Morphology-dependent photoelectrocatalytic water oxidation for H2 production: Superior performance of dual-structured zinc vanadate over nickel and copper analogues
A comprehensive study was conducted to explore the photoelectrochemical (PEC) water-splitting performance of metal vanadates, MeV2O6 (Me = Zn, Cu, Ni), with a focus on morphology optimization and structure-property relationships. Metal vanadates were synthesized using a conventional solid-state reaction method. X-ray diffraction (XRD) confirmed that ZnV2O6 has a monoclinic structure (C2/m space group), while NiV2O6 and CuV2O6 crystallize in triclinic structures (P¯ı space group). Vibrational mode analysis indicated similarities in the crystal structures of ZnV2O6 and CuV2O6, corroborated by their XRD patterns. SEM and XPS analyses revealed distinct surface morphologies and confirmed chemical homogeneity and oxidation states. The synthesized nickel vanadate (NV), copper vanadate (CV), and zinc vanadate (ZV) photoelectrodes exhibited unique morphologies: capsule-like structures for NV, agglomerated flakes for CV, and a combination of nanosheets and nanorods for ZV. The hierarchical architecture of ZV provided superior PEC performance, achieving a photocurrent density of 9.83 mA cm⁻², which was 16.94 and 2.43 times higher than NV (0.58 mA cm⁻²) and CV (4.03 mA cm⁻²), respectively. This enhancement was attributed to ZV’s dual morphology, which facilitated a higher surface area, efficient charge transport, and improved mass transfer kinetics. Additionally, ZV demonstrated a favorable onset potential of 0.431 V, significantly lower than NV (0.798 V) and CV (0.522 V), along with an applied bias photonto-current efficiency ABPE) of 1.35 %. Stability tests showed that ZV retained 91.6 % of its initial photocurrent density over 21000 s of continuous illumination, with post-stability performance improving further to 11.48 mA cm⁻². These findings highlight the critical role of hierarchical nanostructures in enhancing PEC performance,
underscoring the potential of morphology-engineered metal vanadates for efficient PEC water oxidation applications.
A comprehensive study was conducted to explore the photoelectrochemical (PEC) water-splitting performance of metal vanadates, MeV2O6 (Me = Zn, Cu, Ni), with a focus on morphology optimization and…
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