High-Performance\nPhotocatalytic Hydrogen Generation\nUsing Robust Dianchoring Photosensitizers

A novel\nseries of donor–donor−π–acceptor\n(D–D−π–A) 9,9′-dihexylfluorene-based\ndianchoring organic dyes, each featuring distinct bridging electron-donating\nmoieties, have been synthesized and characterized. Their performances\nin photocatalytic hydrogen evolution (PHE) were evaluated, taking\ninto account of their photophysical and electrochemical attributes.\nRemarkably, <b>(</b><i><b>Z</b></i><b>)-3-(5-(4-((4-(5-((</b><i><b>E</b></i><b>)-2-carboxy-2-cyanovinyl)thiophen-2-yl)phenyl)(9,9-dihexyl-</b><i><b>9H</b></i><b>-fluoren-2-yl)amino)phenyl)thiophen-2-yl)-2-cyanoacrylic\nacid</b> achieved an active and robust H<sub>2</sub> generation\nsystem with a turnover number (TON) of up to 17 400 in 126\nh, with a production of 1090 μmol (26.3 mL) of hydrogen. The\ninitial turnover frequency (TOF<sub>i</sub>), initial activity (activity<sub>i</sub>), and initial apparent quantum yield (AQY<sub>i</sub>) were\n808 h<sup>–1</sup>, 505 mmol g<sup>–1</sup> h<sup>–1</sup>, and 8.65%, respectively, under visible light irradiation in water.\nThis photosensitizer is considered one of the most effective and durable\nsystems for photocatalytic hydrogen production that attached to molecular\nPt-TiO<sub>2</sub>, as stated out in the literature using organic\ndyes under visible light, when compared the TOF and TON values. The\nexperimental results demonstrated that the dianchoring dyes with bridging\nunits could significantly enhance PHE performance, maintaining justifiable\ndurability over prolonged irradiation.