Photocatalysts for H2 Generation from Starburst Triphenylamine/Carbazole Donor‐Based Metal‐Free Dyes and Porous Anatase TiO2 Cube

A series of novel triphenylamine/carbazole‐based D–D–π–π–A dyes DH1–4 and a mesoporous anatase cubic “microcage” TiO2 material (denoted as MC‐TiO2) were synthesized and combined to obtain dye‐sensitized photocatalysts (denoted as DHn/Pt/MC‐TiO2, n=1–4). These catalysts showed better performances in visible‐light‐driven H2 evolution from water than DHn/Pt/P25‐TiO2 catalysts based on commercial P25‐TiO2 bulk semiconductor under similar conditions. Compared with P25‐TiO2 particles, the porous MC‐TiO2 had a large Brunauer–Emmett–Teller surface area, porosity, and exposed {0 0 1} crystal plane, which greatly contributed to the photocatalytic activity. The optimized DH2/Pt/MC‐TiO2 photocatalyst exhibited an attractive H2 production rate (16.28 mmol g−1 h−1 based on catalyst mass), and the optimized DH4/Pt/MC‐TiO2 photocatalyst showed good stability [turnover number (TON) of 16 699 in 105 h based on dye number], which represents one of the best performances among all reported visible‐light‐driven heterogeneous catalytic systems. Compared with the other dyes in this series, the high H2 production rate of DH2 on Pt/MC‐TiO2 can be attributed to its size‐matching effect and thus high dye loading amount, whereas the high TON and durability of DH4/Pt/MC‐TiO2 are probably related to the rapid regeneration kinetics of DH4. Coming out of their cage: A series of highly robust hybrid catalysts DHn/Pt/MC‐TiO2 (n=1–4) based on D–D–π–π–A metal‐free dyes DH1–4 and an anatase cubic mesoporous microcage TiO2 are prepared. The catalysts display efficient and persistent photocatalytic water splitting activities (turnover number=16 600 in 105 h for DH4/Pt/MC‐TiO2).