纳米铜电极的制备及其表面拉曼增强效应研究

表面增强拉曼光谱（SERS）是一种超灵敏痕量检测技术，在生物和环境分析等领域得到广泛应用。由于可以得到乙烯等二碳化合物还原产品，铜成为最受瞩目的CO₂电还原催化剂之一。电催化过程中间体的生成和演化是影响催化剂选择性和活性的最关键因素，但电化学中间体高度活泼、寿命短，很难通过普通的方法捕获和研究。本论文旨在制备具有表面拉曼增强效应的铜电极，为下一步二氧化碳在铜表面的电催化还原过程中间体的捕获和研究打下坚实基础。

首先采用电化学沉积法直接制备铜纳米枝晶SERS电极，为了避免引入有机分子表面钝化层，选用卤素离子对纳米颗粒的形貌和尺寸进行调控。并对铜纳米枝晶的电沉积生长机理进行研究。研究结果表明，溴离子通过抑制铜枝晶的生长从而起到了细化铜晶粒的作用。并且在-1.0 V的沉积电位下，以0.1 M溴离子进行调控所制备的SERS铜电极拉曼增强效果最好，其表面拉曼增强因子可达10⁶。

在液相沉淀法合成氢氧化铜纳米片基础上，通过不同还原方法制备SERS铜电极。还原方法包括抗坏血酸还原、硼氢化钠还原、不同电位电化学还原等。研究发现，抗坏血酸还原法得到的铜纳米立方块晶体，存在（220）晶面的择优取向生长，其拉曼增强效果最佳，增强因子大于7×10⁵。

本文制备的纳米铜电极具有优异的拉曼增强性能，拉曼增强因子超过10⁶，为下一步利用SERS光谱原位捕捉二氧化碳还原中间产物、研究二氧化碳还原机理奠定了坚实基础。同时发现抗坏血酸具有诱导铜纳米晶粒（220）择优生长的特性，为优化铜纳米晶体的电催化活性开辟了新思路。

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