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

A cone-calix[4]arene dye Calix-3 with four D-pi-A units has been utilized to sensitize Zr-containing metal organic framework (MOP) embedded with Pt particles, denoted as Pt@UiO-66-NH2, for photocatalytic H-2 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 mu mol/g of Calix-3 dye amount exhibit much higher hydrogen production activity (1528 mu mol 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-pi-A M-3 dyes (516 mu mol g(-1) h(-1) or 24 mmolg(-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. (C) 2017 Elsevier B.V. All rights reserved.