Exposed facet-controlled N2 electroreduction on distinct Pt3Fe nanostructures of nanocubes, nanorods and nanowires

Understanding the correlation between exposed surfaces and performances of controlled nano catalysts can aid effective strategies to enhance electrocatalysis, but this is as yet unexplored for the nitrogen reduction reaction (NRR). Here, we first report controlled synthesis of well-defined Pt3Fe nanocrystals with tunable morphologies (nanocube, nanorod and nanowire) as ideal model electrocatalysts for investigating the NRR on different exposed facets. The detailed electro catalytic studies reveal that the Pt3Fe nano crystals exhibit shape-dependent NRR electrocatalysis. The optimized Pt3Fe nanowires bounded with high-index facets exhibit excellent selectivity (no N2H4 is detected), high activity with NH3 yield of 18.3 mu gh(-)(1) mg(-1) cat (0.52 mu gh(-)(1) cm(ECSA)(-)(2); ECSA: electrochemical active surface area) and Faraday efficiency of 7.3% at -0.05 V versus reversible hydrogen electrode, outperforming the {200} facet-enclosed Pt3Fe nanocubes and {111} facet-enclosed Pt3Fe nanorods. They also show good stability with negligible activity change after five cycles. Density functional theory calculations reveal that, with high-indexed facet engineering, the Fe-3d band is an efficient d-d coupling correlation center for boosting the Pt 5d-electronic exchange and transfer activities towards the NRR.

Automated summary

This study reports the controlled synthesis of Pt3Fe nanocrystals as model electrocatalysts for NRR, showing shape-dependent electrocatalysis on different exposed facets. The optimized Pt3Fe nanowires with high-indexed facets exhibit excellent selectivity, high activity, and good stability in NRR, outperforming nanocubes and nanorods. Density functional theory calculations suggest that high-indexed facet engineering enhances Pt-Fe electronic exchange and transfer activities for NRR.