贵金属纳米颗粒由于具有独特的物理特性而被广泛应用于催化，光热治疗及表面增强光谱等领域，然而银纳米颗粒的化学稳定性差，金纳米颗粒的催化性能依赖其大小，这严重限制了其进一步应用。本文通过一种简单温和的湿化学方法合成了具有较好单分散性的球形金银合金纳米颗粒。根据表征结果可知，合金颗粒的形貌尺寸均一，金和银两种金属元素分布均匀，属于一种多晶的晶体结构。研究结果表明，通过改变金和银的摩尔比，能够很容易实现金银合金纳米颗粒表面等离激元共振峰的调控。此外，由于金和银两种元素的协同效应，金银合金纳米颗粒同时具有较好的稳定性和较强的催化性能，且要远好于单组分的金纳米颗粒和银纳米颗粒。该研究为构建多种较高性能的合金纳米材料提供了新思路，为减少环境中芳香族硝基有机污染物提供了可能途径。

The prominent third-order nonlinear optical properties of WTe2 films are studied through the Z-scan technique using a femtosecond pulsed laser at 1030 nm. Open-aperture (OA) and closed-aperture (CA) Z-scan measurements are performed at different intensities to investigate the nonlinear absorption and refraction properties of WTe2 films. OA Z-scan results show that WTe2 films always hold a saturable absorption characteristic without transition to reverse saturable absorption. Further, a large nonlinear absorption coefficient β is determined to be 3.37×103cm/GW by fitting the OA Z-scan curve at the peak intensity of 15.603GW/cm2. In addition, through the slow saturation absorption model, the ground state absorption cross section, excited state absorption cross section, and absorber’s density were found to be 1.4938×10 16cm2, 1.2536×10 16cm2, and 6.2396×1020cm 3, respectively. CA Z-scan results exhibit a classic peak–valley shape of the CA Z-scan signal, which reveals a self-defocusing optical effect of WTe2 films under the measured environment. Furthermore, a considerable nonlinear refractive index value n2 can be obtained at 1.629×10 2cm2/GW. Ultimately, the values of the real and imaginary parts of the third-order nonlinear s