Self-activated Rh-Zr mixed oxide as a nonhazardous cocatalyst for photocatalytic hydrogen evolution

• Published in: Chemical science (Cambridge) 2020-07, Vol.11 (26), p.6862-6867
• Main Authors: Nishino, Toshio, Saruyama, Masaki, Li, Zhanzhao, Nagatsuma, Yoshie, Nakabayashi, Mamiko, Shibata, Naoya, Yamada, Taro, Takahata, Ryo, Yamazoe, Seiji, Hisatomi, Takashi, Domen, Kazunari, Teranishi, Toshiharu
• Format: Article
• Language: English
• Subjects: Catalytic activity; Chemical evolution; Chemistry; Cobalt oxides; Hydrogen; Hydrogen evolution; Hydrogen production; Photocatalysis; Photoelectrons; Strontium titanates; Water splitting; Zirconium oxides
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d0sc01363c

Efficient, robust and environmentally friendly cocatalysts for photocatalysts are important for large-scale solar hydrogen production. Herein, we demonstrate that a Rh-Zr mixed oxide is an efficient cocatalyst for hydrogen evolution. Impregnation of Zr and Rh precursors (Zr/Rh = 5 wt/wt%) formed RhZrO x cocatalyst particles on Al-doped SrTiO 3 , which exhibited 31× higher photocatalytic water-splitting activity than a RhO x cocatalyst. X-ray photoelectron spectroscopy proved that the dissociation of Cl − ions from preformed Rh-Cl-Zr-O solid led to formation of the active phase of RhZrO x , in which the Zr/Rh ratio was critical to high catalytic activity. Additional CoO x loading as an oxygen evolution cocatalyst further improved the activity by 120%, resulting in an apparent quantum yield of 33 (±4)% at 365 nm and a long durability of 60 h. Our discovery could help scale up photocatalytic hydrogen production. An efficient, robust and environmentally friendly Rh-Zr mixed oxide formed though the activation of Rh-Cl-Zr-O solid efficiently functions as a HER cocatalyst on Al-doped SrTiO 3 .