Vertically Aligned Metal-Organic Framework Derived from Sacrificial Cobalt Nanowire Template Interconnected with Nickel Foam Supported Selenite Network as an Integrated 3D Electrode for Overall Water Splitting

The development of bifunctional, highly active electrocatalysts for an overall water splitting reaction remains a major challenge. Here, the sacrificial template-assisted transformation of cobalt hydroxide nanowire (Co(OH)₂ NW) into a metal-organic framework network (MOF) is conceived as a porous structure that provides extremely active and durable electrochemical energy conversion characteristics. After this, the 1D MOF modified Co NWs can be further transformed into a hybrid structure (MOF CoSeO₃ NWs) by selenization. The self-template transformation strategy allows the interconnected porous conductive network to be exposed to abundant reactive sites and to improve electronic conductivity/structural integrity. Thus, the obtained catalyst established by electrocatalytic activity in the course of the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) in 1 M KOH solution requires overpotentials (η) of 290 and 150 mV to achieve a current density of 50 and 10 mA cm^-2 for both OER and HER. Interestingly, as a full cell water electrolyzer (MOF CoSeO₃ NWs (+) // MOF CoSeO₃ NWs (-)), the MOF CoSeO₃ NW's modified electrode exhibits an affordable cell voltage of 1.675 V at a current density of 100 mA cm^-2. This work involves a viable and systematic strategy to prepare many other functional integrated MOFs that can be used for energy storage and conversion in multiple applications.