Calix[4]arene based dye-sensitized Pt@UiO-66-NH2 metal-organic framework for efficient visible-light photocatalytic hydrogen production

- Low-cost Calix-3 dyes were firstly applied in photocatalytic H2 production.
- Calix-3-sensitized Pt@UiO-66-NH2 catalysts have the extremely low Pt loading.
- Calix-3-sensitized Pt@UiO-66-NH2 catalysts exhibit high H2 production activity.
- Calix-3-sensitized Pt@UiO-66-NH2 catalysts perform excellent long-term stability.

A cone-calix[4]arene dye Calix-3 with four D-π-A units has been utilized to sensitize Zr-containing metal-organic framework (MOF) embedded with Pt particles, denoted as Pt@UiO-66-NH2, for photocatalytic H2 production under visible light irradiation. The structures of UiO-66-NH2, Pt-loadings, and dye-adsorbed amounts of these photocatalysts are optimized. Comparatively, Calix-3-sensitized Pt@UiO-66-NH2 catalysts with 0.65 wt% of Pt loading and 15.7 μmol/g of Calix-3 dye amount exhibit much higher hydrogen production activity (1528 μmol g−1 h−1 based on the mass of MOF or 236 mmol g−1[Pt] h−1 based on Pt mass) than that sensitized by single D-π-A M-3 dyes (516 μmol g−1 h−1 or 24 mmol g−1[Pt] h−1) under the similar photocatalytic conditions, and perform excellent stability during the long-term tests simultaneously. In view of the extremely low Pt loading, the activity based on Pt mass is one of the highest among all the reported MOF-based photocatalytic hydrogen production systems. The enhancement in hydrogen evolution efficiency and stability could be ascribed to lower tendency for aggregation, higher molar absorption coefficients, more efficient electron transfer, and better intrinsic and adsorbed stability of Calix-3 dyes. This work provides useful insights for future design and synthesis of new functional dye sensitization MOF system for photocatalytic hydrogen production.

Calix-3-sensitized Pt@UiO-66-NH2 catalysts with low-cost Calix-3 dye and extremely low Pt loading exhibit an impressive visible-light photocatalytic hydrogen production activity and excellent stability during the long-term tests simultaneously.148