Improving the electrocatalytic performance of Pd for formic acid electrooxidation by introducing tourmaline

Abstract

Palladium is the most effective catalyst with high initial activity for formic acid electrooxidation (FAEO) in direct formic acid fuel cells (DFAFCs), but the low performance of DFAFC comparing to H2-PEMFC and the accumulation of COad poisoning species on palladium restrict the commercialization of DFAFC. Herein, a novel and efficient FAEO catalyst, tourmaline modified Pd (Pd/TNP@SC) are prepared. A class of core@shell structured carbon coated tourmaline (TNP@SC) are equipped as the catalyst support to efficiently utilize the spontaneous polarization-induced electric field and far-infrared radiation of tourmaline for FAEO reaction. Physical and electrochemical measurements suggest that the existence of electric field and far-infrared radiation of tourmaline promote synthesizing smaller Pd nanoparticles, weakening the Pd-O bond, increasing molecular vibration and migration rate, and dissociating water molecules into OHad to spontaneously convert COad into CO2. Even under potentials applied higher than 0.3 V (vs. Ag/AgCl), Pd/TNP@SC catalysts still have high FAEO activity. Among all the Pd/TNP@SC catalysts investigated in this study, Pd/TNP@SC-800 owns the strongest electric field and far-infrared radiation, exhibits the best activity for FAEO, which is 3.1 times higher than that of tourmaline-free catalyst (Pd/SC)), and excellent CO-tolerance during FAEO reaction. This work provides an effective catalyst design strategy for FAEO.