This work reports a facile approach to monodisperse bismuth nanospheres (Bi-NPs), which are then evenly assembled on graphene oxide (GO) via a solution-based sonication method. The resultant Bi-NPs@GO composite can serve as a robust direct plasmonic photocatalyst to remove 42.3% of ppb-level NO from a continuous flow under UV illumination. Localized surface plasmon resonance (LSPR) of Bi nanospheres were confirmed by a numerical simulations and the intense LSPR on Bi nanospheres under UV illumination accounts for the generation of energetic hot electron/hole pairs for NO removal. Experimental results combined with the density functional theory calculation analysis indicate that the abundant carboxyl groups on GO play crucial roles in whole photocatalysis: (i) form a directional carrier deliver channel: Bi → C_graphene → C_COOH → O_COOH, facilitating the hot electrons transfer from the plasmonic Bi nanospheres to carboxyl groups and encouraging the carrier separation efficiency, (ii) enrich the reactant concentrations (O₂ and NO) around catalyst surface by adsorption, promoting the generation of active radicals O₂⁻ and the sequent oxidation of NO. Further examination of the photocatalytic NO oxidation by in situ DRIFT confirms the key roles of carboxyl groups as adsorption/reaction centers for photocatalytic NO oxidation, as well as the pathway of NO oxidation to nontoxic nitrate on the catalyst.

中文翻译：

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氧化石墨烯上组装的铋球：定向电荷转移增强了等离子光催化和原位DRIFTS研究

这项工作报告了一种简便的方法，用于单分散铋纳米球（Bi-NPs），然后通过基于溶液的超声处理方法将其均匀地组装在氧化石墨烯（GO）上。所得的Bi-NPs @ GO复合材料可以用作坚固的直接等离激元光催化剂，以在紫外线照射下从连续流中去除42.3％的ppb级NO。通过数值模拟证实了Bi纳米球的局部表面等离振子共振（LSPR），并且在UV照明下Bi纳米球上的强LSPR导致了用于去除NO的高能热电子/空穴对的产生。实验结果与密度泛函理论计算分析相结合表明，GO上丰富的羧基在整个光催化中起着关键作用：（i）形成定向载流子传递通道：Bi→C_石墨烯 →C _COOH  →O _COOH，促进热电子从等离激元Bi纳米球转移到羧基并提高载流子分离效率，（ii）通过吸附富集催化剂表面附近的反应物浓度（O ₂和NO），促进生成活性自由基Ò ₂ ^-和NO的相继式氧化。原位DRIFT对光催化NO氧化的进一步检查证实了羧基作为光催化NO氧化的吸附/反应中心的关键作用，以及NO氧化为催化剂上无毒硝酸盐的途径。