A review on consequences of flexible layered double hydroxide-based electrodes: fabrication and water splitting application

Abstract

Electrocatalytic water splitting is considered the finest and the fastest way for the production of pure hydrogen with no emission of undesired by-products. The efficiency of this reaction is highly dependent on two different half-cell reactions, namely the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), hence it is necessary to develop robust, low cost, highly active, and earth-abundant electrocatalyst to catalyst HER and OER under low overpotential with high efficiency. In this regard, 3d transition metal-based layered double hydroxides (LDHs) are considered the best alternatives for Ru, Ir, or Pt metal-based counterparts. Although 2d transition metal based-LDH materials have made significant strides towards water splitting reaction, still some intrinsic drawbacks limit their application towards large-scale production. Major drawbacks of the LDHs are associated with structural destruction, insufficient ion transport, and less active sites, which makes it difficult to predict the kinetics of the reaction. Hence, to overcome such limitations various strategical modifications have been developed and the effectiveness of those modifications has increased the overall cell performance of the water electrolyzer, which is highly useful for the large-scale production of hydrogen. Hence, in this review, we elaborately discussed how the Ni, Co, and Fe-based bimetallic LDHs have been established as abundant, cheaper, and efficient electrode materials for the water splitting reaction. Further, we also stressed the basis of water electrolysis, mechanisms of OER and HER, and evolution parameters of such electrode materials toward the water splitting reaction.