Spatially Controlled Photogenerated Charge Carriers Induced by SrTiO₃-Architectured Heterojunction Nanocubes for a Photocatalytic Hydrogen Evolution Reaction

Effective charge separation and transfer of photoinduced electron (e–)–hole (h+) pairs in a perovskite photocatalyst, namely, SrTiO3 (STO), are crucial factors for a highly effective and durable photocatalytic hydrogen evolution reaction (HER). Herein, we develop a highly efficient pathway based on a semiconductor–metal heterostructured photocatalyst, in which Ir-doped (STO) nanocubes loaded with Ag nanoparticles are prepared by two facile approaches for water splitting driven by visible-light irradiation. This strategy was easily accessible to highly enhanced photocatalytic HER activities by (i) Ir3+ doping in the forbidden gap of STO nanocubes for broadening the light absorption wavelengths up to 730 nm and (ii) incorporating Ag nanoparticles for controlling the electron–hole transportation at the interface and developing active reaction sites. Remarkably, the as-synthesized Ag/Ir/STO showed apparent quantum efficiencies of up to 0.17% and 0.06% under UV light and 420 nm illumination, respectively, which are 7.4-, 2-, and 1.6-fold higher than those of bare STO, binary Ag/STO, and Ir/STO, respectively. It also possessed outstanding stability in the photocatalytic process after four cycling tests. This work provides a rational design of a metal cocatalyst–semiconductor channel for enhancing the photocatalytic HER under visible light.