Development of Ta 3 N 5 photocatalysts with nanoplate structure and high efficiency for H 2 generation Junie Jhon M. Vequizo 1, *, Swapnil Karade 1 , Takashi Hisatomi 1 , Jiadong Xiao 2 , Daling Lu 1 , Tsuyoshi Takata 2 , Akira Yamakata 3 and Kazunari Domen 1, 4, ‡ 1 Institute of Aqua Regeneration, Shinshu University, 4-17-1 Wakasato, Nagano-shi, Nagano, Japan, 2 Research Initiative for Supra-Materials, Shinshu University, 4-17-1 Wakasato, Nagano- shi, Nagano, Japan, 3 Faculty of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama, Japan, 4 Office of University Professors, The University of Solar-driven photocatalytic water splitting provides a feasible way to produce hydrogen fuel in a facile way. Ta 3 N 5 gains attention as a candidate photocatalytic material due to its band structure suitable for water splitting under visible light. To date, Ta 3 N 5 demonstrated high quantum efficiency (~9.4% at 420 nm) for water oxidation in the presence of AgNO 3 , 1 while lower yield for water reduction, which limits its effective utilization for overall water splitting. Notably, introducing various aliovalent metal ions such as Mg 2+ and Zr 4+ can significantly enhance the performance in water splitting of Ta 3 N 5 . 2-3 So far, Ta 3 N 5 synthesized from Ta nanoparticles with incorporated Zr and Mg dopants exhibited improvement on the H 2 generation after Pt modification in aqueous methanol solution. 2 These dopants enhance the bulk properties, tune the surface defects, and also provide efficient transfer of electrons from Ta 3 N 5 to Pt nanoparticles. In this work, we synthesized Ta 3 N 5 in a different way by selecting a laboratory-made TaS 2 as a Ta precursor. TaS 2 has demonstrated its strong potential to manufacture metal oxynitrides, 4 with enhanced water splitting performance. For the synthesis of Zr-doped Ta 3 N 5 , TaS 2 , NaCl, and ZrOCl 2 were blended together. Nitridation of the mixture at 900 o C for 2 h produced mainly Ta 3 N 5 at low Zr dopant concentration (<10 mol%), and a minor ZrO 2 impurity appeared at Zr ≥ 10 mol%. Loading of Pt and CrO x cocatalysts was carried out via sequential photodeposition. As depicted in Fig.1, Zr doping significantly enhanced the H 2 generation rate of Ta 3 N 5 and the optimum amount of Zr was 20 mol% with H 2 generation rate of ~ 370 μmol/h in the presence of ascorbic acid as hole scavenging reactants. Sequential loading of Rh-CrO x nanoparticles is as effective as Pt-CrO x . Detailed findings will be discussed during the conference. Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, Japan *Presenting author: jjmvequizo@shinshu-u.ac.jp ‡ Corresponding author: domen@chemsys.t.u-tokyo.ac.jp
References 1. Wang et al., Nano Research ,16, 4562 (2023). Xiao et al., J. Am. Chem. Soc. 143, 10059 (2021). Xiao et al., Nat. Catal . 3, 932 (2020). Xiao et al., Nat. Commun. 14,8030(2023)
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