Shape-Controlled First-Row Transition Metal Vanadates for Electrochemical and Photoelectrochemical Water Splitting

Transition metal vanadates (MVs) possess abundant electroactive sites, short ion diffusion pathways, and optical properties that make them suitable for various electrochemical (EC) and photoelectrochemical (PEC) applications. While these materials are commonly used in energy storage devices like batteries and capacitors, their shape-controlled 1D and 2D morphologies have gained equal popularity in water splitting (WS) technology in recent times. This review focuses on recent progress made on various first-row (3d, 4 s) transition metal vanadates (t-MVs) having controlled one-dimensional (fiber, wire, or rod) and two-dimensional (layered or sheet) morphologies with a specific emphasis on copper vanadates (CuV), cobalt vanadates (CoV), iron vanadates (FeV), and nickel vanadates (NiV). The review covers different aspects of shape-controlled 1D and 2D t-MVs including optoelectrical properties, wet chemistry synthesis, and electrochemical (EC-WS) and photoelectrochemical water splitting (PEC-WS) performance in terms of onset potential, overpotential, and long-term stability or high cyclic performance. The review concludes by providing some possible thoughts on how to promote the water-splitting attributes of shape-controlled t-MVs more effectively.