Surface modification of metal-organic frameworks under sublimated iron-atmosphere by controlled carbonization for boosted oxygen evolution reaction

Development of cost-effective, efficient, and durable electrocatalysts for oxygen evolution reaction (OER) with fast kinetic reaction is highly significant, considering the elevated thermodynamic energy barrier involved in water electrolysis. To overcome such challenges, an innovative vapor phased iron-doping strategy is employed on carbon nanotubes (CNT)-interlinked metal-organic framework (MOF) nanosheets (Ni-MOF@CNT) to obtain mixed metal oxide and metal heteronanoparticles superficially implanted partially (semi)-decomposed MOF nanosheets (Ni-M@C-400). These semi-MOF nanosheets attain the structural privileges related to MOF-nanostructure, mixed metal nanoparticles synergism, interconnected-CNT assisted high conductivity, and mechanical strength. As a result, Ni-M@C-400 exhibits exceptional OER activity with overpotential as low as 229 mV to reach the benchmark current density of 10 mA/cm² (η₁₀) and exhibits greatly reduced thermodynamic barrier (Tafel slopes of 40.51 mV/dec) along with significant durability for ~ 60 h. More importantly, this sublimated iron-doped semi-MOF (Ni-M@C-400) displays significantly better OER performance over the corresponding annealed bimetallic MOF (NiFe-M@C-400: 270 mV at η₁₀). Moreover, the successful incorporation of vapor phased iron into variety of MOFs (Cr, Mn, Co, Ni, and Cu) approved its uniqueness and the universality. This work provides an innovative vapor phased heteroatom-doping strategy to develop cost-effective and efficient electrocatalysts for water electrolysis.