New picolinate-functionalized titanium-oxide clusters: syntheses, structures and photocatalytic H2 evolution

Abstract

Two nanosized titanium-oxide clusters (TOCs), Ti₁₂(μ₂-O)₁₄(μ₃-O)₄PA₁₆ (1; PA = 2-picolinate) and Ti₁₂(μ₂-O)₁₈PA₁₈ (2) were synthesized by using 2-picolinic acid and Ti(OⁱPr)₄ in one-pot reactions. Their structures were determined using single-crystal X-ray diffractometry. Although both have the same core composition of Ti₁₂O₁₈, 1 exhibited superior H₂ 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 H₂ evolution rate.