New picolinate-functionalized titanium-oxide clusters: syntheses, structures and photocatalytic H 2 evolution.

Two nanosized titanium-oxide clusters (TOCs), Ti 12 (μ 2 -O) 14 (μ 3 -O) 4 PA 16 (1; PA = 2-picolinate) and Ti 12 (μ 2 -O) 18 PA 18 (2) were synthesized by using 2-picolinic acid and Ti(O i Pr) 4 in one-pot reactions. Their structures were determined using single-crystal X-ray diffractometry. Although both have the same core composition of Ti 12 O 18 , 1 exhibited superior H 2 evolution activity of up to 180 μmol h -1 g -1 , which is nearly eight times faster than 2. Mechanism studies revealed that 1 could induce the assembly of 2.3 nm PtNPs into 10-30 nm supra-nanoparticle structures, which contributed to the increased H 2 evolution rate.