Developing electrocatalysts that exhibit both high activity and ammonia selectivity for nitrate reduction is a significant and demanding challenge, primarily due to the complex nature of the multiple-electron reduction process involved. An encouraging approach involves coupling highly active precious metals with transition metals to enhance catalytic performance through synergy. Here, we report a ruthenium-nickel alloy catalyst with nanosheets (Ru-Ni NSs) structure that achieves a remarkable ammonia Faradaic efficiency of approximately 95.93%, alongside a yield rate of up to 6.11 g·h −1 ·cm −2 . Moreover, the prepared Ru-Ni NSs exhibit exceptional stability during continuous nitrate reduction in a flow reactor for 100 h, maintaining a Faradaic efficiency of approximately 90% and an ammonia yield of 37.4 mg·L −1 ·h −1 using 0.05 M nitrate alkaline electrolyte. Mechanistic studies reveal that the catalytic process follows a two-step pathway, in which HONO serves as a migration intermediate. The presence of a partially oxidized Ru (002) surface enhances the adsorption of nitrate and facilitates the release of the migration intermediate by adjusting the strength of the electrostatic and covalent interactions between the adsorbate and the surface, respectively. On the other hand, the Ni (111) surface promotes the utilization of the migration intermediate and requires less energy for NH 3 desorption. This tandem process contributes to a high catalytic activity of Ru-Ni NSs towards nitrate reduction.
Jiafu Li,Yanran Feng,Xingyun Li,Tianjun Zhang,Xia Liu,Ning Wang,Qiming Sun
Ultrafine metal alloy nanoparticles are emerging as highly effective catalysts for the generation of hydrogen from ammonia borane (AB) hydrolysis. The fabrication of multimetallic alloys with high activity, stability, and metal utilization remains the biggest challenge. Herein, sub-2 nm ternary Rh–Ru–Ni alloys were encapsulated within the interlayers of layer-stripped montmorillonite (MMT) via a simple impregnation method. Experiment and theory results revealed that the synergistic effect of the trimetallic alloy significantly lowers the energy barrier for the AB hydrolysis reaction, by boosting the adsorption and O–H dissociation of H2O molecules. The optimized Rh0.8Ru0.2Ni0.25@MMT-S catalyst achieves high turnover frequency values of 2961 and 784 min–1 at 298 and 273 K, respectively, as well as high recycling stability and thermal resistance. Moreover, the encapsulation method has versatility and can be also applied to synthesize ultrafine Pt- and Ir-based nanoparticles. This study not only highlights the role of the synergistic effect in trimetallic alloys for improving hydrogen evolution but also offers a route to design highly efficient and stable metal nanocatalysts for other applications.
Graphical Monohydric alcohols are a potential fuel, and herein, monohydric alcohols have been selectively synthesized from multicarbon sugars by modulating the electron distribution of Ru and enhancing the hydrodeoxygenation process of biomass. Ru-based catalysts are widely used in catalytic reactions, but the electron-deficient nature promotes strong decarbonylation, leading to complete deoxygenation during the conversion of polyhydroxy biomass. Despite extensive research, effectively suppressing this decarbonylation activity remains challenging. Herein, electron-rich Ru and electron-deficient Ni formed due to the electron migration of Ni → Ru have a synergistic catalytic effect, controlling the precise cleavage of C N bonds by Ru 0 and retaining most of the C O bonds. The amorphous Al 2 O 3 is sufficiently bound to the substrate to promote rapid hydrogenation. This modification effectively suppresses the intrinsic decarbonylation activity of Ru and improves selectivity for hydrodeoxygenation. Using carbohydrates as substrates, the Ru–Ni bimetallic catalysts preferentially promote the hydrodeoxygenation pathway, resulting in a significant increase in C3+ monohydric alcohol yields. This work presents a new strategy for modulating reaction pathways via electronic structure engineering, offering valuable insights into the potential of Ru–Ni systems for biomass conversion and sustainable alcohol synthesis.
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