In this research work, a simple method of silver nanoparticles’ self-synthesis in chitosan (CH) biopolymer hydrogels without utilizing a reducing agent is shown. The synthesized material was used as a catalyst in different reduction reactions. For this purpose, different amounts of CH powder were dissolved in acidic aqueous solutions and then crosslinked it with the formaldehyde solution to make a CH biopolymer hydrogel. Among all the prepared samples, a CH hydrogel prepared from a dense solution was found to be suitable for this study because of good mechanical stability. For the self-synthesis of silver nanoparticles inside hydrogel, it was immersed in an aqueous solution of AgNO₃ (10 mM) for 3 days at room temperature. The color of the chitosan hydrogel changed to brown from transparent which indicated the successful formation of silver nanoparticles on CH hydrogel (Ag-CH). No reducing agent for conversion of the Ag¹⁺ ions to nanoparticles in this whole synthesis method. Instrumental techniques such as FESEM, XRD and EDX analysis confirmed the successful preparation of Ag-CH. The Ag-CH was checked as a catalyst in the 2-nitrophenol (2-NP) and acridine orange (ArO) reduction reactions. Both reactions were carried out at high rate constants (2-NP = 0.260 min⁻¹, ArO = 0.253 min⁻¹) by using the Ag-CH hydrogel catalyst. In addition, we discussed the mechanism of action of the reducing agent, the effect of k_app on the two reduction reactions of Ag-CH and the recyclability.

在这项研究工作中，展示了一种不使用还原剂的壳聚糖（CH）生物聚合物水凝胶中银纳米粒子自合成的简单方法。合成的材料在不同的还原反应中用作催化剂。为此，将不同量的CH粉溶解在酸性水溶液中，然后将其与甲醛溶液交联以制备CH生物聚合物水凝胶。在所有制备的样品中，由于具有良好的机械稳定性，因此发现由浓溶液制备的CH水凝胶适用于本研究。为了在水凝胶内部自合成银纳米颗粒，将其浸入AgNO ₃的水溶液中（10 mM）在室温下放置3天。壳聚糖水凝胶的颜色从透明变为棕色，这表明在CH水凝胶（Ag-CH）上成功形成了银纳米颗粒。在该整个合成方法中，没有用于将Ag ¹⁺离子转化为纳米颗粒的还原剂。FESEM，XRD和EDX分析等仪器技术证实了Ag-CH的成功制备。在2-硝基苯酚（2-NP）和a啶橙（ArO）还原反应中检查了Ag-CH作为催化剂。通过使用Ag-CH水凝胶催化剂，两个反应均以高速率常数（2-NP ＝ 0.260min ^-1，ArO ＝ 0.253min ^-1）进行。此外，我们讨论了还原剂的作用机理，k _app的作用 Ag-CH的两种还原反应和可回收性