Breaking linear scaling relations by strain engineering on MXene for boosting N 2 electroreduction.

The development of N ₂ reduction reaction (NRR) electrocatalysts with excellent activity and selectivity is of great significance, but adsorption-energy linear scaling relations between reaction intermediates severely hamper the realization of this aspiration. Here, we propose an elegant strain engineering strategy to break the linear relations in NRR to promote catalytic activity and selectivity. Our results show that the N-N bond lengths of adsorbed N ₂ with side-on and end-on configurations exhibit opposite variations under strains, which is illuminated by establishing two different N ₂ activation mechanisms of "P-P" (Pull-Pull) and "E-E" (Electron-Electron). Then, we highlight that strain engineering can break the linear scaling relations in NRR, selectively optimizing the adsorption of key NH ₂ NH ₂ ** and NH ₂ * intermediates to realize a lower limiting potential (U _L ). Particularly, the catalytic activity-selectivity trade-off of NRR on MXene can be circumvented, resulting in a low U _L of -0.25 V and high Faraday efficiency (FE), which is further elucidated to originate from the strain-modulated electronic structures. Last but not least, the catalytic sustainability of MXene under strain has been guaranteed. This work not only provides fundamental insights into the strain effect on catalysis but also pioneers a new avenue toward the rational design of superior NRR catalysts.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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