Twofold Effects of Zirconium Doping into TiN on Durability and Oxygen Reduction Reactivity in an Acidic Environment
Twofold Effects of Zirconium Doping into TiN on Durability and Oxygen Reduction Reactivity in an Acidic Environment
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TiN 中锆掺杂对酸性环境下耐久性和氧还原反应性的双重影响
DOI：
10.1021/acs.energyfuels.1c03210
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Daiguji Hirofumi
中科院分区：
文献类型：
--
作者：
Chisaka Mitsuharu;Xiang Rong;Maruyama Shigeo;Daiguji Hirofumi
无碳载体的锡基催化剂最近被开发出来，以避免碳氧化和在酸性聚合物电解液燃料电池阴极中使用稀有的铂族金属。然而，在1.0V以上的高电位下提供足够的耐用性仍然是一个挑战。在此基础上，揭示了在酸性条件下，通过掺杂来提高催化剂对四电子氧还原反应的活性和选择性的新途径。TiN表面被氧化形成金红石型TiO2层，部分锆原子溶解到体相TiN和表面金红石层中。锆原子扭曲了金红石晶格，增加了氧空位的数量，而氧空位对氧化还原至关重要，而其他一些原子偏析形成了单斜相和四方相，从而抑制了TiN微晶的生长。与可逆氢电极在0.1moldm-3H2SO4溶液中相比，优化后的Ti0.8Zr0.2OxNy催化剂在1.0~1.5V的5000次启停循环中表现出优异的耐用性。在5000次循环中，半波电位的下降仅为0.04V，是以前最好的掺磷TiN催化剂的一半。
Carbon-support-free TiN-based catalysts have recently been developed to avoid both carbon oxidation and the use of scarce platinum group metals in acidic polymer electrolyte fuel cell cathodes. However, providing sufficient durability at high potentials above 1.0 V remains a challenge. Herein, zirconium doping is revealed as a new route that enhances catalyst activity and selectivity toward the four-electron oxygen reduction reaction (ORR) in an acidic environment. The TiN surface is oxidized to form rutile TiO2layers, and some zirconium atoms are dissolved into both the bulk TiN and the surface rutile layers. The zirconium atoms distort the rutile lattice to increase the number of oxygen vacancies which are critical for the ORR, whereas some others segregate to form monoclinic and tetragonal ZrO2phases to inhibit the TiN crystallite growth. The optimized Ti0.8Zr0.2OxNycatalysts exhibit excellent durability during 5000 start-up and shut-down cycles between 1.0 and 1.5 V versus the reversible hydrogen electrode in 0.1 mol dm–3H2SO4solution. The decrease in the halfwave potential during the 5000 cycles is only 0.04 V, which is half that of the previous best phosphorus-doped TiN catalyst.