2D Al-MOF with ultrathin nanoflake-assembled hollow microstructures for electrochemical hydrogen peroxide production

Electrochemical transformation from oxygen reduction reaction (ORR) to hydrogen peroxide (H₂O₂) is one of the promising green techniques to synthesis H₂O₂. However, due to the competing two processes of 2e⁻ and 4e⁻ORR with different products, designing and synthesizing highly selective and active 2e⁻ ORR electrocatalysts for H₂O₂ production is fundamentally and practically important. In this work, we used a simple solvothermal method and self-template strategy to create ultrathin 2D Al-MOF nanosheets for efficient electrocatalytic synthesis of H₂O₂ by 2e⁻ ORR. The presence of a mixed solvent and sulfate ion is critical to the formation of the specific structure. Naturally, their ultrathin morphology and abundant mesoporous formation leads to the sufficient exposure of electrochemically active sites and high mass/electron transfer capability. Therefore, the Al-MOF NSs show excellent electrocatalytic performance for 2e⁻ ORR. The optimized Al-MOF NSs-1 exhibited the best ORR catalytic performance with almost no overpotential and high selectivity for 2e⁻ ORR to H₂O₂ (94 %–98 %) in a wide range of low potentials in alkaline electrolyte. Meanwhile, the high reaction rate of 2.56 molg_cat⁻¹h⁻¹ for H₂O₂ production has also been achieved at 0.6 V. Furthermore, the Al-MOF NSs-1 enable to catalyze H₂O₂ production with excellent durability and selectivity after long-term stability test (10,000 cycles) and 11 h of potentiostatic electrolysis. The present study indicates the promising application of metal organic frameworks (MOFs) materials in H₂O₂ electrochemical synthesis.