Constructing Built-In Electric Field in Co3znc-Co Mott-Schottky Heterojunction to Enhance Dual Active Sites of Catalyst as an Orr Catalyst for Microbial Fuel Cells

Abstract

In the field of oxygen electrocatalysis, interface engineering was regarded as a pivotal technique for developing cost-effective catalysts with well-defined structures and enhanced stability. Here, varying ratios of ZIF-8/67 were employed to obtain an N-doped C-coated Co3ZnC-Co heterojunction structure (Co3ZnC-Co@NC). The formation of heterojunctions facilitated the transfer of charge from Co nanoparticles to Co3ZnC, altering the surface structure to accelerate the cleavage of the O-O bond in the *OOH intermediate. The optimized Co3ZnC-Co@NC exhibited excellent ORR catalytic activity in PBS environments, with half-wave potentials of 0.763 V, surpassing the commercial Pt/C catalyst (0.686 V). Meanwhile, Co3ZnC-Co@NC illustrated excellent methanol tolerance and operational stability, with a mere 3 mV reduction observed after 5000 cyclic voltammetry (CV) cycles. It was noteworthy that the material exhibits high performance as an air cathode in microbial fuel cells (MFCs), displaying high power density (1.28 W m−2) and outstanding stability (60 days). This work presented novel insights into the preparation of durable ORR catalysts for AC-MFC applications.

Keywords: Oxygen reduction reaction, heterojunction, microbial fuel cell, d-band center, Neutral environment