A heterostructured catalyst composed of poly-2,6-diaminopyridine and TiO2 microspheres used as a photoanode for efficient water splitting

Photoelectrocatalytic (PEC) water splitting provides an alternative to direct solar-to-fuel production. In this study, a novel heterostructure formed between a conjugated polymer [poly-2,6-diaminopyridine (PDAP)] and three-dimensional TiO 2 microspheres was grown in situ on a Ti substrate (PDAP-3DTiO 2 MSs/Ti) and used as photoanode for water oxidation in alkaline media under AM 1.5G illumination. The PDAP-3DTiO 2 MSs/Ti can produce applied bias photon-to-current efficiency of 0.85% at 0.44 V vs. Pt and a photocurrent density of 1.56 mA cm −2  at 1.23 V vs. RHE . Moreover, PDAP-3DTiO 2 MSs/Ti displays impressive photoelectrochemical stability with 93% of its initial photocurrent being retained after 4 h of reaction. Based on physical-chemical characterization and photo-/electro-chemical measurements, the superior PEC water splitting performance of PDAP-3DTiO 2 MSs/Ti should benefit from the coexistence of Ti 3+ and Ti 4+ in 3DTiO 2 MSs, the light harvest capability of PDAP and the type II heterojunction formed between 3DTiO 2 MSs and PDAP, which result in the enhanced generation and separation of photocarriers.