . It has been reported that change of preparation methods can significant affect the structure and performance of RuO 2 −SnO 2 composite oxides.…”

“…It has been reported that change of preparation methods can significant affect the structure and performance of RuO 2 −SnO 2 composite oxides. By using a hydrothermal procedure and high‐energy mechanical alloying of pure SnO 2 and RuO 2 powders, rutile Sn−Ru−O solid solutions can be formed. Hu et al.…”

“…RuO 2 À SnO 2 composite oxides have been widely investigated as dimensionally stable anodes in chloro-alkali industry and oxygen evolution catalysts in water electrolysis [1][2][3][4][5][6][7] due to their excellent electrochemical properties. In addition, RuO 2 /SnO 2 also displays high reactivity and stability for HCl oxidation to produce Cl 2 , which is known as Deacon reaction.…”

“…People have shown main interest on using RuO 2 À SnO 2 as electrochemical materials, such as electrode, super-capacitors and electrocatalysts. [4][5][6] It has been reported that change of preparation methods can significant affect the structure and performance of RuO 2 À SnO 2 composite oxides. By using a hydrothermal procedure [4][5][6] and high-energy mechanical alloying of pure SnO 2 and RuO 2 powders, [5] rutile SnÀ RuÀ O solid solutions can be formed.…”