Synergistic effect of trimetallic doping and π-π conjugation in NiZnCo-ZIF@HHTP for efficient oxygen evolution reaction

Abstract

Zeolite imidazole frameworks (ZIFs) structures are widely used as an efficient catalyst for metal organic frameworks (MOFs) in electrocatalysis. In this work, the structure of the trimetallic ZIFs sample was rationally designed by the method of doping with Ni2+ and Zn2+. After that, a layer of highly conductive π-π conjugated organic molecules was wrapped on the trimetallic ZIFs sample to form a heterojunction structure of NiZnCo-ZIF@HHTP composite. The activity of oxygen evolution reaction (OER) of NiZnCo-ZIF was improved after it was combined with HHTP. NiZnCo-ZIF@HHTP presents a low overpotential (η ≈ 193 mV @10 mA cm−2), a small Tafel slope (97.4 mV dec−1) and outstanding stability for OER in 1 M KOH solution. The superior OER performance of NiZnCo-ZIF@HHTP is due to the effect of doping of Ni and Zn to form a trimetallic ZIF material. The synergistic effect of Ni Zn codoped enhances the conductivity of ZIF-67 material. Meanwhile, the π-π conjugation effect of HHTP organic macromolecule can further enhance the electrical conductivity of NiZnCo-ZIF. The result suggests that the co-doping of polymetallic cations and the coating of conducting organic molecules can be vital for modifying ZIFs electrocatalysts. This work provides a meaningful reference value for modifying non-precious metal ZIFs materials in electrocatalysis.