The facile and cost-effective designing of electrocatalysts still remains a challenge for electrochemical water oxidation. In the last three decades, a series of earth-abundant transition metal-based electrocatalysts have been explored for electrochemical water oxidation. In this regard, metal–organic framework (MOF) derived catalysts (metal oxides, phosphides, chalcogenides, etc.) with various compositions, desired morphologies, high porosity, large electrochemical surface areas, and tunable properties have been explored for electrochemical water oxidation. MOF-derived catalysts produce excellent electrochemical water oxidation activity in alkaline medium. However, the direct utilization of MOFs for anodic water oxidation has been overlooked for a long time due to their poor stability under electrochemical conditions. Recently, the instability of MOFs has been successfully utilized to produce ultrathin metal hydroxide–(oxy)hydroxide [M(OH)₂–M(O)_x(OH)_y] nanosheets by electrochemical transformation. The MOF plays the role of a precatalyst and undergoes a series of structural reconstructions like hydrolysis, metal ion leaching, oxidation of the metal ions during alkaline anodic water oxidation and forms the active catalyst M(OH)₂–M(O)_x(OH)_y. The electrochemically synthesized ultrathin nanosheets demonstrate excellent water oxidation activity and stability because of their atomic-level thickness, large electrochemical surface area, optimum inter-layer distance, and tuned electronic structure. Recently, this strategy has been explored to attain high-quality ultrathin M(OH)₂–M(O)_x(OH)_y nanosheets for water oxidation. Although tremendous progress has been made in using MOFs as a precatalyst for electrochemical water oxidation, no dedicated review is available in this field. Looking at this point, this review describes a strategy of designing ultrathin M(OH)₂–M(O)_x(OH)_y nanosheets by the electrochemical transformation of MOFs, the structural and electronic structure modulation of the ultrathin M(OH)₂–M(O)_x(OH)_y nanosheets, morphological development and their application for electrochemical water oxidation. Moreover, the structure–activity–stability relationship has been established with suitable examples and the recent progress and challenges have also been addressed focusing on the future perspective in this field.

Herein, we demonstrate a template directed route for the synthesis of self-supported cobalt–iron based Prussian blue analogues (PBAs). The PBAs are electrochemically transformed into layered double hydroxides to produce excellent water oxidation and hydrogen evolution activity, while the overall water splitting is attained at a cell voltage of 1.58 V to reach 20 mA cm⁻² current density.

To achieve efficient water splitting, it is essential to develop catalysts with high electrochemical performance, enhanced durability and tunable properties. Most of the transition metal‐based catalysts employed for the water splitting have been fabricated on the solid‐electrode support by using binder, which decreases the activity and durability of the catalyst system. In this respect, self‐supported metal organic framework (MOF) derived catalysts have been introduced with enhanced catalytic activity and mechanical stability for the electrochemical water splitting. The self‐supported MOF derived catalysts exhibit improved electronic conductivity, high electrochemical surface area, enhanced mechanical stability and strong catalyst‐support interaction. Moreover, these catalysts possess highly porous and hollow structure with designed morphology and multi‐metallic composition. Recently, a tremendous effort has been provided to explore this newly growing field and new dimensions and directions have been achieved. Looking at this point, we have described here the basic principles of catalyst design from self‐supported MOF, structural and interface engineering by controlling the electronic structure of the catalysts to improve the water splitting activity. In addition, the challenges and difficulties associated with this field have been pointed out and addressed for the future progress in this field.

Here, we demonstrate the enhanced water splitting activity of CoFe–LDH by vanadium substitution. Volcano plots are obtained for intrinsic water oxidation and hydrogen evolution with increasing vanadium substitution, and the best catalyst V_0.3–CoFe–LDH achieved 10 mA cm⁻² current density for H₂ and O₂ evolution merely at 98 mV and 240 mV overpotential, respectively.