We elucidated the cooperative active sites of Ni–Pt alloy nanoparticles composed of Pt atoms isolated by Ni atoms and their neighboring Ni atoms for the efficient and selective hydrogenation of CO₂ toward CH₄. The stepwise methanation dynamics were revealed by in situ observations and transient changes in the infrared spectra during the hydrogenation of CO₂. It was found that the hydrogenation of CO species attached to the isolated Pt atoms proceeded through a bridging CO species between isolated Pt atoms and their neighboring Ni atoms, leading to an excellent selectivity toward CH₄. Kinetic studies revealed that the high H₂ dissociation ability of the Pt species accelerated the hydrogenation of the carbon species over the surface of the Ni–Pt alloy, thereby avoiding the rate limitations of CH₄ formation which are common for Ni catalysts. The bifunctional role of the isolated Pt atoms therefore allowed the efficient formation of CH₄ while maintaining the excellent selectivity of the Ni catalyst toward CH₄, despite Pt catalysts tending to favor CO production.

中文翻译：

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具有分离的Pt原子的Ni-Pt合金纳米颗粒及其相邻的Ni原子，用于CO ₂选择性加氢向CH _4的选择性加氢：原位和瞬态傅立叶变换红外研究

我们阐明了由Ni原子及其附近的Ni原子隔离的Pt原子组成的Ni-Pt合金纳米颗粒的协同活性位点，以有效和选择性地将CO ₂加氢成CH ₄。通过现场观察和CO ₂加氢过程中红外光谱的瞬态变化揭示了甲烷化的逐步动力学。发现附着于分离的Pt原子的CO物种的氢化通过分离的Pt原子与其相邻的Ni原子之间的桥连CO物种进行，从而导致对CH ₄的优异的选择性。动力学研究表明，高H ₂Pt物种的解离能力加速了Ni-Pt合金表面碳物种的氢化，从而避免了Ni催化剂常见的CH ₄形成速率限制。因此，尽管Pt催化剂倾向于有利于CO的产生，但是分离的Pt原子的双功能作用允许有效地形成CH _4，同时保持Ni催化剂对CH ₄的优异选择性。