Efficient and Stable MoO_X@Mo-BiVO₄ Photoanodes for Photoelectrochemical Water Oxidation: Optimization and Understanding

Abstract

In this study, we propose a facilely dip-coated and intermediate heat-treated MoO X @Mo-BiVO4 photoanode that displays extremely efficient and stable photoelectrochemical H2 production. The formation of MoO X as an intermediate species is investigated using time of flight-secondary ion mass spectrometry (TOF-SIMS). The MoO X @2% Mo-BiVO4 photoanode exhibited a photocurrent density of approximately 1 mA cm–2 at 1.23 V versus the reversible hydrogen electrode (RHE), which was 5.5 times higher when compared with that of the BiVO4 photoelectrode because of the formation of MoO X and the induced oxygen vacancies (VOs), which are beneficial for the suppression of electron–hole recombination. The incident photon current efficiency of approximately 17.7% for the MoO X @2% Mo-BiVO4 photoanode is a noticeable improvement over the pure BiVO4 photoelectrode. The H2 and O2 productions of the MoO X @2% Mo-BiVO4 photoanode after 2 h were 32.46 and 15.85 μmol cm–2, respectively, which reached approximately 85% Faradaic efficiency, at 1.23 V versus RHE under 100 mW/cm2.

Polarization Boosted Solar H2O2 Production over Quantum Dot-Decorated Nanosheets with Rich Oxygen Vacancies

“…The peak centered at 306 cm –1 is assigned to the stretching or bending vibrations of Bi–O bonds and the WO 6 octahedron. ,,− The Raman bands of q-BiVO 4 at around 323 and 363 cm –1 are observed, which are typical vibrational bands of BiVO 4 . Other distinguished Raman bands at around 705 and 826 cm –1 are ascribed to the antisymmetric stretching vibration mode and the symmetric bending vibration mode of the V–O bond for the tetragonal phase. − The characteristic peaks of Bi 2 WO 6 (306, 700, 792, and 815 cm –1 ) and BiVO 4 (363 and 705 cm –1 ) in W-0.30V are detected. However, the characteristic peaks of W-0.3V present a broadening at 792 and 815 cm –1 , which signify an increased number of crystal defects in W-0.3V .…”

Elucidating the Epitaxial Growth Mechanisms of Solution-Derived BiVO4 Thin Films Utilizing Rapid Thermal Annealing

“…Another advantage of the metal–organic decomposition method is the facile incorporation of external dopants, which is frequently employed for improving the electrical conductivity and photoelectrochemical performance of BiVO 4 . ,, For PLD, individual ceramic targets must be prepared for each dopant and doping concentration in advance. In contrast, the chemical compositions of the BiVO 4 precursor solutions can be easily adjusted at a much lower cost.…”

Unveiling the Significance of Diverse Valence State Second Dopants on Hf-Doped Fe2O3 Photoanodes for Enhanced Photoelectrochemical Water Splitting

“…The extended τ el seen in this study can be attributed to the passivation of surface defects, which in turn enhances the transfer of photogenerated charge carriers. 38,39 OCP curves were used to assess the band bending and charge transfer at the photoanode−electrolyte interface of the photoanodes (Figure 3f). The open-circuit photovoltage (V ph ), which represents the potential difference between the OCP in the dark and under light illumination, can be used to estimate the increase in the band bending degree.…”