Hierarchical interface engineering of PANI nanowires on Bi2O3 nanoflower scaffolds for highly efficient overall water splitting: Mechanistic insights and performance evaluation

The development of efficient and durable bifunctional electrocatalysts is essential for scalable alkaline water electrolysis processing. Herein, a binder-free bismuth oxide/polyaniline (Bi 2 ​O 3 /PANI) composite is constructed featuring a novel “nanowire-on-nanoflower” architecture, where polyaniline nanowires are conformally integrated onto 3D Bi 2 ​O 3 nanoflowers. This highly accessible interfacial network drives active interfacial charge modulation. Benefiting from this strong electronic buffering, the composite delivers exceptional bifunctional activity, requiring overpotentials of only 87 mV for the hydrogen evolution reaction (10 mA cm −2 ) and 386 mV for the oxygen evolution reaction (OER) (200 mA cm −2 ), alongside remarkable extended durability for 100 h. A full Bi 2 ​O 3 /PANI electrocatalyzer requires just 1.6 V to reach 10 mA cm −2 . Density functional theory confirms that PANI acts as an active electron donor, driving interfacial charge redistribution and p-band modulation. This optimizes hydrogen adsorption toward near-thermoneutral energetics, lowers the OER barrier, and structurally protects the active sites, highlighting a transformative design for robust organic–inorganic electrocatalysts.