Activated Ni-based metal-organic framework catalyst with well-defined structure for electrosynthesis of hydrogen peroxide

Catalyst with well-defined active sites and highly ordered mesoporous structure is of significant importance for electrocatalytic synthesis of hydrogen peroxide (H2O2) by a two-electron oxygen reduction reaction (ORR). Herein, we present a Ni-based MOF two-electron ORR electrocatalyst derived from zeolitic imidazolate framework-8 (ZIF-8) for H2O2 production. The partial substitution of Zn in ZIF-8 with Ni (MOF Ni-250) affords a favorable two-electron ORR catalytic performance, where the elemental Ni serves as an excellent active site. In addition, the catalytic performance of the catalyst is further enhanced by calcination treatment of MOF Ni-250 under 300 degrees C (c-MOF Ni-250), which removes the crystal water and other small molecules within MOF, thus exposing the active sites and transfer channel of reaction species in catalyst layer without structure destruction. The optimized c-MOF Ni-250 exhibits an excellent H2O2 selectivity of 95% and a high H2O2 production rate of 0.51 mol center dot gcat.(-1 center dot)h(-1) at 0.37 V (vs. RHE) in 0.1 M KOH. The acitve sites of Ni atom is futher confirmed by using density functional theory (DFT) calculations. This finding demonstrates that the as-developed catalyst has a great potential in electrocatalytic synthesis of H2O2 in practical applications.

Automated summary

A Ni-based MOF catalyst derived from modified ZIF-8 was developed for the synthesis of H2O2. The catalyst exhibited well-defined active sites and highly ordered mesoporous structure, and its catalytic performance was further enhanced by calcination treatment. The optimized catalyst showed excellent selectivity and high production rate in alkaline medium.