Paper-Based Origami Photoelectrochemical Sensing Platform with TiO2/Bi4NbO8Cl/Co-Pi Cascade Structure Enabling of Bidirectional Modulation of Charge Carrier Separation

High Resolution Image Download MS PowerPoint Slide A bidirectional modulation of photoinduced charge carrier separation strategy based on TiO 2 /Bi 4 NbO 8 Cl/Co-Pi was proposed in microfluidic paper based photoelectrochemical analytical device (μ-POAD). Perovskite Bi 4 NbO 8 Cl with high charge carrier mobility was employed as visible light absorber, sandwiching between electron transporting material (ETM) and hole transporting material (HTM). Paper based TiO 2 nanosheet arrays (PTNAs) serve as the ETM to provide a direct pathway for electron transport and Co-Pi works as the HTM to extract holes. Driven by a built-in electric field, the generated electrons of Bi 4 NbO 8 Cl are extracted by PTNAs, while holes are drawn toward Co-Pi, achieving efficient carrier separation. Remarkably, it is the first time that the HTM was introduced into μ-POAD to efficiently output holes and enhance the sensitivity. With the aid of ETM and HTM, 2.59 and 14.6 times higher photocurrent density was obtained compared with PTNAs/Bi 4 NbO 8 Cl and Bi 4 NbO 8 Cl photoelectrode, respectively. Benefiting from this dramatic photocurrent signal, ultrasensitive detection of β human chorionic gonadotrophin is realized with the linear range of 0.01–3000 IU L –1 and detection limitation of 0.005 IU L –1 . This work demonstrates the importance of efficient carrier separation to the sensitivity of μ-POAD and paves the way for developing a high-performance analytical device.