Introducing oxophilic metal and interstitial hydrogen into the Pd lattice to boost electrochemical performance for alkaline ethanol oxidation

Abstract

The sluggish kinetics of the ethanol oxidation reaction (EOR), poor C1 selectivity and susceptibility to toxicity of CO intermediates hinder the commercialization of direct ethanol fuel cells (DEFCs). In this paper, we reported an achievable method to fabricate an efficient catalyst of stable PdCoH nanosheets (NSs) for the EOR by introducing both the oxophilic metal cobalt and hydrogen atoms into the palladium lattice. Owing to the unique 2D curly sheet-structure of 2.3 nm thickness, the obtained catalyst exhibits a larger electrochemical active surface area. By comparison with PdCo NSs, PdH NSs, and commercial Pd/C counterparts, it was found that the obtained PdCoH NS catalyst exhibits the best electrocatalytic performance toward ethanol oxidation in alkaline solution, and its mass activity is higher than that of most of the Pd-based catalysts reported so far. The CO stripping and the in situ Fourier transform infrared (FTIR) spectroscopy study indicate that the incorporation of cobalt and hydrogen atoms is conducive to the improvement of anti-CO ability and the C1 pathway selectivity. Further investigation of the CV curves elucidates that the oxophilicity of Co in the PdCoH NSs is more favorable for the adsorption of OH⁻, which promotes the removal of CO_ads. In addition, the valence band spectra show the lowest d-band center of the PdCoH NSs in comparison with PdCo NSs, PdH NSs, and commercial Pd/C counterparts, which helps weaken the adsorption of CO, and thus enhances the CO tolerance and C1 selectivity. We believe that this work opens the door for rational design of noble metal alloy catalysts with excellent performance through combining the advantages of oxophilic metals and H atoms.