A Bifunctional 2D Interlayered β-Cu₂V₂O₇/Zn₂V₂O₆ (CZVO) Heterojunction for Solar-Driven Nonsacrificial Dye Degradation and Water Oxidation

Investigating novel materials with controlled morphology for solar-driven conversions is the foremost research emphasis in applied sciences. In continuation of those efforts, we report the unique synthesis of a novel trimetallic β-Cu₂V₂O₇/Zn₂V₂O₆ (CZVO) hybrid with controlled morphology. The trimetallic CZVO demonstrates a bifunctional, non-sacrificial photoresponse in the cases of 1) photocatalytic degradation using methylene blue (MB) as a model dye; and 2) photoelectrochemical (PEC) water oxidation. The X-ray photoelectron spectroscopy (XPS) analysis of CZVO confirmed Type-(I) heterojunction formation between β-Cu₂V₂O₇ (CVO) and Zn₂V₂O₆ (ZVO). After visible light exposure (65 min), CZVO-opt (1 wt% CVO: 5 wt% ZVO) demonstrated the highest photodegradation, while the CZVO-opt photoanode delivered the highest photocurrent density (I _ph) of 1.78 mA cm⁻² at 1.23 V_RHE, almost 3.11 and 1.55 times more than CVO (I _ph = 0.57 mA cm⁻²) and ZVO (I _ph = 1.15 mA cm⁻²) photoanodes, respectively. The CZVO-opt photoanode harvested the most solar energy in terms of incident photon to current conversion efficiency (IPCE_{320 nm} = 37.93%). The significant improvement in the CZVO-opt performance can be attributed to the firm contact and uniform distribution of ZVO NPs over CVO interlayered nanosheets, which leads to adequate solar absorption and facile charge transport through a Type-(I) heterojunction with suppresses charge recombination.