Machine learning-based screening of nitrogen-doped graphene NRR diatomic catalysts

This research seeks to investigate extremely efficient catalysts for the nitrogen reduction process (NRR), utilizing machine learning (ML)-aided density functional theory (DFT) computations. Specifically, we investigate dual transition metal atoms anchored on hexagonal nitrogen-doped graphene (TM1-TM2@N6G) as prospective high-activity catalysts for the NRR. The findings indicate that the synergistic effect of dual transition metal atoms in the TM1-TM2@N6G catalyst overcomes the intrinsic constraints of the linear relationship among intermediates, facilitating the activation and adsorption of N2, thereby exhibiting significant potential for ammonia synthesis through N2 reduction. Particularly, four catalysts screened by ML and DFT exhibit good stability and excellent selectivity and activation towards N2. Among them, the catalysts Ti-Cr@N6G, Ti-Mo@N6G, and Ti-Pd@N6G possess two reaction pathways with minimum reaction energies of 0.55 eV, 0.50 eV, and 0.40 eV, respectively. Remarkably, Ti-Co@N6G, which features a single reaction pathway, exhibits a reaction energy lower than 0.05 eV, allowing the NRR to proceed spontaneously. It is noteworthy that incorporating ML into DFT calculations facilitates the rapid screening of all transition metal combinations, significantly accelerating the research on catalytic performance and optimizing the selection of catalysts.