Probing the activity origin of the enhanced methanol electrooxidation on Ni-induced PdNix(OH)y-TaN/C catalyst with nitrogen vacancies

Abstract

Engineering high-performance inexpensive TaN-modified Pd-based nanostructures for alkaline methanol oxidation reaction(MOR) has attracted extensive attention, yet the related enhancement mechanism of TaN for MOR remains lacked. The core-shell like Pd3Ni1-TaN/C catalyst decorated with Ni(OH)2/NiOOH that contains highly dispersed Ni sites and nitrogen defects has been fabricated for the first time. The unsaturated coordination environment and core-shell like morphology of Pd3Ni1-TaN/C bring fruitful active sites and a down-shifted d-band center, making it a highly-efficient electrocatalyst for alkaline MOR (17.3-fold that of commercial Pd/C). Besides the electronic effects and surface defect sites of Pd3Ni1-TaN/C, TaN also helps MOR proceed via HCOOad pathway (non-CO) accompanied by enhanced OH adsorption induced by the addition of Ni. DFT(Density Functional Theory) calculations also further confirm the energy barrier of the formation of HCOOad intermediate and desorption energy of CO on Pd3Ni1-TaN/C are reduced. The introduction of Ni species and nitrogen vacancies enhances the CO tolerance evidently.