Prussian blue analogues (PBAs) have shown to be useful as earth-abundant electrocatalysts for the Oxygen Evolution Reaction (OER) in acidic, neutral and alkaline media. Still, further improvements can be achieved by increasing their electrical conductivity. In this work, we have obtained and fully characterized a variety of monodisperse core@shell hybrid nanoparticles of Au@PBA (PBA of NiIIFeII and CoIIFeII) with different shell sizes. Their electrocatalytical activity is evaluated by studying the OER, which is compared to the pristine PBA and other Au-PBA heterostructures. It was observed that the introduction in a core@shell of 5-10 % of Au in weight leads to an increment in the electroactive mass able to be reduced or oxidized and thus, to a higher number of sites capable to take part in the OER. This larger amount of electroactive sites leads to a significant decrease in the onset potential (a reduction of the onset potential up to 100 mV and an increase up to 420 % of the current density recorded at an overpotential of 350 mV), while the Tafel slope remains unchanged, suggesting that Au reduces the limiting potential of the catalyst with no variation in the reaction kinetics. These effects are not experimented in the other Au-PBA nanostructures mainly due to the lower contact between both compounds and the oxidation of Au. Hence, an Au core activates the PBA shell and increases the conductivity of the resulting hybrid while the PBA shell prevents Au oxidation. These improvements come from the strong synergistic effect existing in the core@shell structure and evidence the importance of the chemical design for preparing PBA-based nanostructures displaying better electrocatalytic performances and higher electrochemical stabilities.

中文翻译：

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通过在核@壳异质结构中引入金纳米颗粒增强普鲁士蓝类似物的电催化活性和稳定性

普鲁士蓝类似物（PBA）已证明可用作酸性，中性和碱性介质中富氧反应（OER）的富含地球的电催化剂。另外，可以通过增加其电导率来实现进一步的改进。在这项工作中，我们获得并充分表征了具有不同壳尺寸的Au @ PBA（NiIIFeII和CoIIFeII的PBA）的各种单分散核@壳杂化纳米颗粒。通过研究OER评估了它们的电催化活性，将其与原始的PBA和其他Au-PBA杂结构进行了比较。观察到，在核壳中引入5-10重量％的Au重量导致电活性物质的增加，其能够被还原或氧化，并且因此导致更多的能够参与OER的位点。大量的电活性位点导致起始电势显着降低（起始电势降低至100 mV，并且在350 mV过电势下记录的电流密度增加至420％），而Tafel斜率保持不变，表明Au降低了催化剂的极限电势而反应动力学没有变化。这些效果未在其他Au-PBA纳米结构中进行实验，这主要是由于两种化合物之间的接触减少以及Au的氧化。因此，Au核激活了PBA壳并增加了所得杂化物的电导率，而PBA壳则阻止了Au的氧化。