A high-performance NiPMg ternary anode catalyst for direct borohydride fuel cells

Abstract

The direct borohydride fuel cell (DBFC) is an innovative energy conversion device, which is known for its high energy density and rapid startup capability. However, the design of high-performance and cost-efficient anode catalysts is still challenging. Herein, an amorphous NiPMg ternary catalyst has been successfully synthesized by simple constant potential electrodeposition and the structure, morphology and performance investigated systematically. Experimental and DFT theoretical calculation results indicate that when the appropriate amount of magnesium is introduced, the intrinsic activity of the prepared catalyst is enhanced significantly, the adsorption to reactants or intermediates clearly strengthened, the oxidation of nickel and the hydrogen evolution reaction (HER) inhibited effectively, and the reaction energy barrier of the rate-determining step (RDS) in the borohydride oxidation reaction (BOR) process is greatly reduced. As a result, the NiPMg catalyst exhibits great catalytic activity, selectivity and stability to the BOR. Moreover, the DBFC with the NiPMg catalyst anode can deliver a peak power density of 484 mW cm⁻² and an open-circuit voltage of 1.92 V at 343 K. At the same time, it can run stably at a current density of 50 mA cm⁻² for 40 h. Therefore, this research may provide a new design strategy for the development of cost-effective and efficient nonprecious metal anode catalysts for DBFCs.