Rational synthesis of MOF-Derived Cobalt-Based binary selenides nanocrystals for electrochemical oxygen evolution reaction

Water splitting is considered as one of the key reactions in energy conversion and storage. In this context, development of low-cost durable electrocatalysts for water splitting, in particular, oxygen evolution reaction (OER) is of utmost importance. Herein, we report the synthesis of Co-based selenides, i.e., Co-Se, NiCo-Se, FeCo-Se and MoCo-Se via the synthesis of hybrid MOF nanostructures, followed by hydrothermal process. Among them, CoMo-Se exhibited superior electrocatalytic activity towards OER in 1 M KOH solution compared to other catalyst and benchmark IrO₂. For example, it exhibited an overpotential (η₁₀) of 268 mV at a current density of 10 mA cm⁻², whereas the recorded values for CoFe-Se, CoNi-Se, Co-Se and IrO₂ were 312, 346, 374 and 311 mV, respectively at the same current density. In the same context, CoMo-Se revealed a Tafel slope of 55.6 mV decade⁻¹, while the calculated values for CoFe-Se, CoNi-Se, Co-Se and IrO₂ were 60.4, 97.9, 85.4 and 81.6 mV decade⁻¹, respectively. The superior catalytic performance of CoMo-Se was attributed to its unique porous architecture with high electrochemical active surface area (ECSA), enhanced electrical conductivity, high value of double layer capacitance (C_dl) and the high content of Co³⁺. This work provides a feasible route for designing MOF-derived bimetallic selenides for the energy conversion and storage applications.