Design and construction of a novel hierarchical Ag/{1 1 1}Ag₃PO₄/PANI/Pt photoanode with boosted interfacial charge transfer rate and high photocurrent density > 16 mA/cm² for sunlight-driven water splitting

In this work, a novel hierarchical photoanode structure of Ag/{1 1 1}Ag₃PO₄/PANI/Pt was synthesized, demonstrating a novel and facile approach to design a high-performing Ag₃PO₄-based photoanode for visible-light-driven solar green hydrogen (H₂) generation. The Ag₃PO₄ photoanode with carefully curated active facets, Ag/{1 1 1}Ag₃PO₄, was interfaced with a conductive polyaniline (PANI) thin film and surface decorated with platinum nanoparticles (Pt NPs) to realise the combined advantages of integrating both PANI and Pt NPs as a hole-transporting layer and co-catalysts, respectively. This novel photoanode achieved a record photocurrent density of 16.34 mA/cm² at 1.4 V vs Ag/AgCl under AM 1.5 G solar irradiation (100 mW/cm²), which outperformed that of the bare Ag/{1 1 1}Ag₃PO₄ photoanode and is also the highest photocurrent density reported to date for Ag₃PO₄-based photoanodes. The PEC enhancement is attributed to the new exploitation of the PANI-{1 1 1}Ag₃PO₄ p-n heterojunction, the hole-transporting property of PANI and the electron-capturing capability of Pt NPs, in which their synergetic interactions effectively led to improved light absorption, enhanced charge separation and reduced charge recombination. It is foreseen that this current work can provide a base for further nanoarchitectural design strategies to construct efficient photoanodes used in PEC water splitting application.