Mori Kohsuke, Itoh Taiki, Kakudo Hiroki, Iwamoto Tomoyuki, Masui Yoichi, Onaka Makoto, Yamashita Hiromi
Graduate School of Engineering, Osaka University, 1-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
Phys Chem Chem Phys. 2015 Oct 7;17(37):24086-91. doi: 10.1039/c5cp04493f. Epub 2015 Aug 28.
A noble-metal-free photocatalytic H2 production system consisting of a Ni-based catalyst, visible-light-responsive organic dye, and graphitic carbon nitride (g-C3N4) as a support has been developed. Characterization by means of XAFS revealed that the deposition of a trinuclear Ni precursor complex, Ni(NiL2)2Cl2 (L = β-mercaptoethylamine), on the g-C3N4 affords a monomeric Ni(ii) species involving β-mercaptoethylamine and aqua ligands in an octahedral coordination geometry. Such a Ni species acts as a hydrogen production site from an aqueous solution without an electron relay reagent by combining with thiazole orange (TO) as a photosensitizer. The emission of the attached TO at around 550 nm decreases with increasing loading amount of Ni catalyst, suggesting electron transfer from TO to the Ni catalyst via the g-C3N4 support. Leaching and agglomeration of the active Ni catalyst and TO are not observed during the photocatalytic reaction. Moreover, the use of highly porous carbon nitride (nanoporous carbon nitride; nanoC3N4) is proven to significantly enhance the photocatalytic activity because of the high surface area due to the unique porous structure as well as high absorption and emission properties of TO associated with nanoC3N4.
一种由镍基催化剂、可见光响应有机染料和作为载体的石墨相氮化碳（g-C3N4）组成的无贵金属光催化制氢系统已被开发出来。通过XAFS进行的表征表明，三核镍前驱体配合物Ni(NiL2)2Cl2（L = β-巯基乙胺）沉积在g-C3N4上可得到一种八面体配位几何结构的、包含β-巯基乙胺和水配体的单核Ni(ii)物种。这种镍物种通过与作为光敏剂的噻唑橙（TO）结合，在没有电子中继试剂的情况下作为从水溶液中制氢的位点。附着的TO在550 nm左右的发射随着镍催化剂负载量的增加而降低，这表明电子通过g-C3N4载体从TO转移到镍催化剂。在光催化反应过程中未观察到活性镍催化剂和TO的浸出和团聚现象。此外，由于独特多孔结构导致的高表面积以及与纳米多孔氮化碳（nanoC3N4）相关的TO的高吸收和发射特性，使用高度多孔的氮化碳（纳米多孔氮化碳；nanoC3N4）被证明能显著提高光催化活性。
