Low-cost and efficient electrocatalysts are urgently required for the N 2 reduction reaction (NRR) to produce NH 3 under ambient conditions. By using first-principles calculation, we systematically investigated the NRR catalytic activity of the transition metal (TM, including Mn, Fe, Co, and Ni) monomer-, dimer-, and trimer-anchored graphdiyne (GDY) monolayers. It is shown that most of the TM monomer-and dimer-anchored GDY monolayers have enhanced NRR catalytic activity compared with the Ru(0001) stepped surface. Especially, the Co dimer-anchored GDY monolayer (Co 2 @GDY) exhibits the best NRR catalytic activity with the onset potential of −0.43 V and a high ability to suppress the competing hydrogen evolution reaction. The high NRR catalytic activity of Co 2 @GDY could be attributed to the localized electronic states near the Fermi level and the strong electron-donating ability of the GDY monolayer. Furthermore, an approximate linear trend between the predicted onset potential and the N adsorption energy is revealed, which may act as a simple descriptor for the intrinsic NRR catalytic activity of such catalysts. Our findings not only propose an efficient and low-cost double-atom catalyst for NRR but also provide a new clue for designing TM atomic catalysts based on GDY sheets for various electrocatalysis applications.

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Using the adiabatic trajectory method, the migration energy barriers for the migration of Li ions and Cr ions along the one-dimensional diffusion pathway in pure and Cr doped LiFePO4 are obtained from first principles calculations. The results show that while Li ions can diffuse along the diffusion pathway easily, Cr ions do not easily diffuse away from their initial positions. This means that the heavy Cr ions will block the one-dimensional diffusion pathway of the material. Monte Carlo simulations are performed to evaluate the influences of the blocking behaviours on the electrochemical performance of LiFePO4 cathode material for Li ion secondary batteries. The results show that the evaluated capacity is highly sensitive to the amount of the dopant, the size of the super-cell being used for simulation (particle size of the powder cathode material) and the Monte Carlo steps for statistics (charge–discharge current density).

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