2D iron/cobalt metal-organic frameworks with an extended ligand for efficient oxygen evolution reaction

The design of an efficient OER catalyst is significant for water splitting. Metal-organic frameworks (MOFs) are emerging as promising electrocatalysts due to their diversity of structure and tunability of function. In this paper, 2D FexCo1-x-MOF1/NF with an extended ligand (biphenyl-4,4 '-dicarboxylic acid, BPDC) is constructed on nickel foam by a solvothermal method. Compared with the MOF2 synthesized by using BDC (1,4-bezenedicarboxylate), MOF1 shows excellent performance. Among MOF1, Fe0.5Co0.5-MOF1/NF exhibits outstanding performance with a low overpotential (217 mV) and a small Tafel slope (31.16 mV Dec(-1)) at 10 mA cm(-2) and performs well at a high current density. In addition, the catalyst is remarkable in terms of durability both in alkaline solution and simulated seawater. The synergetic effect between Fe and Co and more active sites exposed play an important role in improving the OER activity. This work provides an effective strategy for the rational design of MOFs as inexpensive electrocatalysts.

Automated summary

The design of an efficient OER catalyst is crucial for water splitting. Metal-organic frameworks (MOFs) with their versatile structures and adjustable functions have emerged as promising electrocatalysts. In this study, 2D FexCo1-x-MOF1/NF with an extended ligand, BPDC, was fabricated on nickel foam using a solvothermal method. Compared to MOF2 synthesized with BDC, MOF1 exhibited excellent performance. Among MOF1, Fe0.5Co0.5-MOF1/NF showed outstanding activity with a low overpotential (217 mV) and a small Tafel slope (31.16 mV Dec(-1)) at 10 mA cm(-2), while maintaining good performance at high current densities. The catalyst also displayed remarkable durability in alkaline solution and simulated seawater. The synergetic effect between Fe and Co, as well as the increased number of active sites exposed, played a crucial role in enhancing the OER activity. This work provides an effective strategy for the rational design of inexpensive MOFs as electrocatalysts.