Noble-metal free photocatalytic hydrogen generation of CuPc/TiO2 nanoparticles under visible-light irradiation

CuPc/TiO2 photocatalyst composite is successfully synthesized by a facile solution method and applied for photocatalytic hydrogen production for the first time. The amorphous CuPc coating layer plays the crucial role in standout photocatalytic activity in terms of visible-light absorption, recombination suppression, and charge transfer enhancement. The CuPc/TiO2 photocatalyst composites exhibit efficient and stable visible-light driven photocatalytic hydrogen production without the aid of cocatalysts. [Display omitted] •Demonstrated CuPc/TiO2 composites for photocatalytic water splitting for the first time.•Enhanced charge transfer and photoresponse by the amorphous CuPc coating.•Presented quantitative analysis of charge transfer dynamics for solar water splitting.•Showed active and stable visible-light photocatalytic water splitting without cocatalysts. Development of visible-light activated photocatalysts is highly important but challenging for photocatalytic reactions. In addition, noble-metal cocatalysts are crucially required for efficient charge transfer in most solar water splitting reactions. In the present study, we have synthesized copper phthalocyanine (CuPc) supported TiO2 photocatalyst composites by a facile solution reaction and demonstrated their efficient photocatalytic hydrogen generation under visible-light irradiation. The amorphous CuPc coating layer plays key roles in solar water splitting in terms of efficient separation of the photogenerated charges and high absorption in visible-light region. More surprisingly, our CuPc/TiO2 does not demand any noble-metal cocatalyst for exhibiting high photocatalytic activity with 6.68% of apparent quantum yield (AQY) at 420 nm. Moreover, several continuous runs of hydrogen generation using CuPc/TiO2 composite proved the high durability of our products. The detailed charge transfer dynamics of CuPc/TiO2 composites by time-resolved photoluminescence (TRPL) demonstrated that our noble metal-free CuPc/TiO2 shows a comparably high charge transfer efficiency as that of Pt cocatalyst modified samples. On the basis of the analysis, a possible mechanism for visible-light driven photocatalytic hydrogen generation of CuPc/TiO2 composites is postulated. Our study suggests that CuPc/TiO2 is a highly efficient and stable photocatalyst for solar water splitting even without noble-metal cocatalysts.