Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Chemistry. 2013 Jun 3;19(23):7480-6. doi: 10.1002/chem.201300579. Epub 2013 Apr 12.
Tantalum nitride (Ta3N5) modified with various O2-evolution cocatalysts was employed as a photocatalyst for water oxidation under visible light (λ>420 nm) in an attempt to construct a redox-mediator-free Z-scheme water-splitting system. Ta3N5 was prepared by nitriding Ta2O5 powder under a flow of NH3 at 1023-1223 K. The activity of Ta3N5 for water oxidation from an aqueous AgNO3 solution as an electron acceptor without cocatalyst was dependent on the generation of a well-crystallized Ta3N5 phase with a low density of anionic defects. Modification of Ta3N5 with nanoparticulate metal oxides as cocatalysts for O2 evolution improved water-oxidation activity. Of the cocatalysts examined, cobalt oxide (CoO(x)) was found to be the most effective, improving the water-oxidation efficiency of Ta3N5 by six to seven times. Further modification of CoO(x)/Ta3N5 with metallic Ir as an electron sink allowed one to achieve Z-scheme water splitting under simulated sunlight through interparticle electron transfer without the need for a shuttle redox mediator in combination with Ru-loaded SrTiO3 doped with Rh as a H2-evolution photocatalyst.
氮化钽 (Ta3N5) 经各种 O2 析出助催化剂改性后，作为光催化剂用于可见光（λ>420nm）下水氧化，旨在构建无需氧化还原介体的 Z 型水分解体系。Ta3N5 通过 Ta2O5 粉末在 NH3 气流中于 1023-1223K 下氮化制备。Ta3N5 在没有助催化剂的情况下从水合硝酸银溶液中作为电子受体氧化水的活性取决于具有低阴离子缺陷密度的结晶良好 Ta3N5 相的生成。用纳米颗粒金属氧化物作为 O2 析出助催化剂改性 Ta3N5 可提高水氧化活性。在研究的助催化剂中，氧化钴 (CoO(x)) 被发现是最有效的，将 Ta3N5 的水氧化效率提高了六到七倍。进一步用金属铱修饰 CoO(x)/Ta3N5 作为电子汇，允许在无需穿梭氧化还原介体的情况下，结合负载 Ru 的 SrTiO3 掺杂 Rh 作为 H2 析出光催化剂，通过粒子间电子转移实现模拟太阳光下的 Z 型水分解。
