N₂ electroreduction reaction (NRR) offers a feasible and promising alternative for NH₃ production by using clean energy sources. However, it is still obstructed by the pretty low NH₃ yield rate and Faradaic efficiency (FE) primarily due to the undesired competing hydrogen evolution reaction and the extremely stable N≡N bond. Herein, bismuth nanoparticles were successfully embedded in N and P co-doped carbon nanoflakes (Bi/NPC) by high-temperature pyrolyzation of Bi-zeolitic imidazole frameworks (ZIF) followed by phosphorization, and used as a high-efficiency catalyst toward N₂ electroreduction to NH₃. In 0.1 M KHCO₃ electrolyte, Bi/NPC exhibits excellent NRR performances, including a high NH₃ yield rate of 3.12 µg·h⁻¹·cm⁻² (−0.6 V vs. reversible hydrogen electrode (RHE)), an outstanding FE of 13.58% (−0.4 V vs. RHE), and a remarkable stability up to 36 h under ambient conditions. This outstanding NRR catalytic activity is mainly attributed to the intrinsic electrocatalytic NRR activity combined with the inert hydrogen evolution reaction (HER) activity of Bi, the adsorption and activation of N₂ facilitated by N dopants, as well as the superior conductivity and the large specific surface area of the two-dimensional layered carbon matrix. Notably, the hydrogen source provided by P dopant promotes the hydrogenation of the adsorbed N, which further boosts the NRR performance in alkaline electrolyte. The ultralong durability of Bi/NPC is attributed to the highly dispersed bismuth catalytic active centers confined in the skeleton of N and P co-doped carbon nanoflakes, which inhibits the agglomeration of bismuth centers. This work presents a novel avenue for designation and fabrication of high-performance Bi-based electrocatalysts for NRR.

Supported single-atom catalysts (SACs) possess high catalytic activity, selectivity, and atom utilizations. However, the atom coordination environments of SACs are difficult to accurately regulate due to the high complexity of coordination site and local environment of support. Herein, we develop an in-situ electrochemical cation-exchange method to fill the cation vacancies in MnO₂ with Ru single atoms (SAs). This obtained catalyst exhibits high mass activity, which is ~ 44 times higher than commercial RuO₂ catalyst and excellent stability, superior to the most state-of-the-art oxygen evolution reaction (OER) catalysts. The experimental and theoretical results confirm that the doped Ru can induce charge density redistribution, resulting in the optimized binding of oxygen species, and the strong covalent interaction between Ru and MnO₂ for resisting oxidation and corrosion. This work will provide a new concept in the synthesis of well-defined local environments of supported SAs.