Ternary CdS/Au/3DOM-SrTiO₃ composites with synergistic enhancement for hydrogen production from visible-light photocatalytic water splitting

New ternary composites based on three dimensionally ordered macroporous (3DOM) SrTiO₃ (CdS/Au/3DOM-SrTiO₃) were prepared and used as photocatalysts in visible light (λ > 420 nm) photocatalytic water splitting for hydrogen evolution. Through optimizing the pore size of 3DOM-SrTiO₃ materials and the loading amounts of Au and CdS, CdS/Au/3DOM-SrTiO₃(300), templated by 300 nm sized poly(methyl methacrylate) colloids, was found to exhibit a remarkably enhanced photocatalytic hydrogen evolution rate (2.74 mmol/h•g), which was 3.2 times as high as that of CdS/Au/C-SrTiO₃ catalyst based on commercial SrTiO₃. This notably enhanced photocatalytic performance was mainly attributed to the slow photon enhancement effect of 3DOM-SrTiO₃(300) material, which significantly promoted the light harvesting efficiency of ternary composite for the slow photon region of 3DOM-SrTiO₃(300) was well matched with the optical absorption band of photocatalyst. Further depositing Pt nanoparticles on CdS/Au/3DOM-SrTiO₃(300) composite as a co-catalyst, an extraordinarily high hydrogen evolution rate (up to 5.46 mmol/g•h) and apparent quantum efficiency (42.2% at 420 nm) were achieved because of the synergistic effect of efficient carrier separation, Au SPR effect, and slow photon effect. Furthermore, these ternary CdS/Au/3DOM-SrTiO₃ composite photocatalysts were very stable and could be easily recycled four times in visible light photocatalytic water splitting experiments without any loss in activity.