Rock-Like MIL-53(Fe) Grown on Conductive CoNiTe2 Nanosheets for the Construction of a High-Efficiency OER Composite Electrocatalyst

The pursuit of high-efficiency, cheap, and durable electrocatalysts to generate a green and renewable hydrogen energy source is of exceeding interest, but it remains a considerably challenging task because of the slow oxygen evolution reaction (OER) and high overpotential. Herein, an interesting type of heterostructural composite MIL-53(Fe)/CoNiTe2/NF was constructed by the integration of rocky MIL-53(Fe) with conductive CoNiTe2 nanosheets well-distributed on nickel foam (NF). The heterostructural composite not only exhibits high electrocatalytic OER activity with a relatively low potential at 10 (190 mV) and 100 (225 mV) mA·cm–2 in alkaline media, as well as ultralow Tafel slope of only 24.4 mV·dec–1, which not only far outperforms the benchmark RuO2 catalyst but also shows the excellent stability over 50 h at a high current density of 100 mA·cm–2 with no evident decay. The improved performance of MIL-53(Fe)/CoNiTe2/NF could result from the synergistic interaction between MIL-53(Fe) and CoNiTe2, which enhances electrical conductivity, offers a large electroactive area, and exposes abundant electroactive sites. Density functional theory (DFT) calculations also reveal that the coupling of MIL-53(Fe) with CoNiTe2 facilitates charge redistribution, optimizes the adsorption energy of the OER intermediates, and lowers the reaction energy barrier. Moreover, the heterostructural composite as the anode is applied for the fabrication of a Pt/C/NF||MIL-53(Fe)/CoNiTe2/NF electrolytic cell, and its cell voltage is only 1.51 V at 10 mA·cm–2, which is significantly better than that of the standard cell Pt–C/NF||RuO2/NF (1.61 V). This result suggests that the combination of MIL-53(Fe) with bimetallic telluride offers an effective strategy for developing low-cost OER electrocatalysts with high efficiency for renewable energy conversion.