Department of Chemical Engineering , Hanyang University , Ansan 15588 , Republic of Korea.
Department of Chemical Engineering , NED University of Engineering and Technology , Karachi 75270 , Pakistan.
ACS Appl Mater Interfaces. 2019 Oct 9;11(40):36960-36969. doi: 10.1021/acsami.9b12371. Epub 2019 Sep 30.
It is not facile to obtain ultrathin two-dimensional (2D) WO nanosheets through the exfoliation of their bulk counterpart in solution due to strong covalent interaction between interlayers. In addition, they require additional functionalization with cocatalysts to expand their applicability in photocatalytic organic reactions owing to their insufficient conduction band edge position. Here, we report a chemical approach for the simultaneous production and functionalization of ultrathin 2D WO nanosheets through the direct conversion of metallic WS nanosheets, accomplished by the spontaneous formation and deposition of PdO nanoclusters on the nanosheet surface in HO. When chemically exfoliated metallic WS nanosheets were simply mixed with KPdCl in HO under mild conditions (50 °C, 1 h), they were converted to semiconducting WO nanosheets on which PdO nanoclusters of a uniform size (∼3 nm) were spontaneously formed, leading to the production of PdO-functionalized ultrathin WO (PdO@WO) nanohybrids. The conversion yield of WO nanosheets from metallic WS nanosheets increased with increasing coverage of PdO nanoclusters on the nanosheet surface. In addition, the conversion of WO nanosheets induced by PdO nanocluster formation was effective only in HO but not in organic solvents, such as -methylpyrrolidone and acetonitrile. A mechanical study suggests that the chemisorption of hydrated Pd precursors on the chalcogens of metallic WS nanosheets leads to their facile oxidation by water molecules, producing WO nanosheets covered with PdO nanoclusters. The as-prepared PdO@WO nanosheets exhibited excellent photocatalytic activity and recyclability in Suzuki cross-coupling reactions of various aryl halides under visible light irradiation.
通过在溶液中剥离其体相来获得超薄二维（2D）WO 纳米片并不容易，因为层间存在强共价相互作用。此外，由于其导带边缘位置不足，它们需要与助催化剂进一步功能化，以扩大其在光催化有机反应中的适用性。在这里，我们报告了一种通过直接转化金属 WS 纳米片同时生产和功能化超薄 2D WO 纳米片的化学方法，该方法是通过在 HO 中纳米片表面上自发形成和沉积 PdO 纳米簇来实现的。当将化学剥离的金属 WS 纳米片简单地混合在 HO 中的 KPdCl 中，在温和条件（50°C，1 小时）下，它们被转化为半导体 WO 纳米片，在其上自发形成均匀尺寸（约 3nm）的 PdO 纳米簇，从而产生 PdO 功能化超薄 WO（PdO@WO）纳米杂化物。WO 纳米片的转化率随着纳米片表面上 PdO 纳米簇覆盖率的增加而增加。此外，仅在 HO 中而不在有机溶剂（如-甲基吡咯烷酮和乙腈）中，通过 PdO 纳米簇形成诱导 WO 纳米片的转化才有效。机械研究表明，水合 Pd 前体在金属 WS 纳米片的硫属元素上的化学吸附导致水分子容易氧化它们，从而产生覆盖有 PdO 纳米簇的 WO 纳米片。所制备的 PdO@WO 纳米片在各种芳基卤化物的 Suzuki 交叉偶联反应中在可见光照射下表现出优异的光催化活性和可回收性。
