H-Implanted Pd Icosahedra for Oxygen Reduction Catalysis: From Calculation to Practice

Although palladium (Pd) has gradually emerged as the most likely candidate to replace platinum (Pt) in the oxygen reduction reaction (ORR), the specific electronic structure of conventional Pd results in too strong Pd-O binding strength and unsatisfactory ORR performance. Herein, guided by density functional theory, we have explored a strategy to expand lattice spacing by implanting hydrogen (H) atoms in Pd nanocrystals (NCs), which realizes decreased electron density to boost ORR. We found that all H-implanted Pd NCs show universally promoted ORR activities compared with their corresponding Pd NCs counterparts. Significantly, the H-implanted Pd icosahedra/C with twinned {111} facet not only exhibits the highest ORR activity among all studied catalysts, but also possesses good durability with limited changes after 30,000 cycles and excellent chemical stability with preservation up to 5 months. X-ray absorption of the fine structure demonstrates that enhanced ORR performances of H-implanted Pd NCs can be attributed to the reduced coordination number and valence band, as a result of the incorporation of H atoms. Furthermore, the twinned {111} facet in H-implanted Pd icosahedra is the critical factor in further minimizing the ORR barrier and stabilizing key reaction intermediates, resulting in the highest properties among all investigated catalysts. [GRAPHICS] .

Automated summary

Using density functional theory, a strategy to enhance oxygen reduction reaction (ORR) activity by implanting hydrogen atoms in Pd nanocrystals was explored, showing universally promoted ORR activities. Among all studied catalysts, H-implanted Pd icosahedra/C with twinned {111} facet exhibited the highest ORR activity and good durability, attributed to reduced coordination number and valence band, as well as the critical role of twinned {111} facet in minimizing the ORR barrier.