Hydrogen production via photocatalytic water splitting using spinel ferrite-based photocatalysts: Recent and future perspectives

The employment of limitless solar energy via semiconductor-facilitated photocatalysis represents a sustainable strategy for addressing the worldwide energy crisis and escalating environmental concerns. Thus, the advancement of effective photocatalysts represents a significant approach in addressing the energy crisis and environmental challenges. Spinel ferrites, with the general formula of MFe₂O₄ (M is a divalent metal ion such as Mg²⁺, Mn²⁺, Zn²⁺, Ni²⁺, Co²⁺, Cu²⁺, etc.), have attracted considerable research interest. Interesting physicochemical properties such as narrow bandgap, magnetic recyclability, large surface area, excellent photoactivity, non-toxicity, earth-abundance, easy synthesis, stability, and other exciting properties have seen spinel ferrites emerged as suitable candidates for photocatalytic hydrogen fuel generation. For these reasons, this review attempts to provide an overview of the application of spinel ferrites in photocatalytic hydrogen fuel generation. Herein, latest research conducted in the last decade on the use of spinel ferrite as main and co-catalyst in photocatalytic hydrogen production has been reviewed. Attention has been paid to the crystal structure, prospects and shortcomings as photocatalysts, and synthesis methods, including advantages and disadvantages of various synthesis approaches of spinel ferrites. Moreover, the pathways to improve the performance and efficiency of spinel ferrites for effective water splitting are highlighted in this review. Finally, current challenges, future outlook, suggestions and research gaps in the use of spinel ferrites in photocatalytic hydrogen evolution reaction have also been highlighted. The primary objective of this review is to demonstrate that spinel ferrites are regarded as a significant semiconductor photocatalyst due to their efficient absorption of visible light, suitable band alignment, and magnetic recyclability. This review offers a thorough understanding of spinel ferrite-based photocatalysts, encompassing recent research discoveries and progresses. It is envisioned that further investigations should focus on improving photocatalytic performance of spinel ferrites via construction of heterojunction and modifying synthesis processes.