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 TiO₂ microspheres was grown in situ on a Ti substrate (PDAP-3DTiO₂MSs/Ti) and used as photoanode for water oxidation in alkaline media under AM 1.5G illumination. The PDAP-3DTiO₂MSs/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-3DTiO₂MSs/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-3DTiO₂MSs/Ti should benefit from the coexistence of Ti³⁺ and Ti⁴⁺ in 3DTiO₂MSs, the light harvest capability of PDAP and the type II heterojunction formed between 3DTiO₂MSs and PDAP, which result in the enhanced generation and separation of photocarriers.

光电催化（PEC）分解水为直接生产太阳能提供了一种替代方法。在这项研究中，共轭聚合物[poly-2,6-diaminopyridine（PDAP）]和三维TiO ₂微球之间形成的新型异质结构在Ti衬底（PDAP-3DTiO ₂ MSs / Ti）上原位生长并使用作为光阳极，用于在AM 1.5G光照下在碱性介质中水氧化。PDAP-3DTiO ₂ MSs / Ti在0.44 V vs. Pt时可产生0.85％的施加偏压光子-电流效率， 在1.23 V vs. RHE时可产生1.56 mA cm ^-2的光电流密度。此外，PDAP-3DTiO ₂MSs / Ti显示出令人印象深刻的光电化学稳定性，反应4小时后保留了其初始光电流的93％。基于物理化学特征和光/电化学测量，PDAP-3DTiO ₂ MSs / Ti的优异PEC水分解性能应受益于3DTiO ₂ MS中Ti ³⁺和Ti ⁴⁺的共存，即光收集PDAP的功能以及3DTiO ₂ MS与PDAP之间形成的II型异质结，从而增强了光载流子的产生和分离。