Ag nanoparticles anchored organic/inorganic Z-scheme 3DOMM-TiO_2–x-based heterojunction for efficient photocatalytic and photoelectrochemical water splitting

Narrow spectral response, low charge separation efficiency and slow water oxidation kinetics of TiO₂ limit its application in photoelectrochemical and photocatalytic water splitting. Herein, a promising organic/inorganic composite catalyst Ag/PANI/3DOMM-TiO_2–x with a three-dimensional ordered macro-and meso-porous (3DOMM) structure, oxygen vacancy and Ti³⁺ defects, heterojunction formation and noble metal Ag was designed based on the Z-scheme mechanism and successfully prepared. The Ag/PANI/3DOMM-TiO_2–x ternary catalyst exhibited enhanced hydrogen production activity in both photocatalytic and photoelectrochemical water splitting. The photocatalytic hydrogen production rate is 420.90 μmol g^–1 h^–1, which are 19.80 times and 2.06 times higher than the commercial P25 and 3DOMM-TiO₂, respectively. In the photoelectrochemical tests, the Ag/PANI/3DOMM-TiO_2–x photoelectrode shows enhanced separation and transfer of carriers with a high current density of 1.55 mA cm^–2 at equilibrium potential of 1.23 V under simulated AM 1.5 G illumination, which is approximately 5 times greater than the 3DOMM-TiO₂. The present work has demonstrated the promising potential of organic/inorganic Z-scheme photocatalyst in driving water splitting for hydrogen production.