Two kinds of Ni(OH)₂ nanostructures, including thin nanosheets (NSs) with a thickness of 15–20 nm and very small nanoparticles (NPs) with a diameter of 2–3 nm, were immobilized on polypyrrole/graphene oxide (PPy/GO) via a facile strategy due to the coordination interaction between Ni²⁺ and −NH– segments in PPy chains. The obtained Ni(OH)₂/PPy/GO presented excellent electrocatalytic activity for the urea oxidation reaction (UOR) due to the excellent hierarchical nanostructures and the synergistic effects of lamellar GO, conductive PPy, and electrocatalytically active Ni(OH)₂. The electrocatalytic mechanism and the role of the each component in the Ni(OH)₂/PPy/GO to UOR were also investigated in detail. PPy/GO with good conductivity and large surface area can effectively facilitate the electronic transmission of UOR. Super smaller Ni(OH)₂ NPs are electrocatalytic active centers for UOR. Therefore, Ni(OH)₂/PPy/GO can serve as a kind of excellent electrocatalyst for UOR in alkaline medium and reveal potential applications to urea-rich wastewater disposal, hydrogen production, and direct urea fuel cells.

中文翻译：

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Ni（OH）₂ /聚吡咯/氧化石墨烯纳米片作为尿素氧化的优良电催化剂

两种Ni（OH）₂纳米结构，包括厚度为15–20 nm的薄纳米片（NSs）和直径为2-3 nm的非常小的纳米颗粒（NPs），被固定在聚吡咯/氧化石墨烯（PPy /由于PPy链中Ni ²⁺和-NH-链段之间的配位相互作用，通过一种简便的策略获得了GO）。由于优异的分级纳米结构以及层状GO，导电PPy和电催化活性Ni（OH）₂的协同作用，所得的Ni（OH）₂ / PPy / GO对尿素氧化反应（UOR）表现出优异的电催化活性。Ni（OH）₂的电催化机理及各组分的作用/ PPy / GO到UOR也进行了详细调查。具有良好导电性和大表面积的PPy / GO可以有效地促进UOR的电子传输。超小型Ni（OH）₂ NP是UOR的电催化活性中心。因此，Ni（OH）₂ / PPy / GO可以作为碱性介质中UOR的优良电催化剂，并在富尿素废水处理，制氢和直接尿素燃料电池中显示出潜在的应用。