Enhanced photocatalytic hydrogen production over conjugated polymer/black TiO2 hybrid: The impact of constructing active defect states

Abstract

Utilization of noble metal (e.g. Pt, Au) as co-catalyst seems always indispensable for a photocatalytic H2 production catalyst because most semiconductors lack sufficient active sites. Herein, some non-noble metal active states, Ti3+/Ov (oxygen vacancies) and surface amorphization structure, are introduced into anatase TiO2 nanoparticles by ball milling them with TiH2 to prepare black TiO2. And then, an organic/inorganic hybrid (BE-black TiO2) containing a conjugated polymer (BE, a modified poly- benzothiadiazole flake) and black TiO2 is fabricated and investigated for photocatalytic H2 production without noble metal co-catalyst. Compare to BE-TiO2 catalyst, the BE-black TiO2 exhibit a ∼ 30% enhancement for H2 production activity under visible light (λ > 420 nm) irradiation. Combining the structural characterizations, comparison of H2 production rate and electron transfer behavior analysis, it is found that these active states play key role in the enhancement of photoactivity through narrowing the band-gap of TiO2, accelerating photoelectrons transfer from BE to TiO2, acting as electron traps and reaction sites for H2 production.