Enhanced photoredox water splitting of Sb–N donor–acceptor pairs in TiO2

Abstract

The development of noble-metal-free TiO₂-based catalysts is of significant interest for photoredox H₂ production. In this study, we proposed an efficient Sb–N donor–acceptor pair doping strategy to enhance the H₂ production of anatase TiO₂. The as-obtained Sb and N-co-doped TiO₂ showed the high solar-light water splitting rate of ca. 2330 μmol h⁻¹ g⁻¹. In contrast, the photocatalytic hydrogen generation of the single N or Sb-doped TiO₂ was significantly lower (ca. 191.7 or 470 μmol h⁻¹ g⁻¹), respectively, directly proving the enhanced synergistic effect of Sb and N in anatase TiO₂. During the hydrothermal treatment of massive TiO₂, Sb could substitute the Ti atoms in anatase TiO₂. Similarly, the N atoms can be occupied by O. The co-doped Sb/N atoms acted as a donor–acceptor pair and regulated the band gap of anatase TiO₂ from 3.11 to 2.98 eV, significantly limiting the recombination rate of charge carriers. Furthermore, the photoelectric features of this catalytic system were thoroughly investigated via various characterization methods (e.g., UV-vis spectroscopy, EPR, PL, EIS) to clarify the excellent photoredox water-splitting enhancement of the Sb–N donor–acceptor pairs in anatase TiO₂. Moreover, in addition to Sb, Cr and Mo can construct donor–acceptor pairs with N in TiO₂; this implies the extensive applicability of the donor–acceptor pair doping strategy in TiO₂-based photoredox water splitting.