Structurally-New Hexadecanuclear Ni-Containing Silicotungstate with Catalytic Hydrogen Generation Activity.

A structurally-new, carbon-free hexadecanuclear Ni-containing silicotungstate, [Ni 16 (H 2 O) 15 (OH) 9 (PO 4 ) 4 (SiW 9 O 34 ) 3 ] 19- , has been facilely synthesized using a one-pot, solution-based synthetic method systematically characterized by single-crystal X-ray diffraction and several other techniques. The resulting complex works as a noble-metal-free catalyst for visible-light-driven catalytic generation of hydrogen, by coupling with a [Ir(coumarin) 2 (dtbbpy)][PF 6 ] photosensitizer and a triethanolamine (TEOA) sacrificial electron donor. Under minimally optimized conditions, a turnover number (TON) of 842 was achieved for TBA- Ni 16 P 4 (SiW 9 ) 3 -catalyzed hydrogen evolution system. The structural stability of TBA- Ni 16 P 4 (SiW 9 ) 3 catalyst under photocatalytic conditions was evaluated by the mercury-poisoning test, FT-IR, and DLS measurements. The photocatalytic mechanism was elucidated by both time-solved luminescence decay and static emission quenching measurements.