Layered MOF supported on 2D delaminated MXene (Mo2Ti2C3) nanosheets boosted water splitting

Abstract

Metal organic frameworks (MOFs) have a porous structure, high surface area, and high charge transfer, and they have been regarded as model electrocatalysts. Optimization of the electrocatalytic activity of MOFs is challenging, and an effective strategy for this optimization is the construction of a well-defined interfacial bond bridge. In this work, an in situ approach of composite synthesis is reported for MOF (CoNiNH₂BDC) with MXenes (Mo₂Ti₂C₃), as the electrocatalytic properties of MOF can be greatly enhanced with the incorporation of the conductive material MXene. The prepared composite material was characterized thoroughly using XRD, XPS, FESEM, EDX, TEM, and BET. The synergistic effect of both components of this composite material resulted in enhanced conductivity and the number of active sites, which led to enhanced electrocatalytic performance. The CoNiNH₂BDC MOF with different ratios of Mo₂Ti₂C₃ MXene were synthesized, and the resulting materials were evaluated for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities. It was observed that the MOFMX3 attained a 10 mA cm⁻² current density at 1.44 V for OER and −0.037 V for HER (vs. RHE), and lower values of Tafel slopes of 44.8 mV dec⁻¹ for OER and 45 mV dec⁻¹ for HER in 0.1 M KOH were achieved. The higher double layer capacitance (C_dl) values lead to high electrochemical surface area (ECSA) values. Lower Tafel slope values for MOFMX3 show that the presence of MXene nanosheets in the hybrid provides support to the layered and porous configuration of MOF, and the chances of the interaction of electrolyte to the catalytically active sites are significantly enhanced. This work highlights the idea of growing bimetallic MOFs on Mo₂Ti₂C₃ MXene using an interdiffusion reaction strategy and opens up an avenue for designing highly electrocatalytic systems.