Main‐group (s‐ and p‐block) metals are generally regarded as catalytically inactive due to the delocalized s/p‐band. Herein, we successfully synthesized a p‐block antimony single‐atom catalyst (Sb SAC) with the Sb−N4 configuration for efficient catalysis of the oxygen reduction reaction (ORR). The obtained Sb SAC exhibits superior ORR activity with a half‐wave potential of 0.86 V and excellent stability, which outperforms most transition‐metal (TM, d‐block) based SACs and commercial Pt/C. In addition, it presents an excellent power density of 184.6 mW cm−2 and a high specific capacity (803.5 mAh g−1) in Zn–air battery. Both experiment and theoretical calculation manifest that the active catalytic sites are positively charged Sb−N4 single‐metal sites, which have closed d shells. Density of states (DOS) results unveil the p orbital of the atomically dispersed Sb cation in Sb SAC can easily interact with O2‐p orbital to form hybrid states, facilitating the charge transfer and generating appropriate adsorption strength for oxygen intermediates, lowering the energy barrier and modulating the rate‐determining step. This work sheds light on the atomic‐level preparing p‐block Sb metal catalyst for highly active ORR, and further provides valuable guidelines for the rational design of other main‐group‐metal SACs.

Nickel hydroxide (Ni(OH)2) has been identified as one of the best promising electrocatalyst candidates for urea oxidation reaction (UOR) due to its flexible structures, wide compositions, and abundant 3d electrons under alkaline conditions. However, its layered structure with limited exposed edge sites severely hinders further improvement of the UOR activity. Herein, oxygen‐vacancy rich and vanadium doped Ni(OH)2 (Ovac‐V‐Ni(OH)2) catalysts are prepared and synergistically boost the urea electrooxidation. Vanadium doping contributes more exposed active sites, and simultaneously generates oxygen vacancies, switching the rate‐determining step of UOR from *COOH deprotonation to the N–H bond cleavage process and lowering the thermodynamic barrier by around 1.13 eV. The novel Ovac‐V‐Ni(OH)2 demonstrates good electrocatalytic performances with a working potential of 1.47 V at a high current density of 100 mA cm−2. Synergistic engineering of doping and oxygen vacancy is a promising strategy for designing efficient UOR electrocatalysts.

The urea oxidation reaction (UOR) is considered as an alternative to the oxygen evolution reaction for high-efficiency hydrogen production. However, an urea molecule is relatively complex, containing both electron-donating amino (−NH2) and electron-withdrawing carbonyl (CO) groups, and understanding the influence of different functional groups on the adsorption behavior is conducive to the rational design and preparation of high-performance UOR catalysts. Herein, we report a simple synthesis of the Ni3N/Mo2N heterostructure and a systematic investigation of urea-assisted electrolytic hydrogen production. Both temperature-programmed desorption and theoretical calculations decipher that −NH2 and CO groups of the urea molecule are more easily adsorbed on Ni3N and Mo2N, respectively. Meanwhile, the Ni3N/Mo2N heterostructure could combine and enhance the advantages of individual components, optimizing the adsorption of urea. Besides, this heterostructure is also beneficial to improving the hydrogen evolution reaction performance. As expected, in the two-electrode urea-assisted water electrolyzer utilizing Ni3N/Mo2N as bifunctional catalysts, hydrogen production can readily occur at an evidently lower voltage (1.36 V@10 mA cm–2), which is much lower than that of traditional water electrolysis, as well as 7 times higher hydrogen production rate is achieved.

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