Electrocatalytic nitrogen reduction reaction (NRR) is a promising alternative to the traditional Haber-Bosch process. However, the sluggish kinetics and competitive hydrogen evolution reaction result in poor NH 3 yield and low Faradaic efficiency (FE). Herein, single bismuth atoms incorporated hollow titanium nitride nanorods encapsulated in nitrogen-doped carbon layer (NC) supported on carbon cloth (NC/Bi SAs/TiN/CC) is constructed for electrocatalytic NRR. Impressively, as an integrated electrode, it exhibits a superior ammonia yield rate of 76.15 μg mg cat −1 h −1 (9859 μg 𝝁mol Bi −1 h −1 ) at −0.8 V versus RHE and a high FE of 24.60% at −0.5 V versus RHE in 0.1 m Na 2 SO 4 solution, which can retain stable performance in 10 h continuous operation, surpassing the overwhelming majority of reported Bi-based NRR catalysts. Coupling various characterizations with theory calculations, it is disclosed that the unique monolithic core-shell configuration with porous structure endows abundant accessible active sites, outstanding charge-transfer property, and good stability, while the cooperation effect of Bi SAs and TiN can simultaneously promote the hydrogenation of N 2 into NH 3 * on the TiN surface and the desorption of NH 3 * to release NH 3 on the Bi SA sites. These features result in the significant promotion of NRR performance.

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Transition metal nitrides (TMNs) have received special concern as important energy storage materials, owing to their high conductibility, good mechanical strength, and superior corrosion resistance. However, their insufficient capacitance and poor cycling stability limit their practical applications for supercapacitors. Here, a novel three-dimensional (3D) self-supported integrated electrode consisted of porous nanowall arrays of ultrafine cobalt nitride (Co4N) nanoparticles encapsulated in a lanthanum oxycyanamide (LOC) matrix on carbon cloth (Co4N@LOC/CC) for outstanding electrochemical energy storage is rationally designed and fabricated. The 3D monolithic configuration of porous nanowall arrays facilitates the mass/charge transfer, the exposure of electroactive sites, and the enhancement of electrical conductivity. Meanwhile, the unique core–shell structure of Co4N@LOC can prevent ultrafine Co4N nanoparticles from sintering, agglomeration, and oxidation and promotes electron transfer dynamics during the redox reaction, meanwhile enhancing the stability of the electrode. Additionally, the synergy of Co4N and LOC can result in an efficient electron/ion transport in the process of the charge–discharge. Because of these features, the Co4N@LOC/CC electrode displays superior specific capacitance (895.6 mF cm–2 or 613.4 F g–1 at 1 mA cm–2) and admirable cycling durability (87.9% capacitance reservation after 10 000 cycles), surpassing the majority of nitride-based electrodes reported thus far. Furthermore, after being assembled into an asymmetric supercapacitor using active carbon (AC) as an anode, the obtained Co4N@LOC/CC//AC/CC device displays a high energy density of 41.7 Wh kg–1 at the power density of 875.8 W kg–1 with a high capacitance reservation of 87.6% after 5000 cycles at 2 mA cm–2. This work offers an efficient approach of combining TMNs with rare earth compounds to enhance the capacitance and stability of TMNs for supercapacitor electrodes.