Ultrasmall FeMoNi Tri-Metal nanoparticles confined by tannic acid-derived carbon as bi-functional electrocatalyst for oxygen evolution and urea oxidation

Abstract

Exploration of the electrocatalysts with uniformly dispersed metal nanoparticles (NPs) is important to achieve high electrocatalytic activity, but the NPs always trend to aggregate during fabrication or application. Herein, ultrasmall FeMoNi tri-metal NPs was confined by tannic acid-derived carbon layer and utilized as bi-functional electrocatalyst. The interconnected nanosheets network with open porous structure and electrolyte/gas diffusion channels can reduce the mass transfer resistance. The tri-metal NPs with average diameter of only 11.9 nm are uniformly distributed between the space limited carbon interlayer to avoid aggregation and provide enhanced electric conductivity. Meanwhile, the physical carbon armor and electron tunneling effect can enhance the alkali resistance and electrocatalytic activity/stability of the electrocatalyst. Therefore, the optimized C@FeMoNi/CC electrode can achieve overpotential of 244 mV and potential of 1.4 V at 10 mA cm−2 for OER and UOR, respectively, and high long-term cyclic stability for 40 h. Moreover, the high-valence NiFe species are considered as the highly active centers. This plant polyphenol derived surface coating and carbonization strategy with controllable functional building blocks provides a solution for the rational design of energy conversion devices.