Bilayered nano-hetero-structured n/n junction thin-film electrodes, WO₃/Yb-Mo-BiVO₄, for efficient photoelectrochemical water splitting

Abstract: Significant advancement in photoelectrochemical water splitting current is observed using uniquely evolved n/n junction bilayered nano-hetero-structured thin films, WO₃/Yb-Mo-BiVO₄, as photoanode. Films, synthesized over F:SnO₂ glass substrates were characterized by UV–Visible spectroscopy, X-ray diffractometry, atomic force microscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Using thin films (2% Mo and 4% Yb incorporation) as working electrode in PEC cell, in conjunction with platinum counter electrode, saturated calomel reference electrode, aqueous solution (200 cm³) of K₂HPO₄ (1.0 M, pH 8.7, temperature 31 ± 3.6 ℃) and 150 W Xenon Arc lamp for illumination, ~ 227–950% increase in I_ph is recorded against monolayered pristine films of WO₃ and BiVO₄. Marked rise in photoelectrochemical cell photocurrent is attributable to expanded absorption of light, coupled with internal electric field in Yb–Mo-incorporated n/n hetero-junction films, reduced electrical resistivity and optimally raised surface roughness that favoured the separation and transfer of photogenerated charge carriers across electrode/electrolyte interface. Graphical Abstract: [Figure not available: see fulltext.]