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  1. CO 2 electroreduction is developing as a promising technology to solve environmental and energy problems. Alloy catalysts with dissimilar local metal atoms induce geometric and electronic effects that may greatly contribute to their performance. However, the fundamental mechanisms for CO 2 reduction on a bimetallic Au alloy surface are still ambiguous. Here, we report effective CO 2 reduction by the synergies between electronic and geometric effects of Mo-doped Au nanoparticles (MDA NPs). A 97.5% CO faradaic efficiency and 75-fold higher current density than pure Au nanoparticles were achieved at −0.4 V versus the reversible hydrogen electrode for MDA NPs with at least 50 h lifetime. Our experimental and theoretical calculation results reveal that the Au surface with increased electron density from Mo can effectively enhance CO 2 activation. Moreover, the intermediate *COOH may be further stabilized by the local Mo atom through additional Mo–O binding to decrease the energy barrier. 
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  2. Abstract

    The interconnect half‐pitch size will reach ≈20 nm in the coming sub‐5 nm technology node. Meanwhile, the TaN/Ta (barrier/liner) bilayer stack has to be >4 nm to ensure acceptable liner and diffusion barrier properties. Since TaN/Ta occupy a significant portion of the interconnect cross‐section and they are much more resistive than Cu, the effective conductance of an ultrascaled interconnect will be compromised by the thick bilayer. Therefore, 2D layered materials have been explored as diffusion barrier alternatives. However, many of the proposed 2D barriers are prepared at too high temperatures to be compatible with the back‐end‐of‐line (BEOL) technology. In addition, as important as the diffusion barrier properties, the liner properties of 2D materials must be evaluated, which has not yet been pursued. Here, a 2D layered tantalum sulfide (TaSx) with ≈1.5 nm thickness is developed to replace the conventional TaN/Ta bilayer. The TaSxultrathin film is industry‐friendly, BEOL‐compatible, and can be directly prepared on dielectrics. The results show superior barrier/liner properties of TaSxcompared to the TaN/Ta bilayer. This single‐stack material, serving as both a liner and a barrier, will enable continued scaling of interconnects beyond 5 nm node.

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