Enhancing efficiency of photoelectrochemical water splitting using zinc vanadate nanosheets (ZV) on manganese vanadate needle flowers (MV) supported by carbon nanofibers

Abstract

Zinc and Manganese vanadates are highly regarded as potential photoanode materials for photoelectrochemical (PEC) water splitting due to their limited bandgap, varying optical and electrical characteristics based on their composition, and robust nature. To advance the practical use these materials, it is essential to creating precisely composed and structured Zinc and Manganese vanadates to enhance their overall effectiveness. In this work, we employed various morphologies, such as nanobelt flower like Zinc vanadate (ZV), nano-needle like Manganese vanadate (MV), a composite with ZV and MV, and a ZV-MV@CNF ternary composition. These novel morphologies grown on ITO substrate using a simple, hydrothermal approach without using any seed layer. The structural, surface, and optical examinations confirmed that the ZV-MV@CNF catalyst had superior visible light absorption, accelerated charge transfer, heterojunction interface between ZV and MV, and increased electron mobility, leading to outstanding photoelectrochemical performance. The photocurrent density of the ZV-MV@CNF photoanode reached 6.59 mA cm−2 at 1 V versus Ag/AgCl in a 0.25 M KOH solution under the illumination light. These results are ∼3.00, 3.52, and 1.28 times greater than the pristine ZV, MV, and ZV-MV, respectively. The fine-tuned ZV, MV, ZV-MV, and ZV-MV@CNF electrodes showed applied bias photon to current efficiency (ABPE) values of 0.09 %, 0.06 %, 0.14 %, and 0.18 %, respectively. The improved photoelectrochemical behavior of the ZV-MV@CNF electrode is credited to the excellent light absorption, and the remarkable catalytic and charge transport capabilities of CNFs. Therefore, these experimental results and characterization analysis suggested that advanced hierarchical nanostructures hold significant promise for water splitting applications.