Ammonia is one of the most important feedstocks for the production of fertilizer and as a potential energy carrier. Nitride compounds such as LaN have recently attracted considerable attention due to their nitrogen vacancy sites that can activate N 2 for ammonia synthesis. Here, we propose a general rule for the design of nitride-based catalysts for ammonia synthesis, in which the nitrogen vacancy formation energy (E NV ) dominates the catalytic performance. The relatively low E NV (ca. 1.3 eV) of CeN means it can serve as an efficient and stable catalyst upon Ni loading. The catalytic activity of Ni/CeN reached 6.5 mmol•g −1 •h −1 with an effluent NH 3 concentration (E NH3 ) of 0.45 vol %, reaching the thermodynamic equilibrium (E NH3 = 0.45 vol %) at 400 °C and 0.1 MPa, thereby circumventing the bottleneck for N 2 activation on Ni metal with an extremely weak nitrogen binding energy. The activity far exceeds those for other Co-and Ni-based catalysts, and is even comparable to those for Ru-based catalysts. It was determined that CeN itself can produce ammonia without Ni-loading at almost the same activation energy. Kinetic analysis and isotope experiments combined with density functional theory (DFT) calculations indicate that the nitrogen vacancies in CeN can activate both N 2 and H 2 during the reaction, which accounts for the much higher catalytic performance than other reported nonloaded catalysts for ammonia synthesis.

Effective integration of one-dimensional carbon nanofibers (CNF) and two-dimensional carbon sheets into three-dimensional (3D) conductive frameworks is essential for their practical applications as electrode materials. Herein, a novel "vein-leaf"-type 3D complex of carbon nanofibers with nitrogen-doped graphene (NG) was prepared through a simple thermal condensation of urea and bacterial cellulose. During the formation of the 3D complex CNF@NG, the graphene species was tethered to CNF via carbon-carbon bonds. Such an interconnected 3D network facilitates both the electron transfer and mass diffusion for electrochemical reactions.

Single-atom catalysts (SACs) have attracted significant attention because they exhibit unique catalytic performance due to their ideal structure. However, maintaining atomically dispersed metal under high temperature, while achieving high catalytic activity remains a formidable challenge. In this work, we stabilize single platinum atoms within sub-nanometer surface cavities in well-defined 12CaO•7Al 2 O 3 (C12A7) crystals through theoretical prediction and experimental process. This approach utilizes the interaction of isolated metal anions with the positively charged surface cavities of C12A7, which allows for severe reduction conditions up to 600°C. The resulting catalyst is stable and highly active toward the selective hydrogenation of nitroarenes with a much higher turnover frequency (up to 25772 h −1) than wellstudied Pt-based catalysts. The high activity and selectivity result from the formation of stable trapped single Pt atoms, which leads to heterolytic cleavage of hydrogen molecules in a reaction that involves the nitro group being selectively adsorbed on C12A7 surface.

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