Control of galvanic replacement reaction between Cu nanowires and Ag species under vacuum filtration for transparent conductive films with long-term durability
Control of galvanic replacement reaction between Cu nanowires and Ag species under vacuum filtration for transparent conductive films with long-term durability
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DOI：
10.1016/j.colsurfa.2020.125809
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发表时间：
2020-10
期刊：
影响因子：
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通讯作者：
S. Yokoyama;Yuta Umemoto;K. Motomiya;T. Itoh;Hideyuki Takahashi
中科院分区：
文献类型：
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作者：
S. Yokoyama;Yuta Umemoto;K. Motomiya;T. Itoh;Hideyuki Takahashi
在铜纳米线(NW)表面镀银被广泛用于制备耐久的透明导电膜。虽然通常采用CuNWS和Ag物种之间的电偶置换反应(GRR)，但由于反应速度快，得到的银层不均匀，导致薄膜不耐久。本文通过真空过滤控制柠檬酸溶液中铜纳米粒子表面与银络合物之间的GRR，得到均匀的镀银纳米粒子作为耐久薄膜。柠檬酸去除了铜NW表面的杂质，并对其进行了表面改性。当柠檬酸吸附到NWS上时，可以延缓铜在水溶液中的溶解，从而能够调节GRR的银浓度、溶液体积和温度。通过在真空过滤下降低这三个因素中的一部分或全部，精确地控制了GRR。在受控反应中，较慢的反应速率导致了部分Ag晶体在表面的生长。随着溶液体积的增加，生长的不均匀程度增加，产生了较大的表面不规则性。在快反应速率和高Ag浓度下，Ag物种在短时间内与CuNW表面反应均匀，导致CuNW表面的不规则性较少，Ag层较厚。GRR后，由于铜结间生长的Ag晶体降低了接触电阻，降低了CuNWS的方块电阻。在具有厚银层的透明CuNW薄膜中，方块电阻在高温(130℃)和标准恶劣条件(85℃和85%相对湿度)下保持300h。
Ag coatings on Cu nanowire (NW) surfaces are widely studied for making durable transparent conductive films. Although the galvanic replacement reactions (GRRs) between Cu NWs and Ag species were usually employed, non-uniform Ag layers were obtained due to their rapid reaction rates, leading to non-durable films. Herein, the GRR between Cu NW surfaces and Ag complexes in citric acid solutions was controlled by vacuum filtration, obtaining uniform Ag-coated NWs for durable films. Citric acid removed the surface impurities from the Cu NW surfaces and also modified the surfaces. While adsorbed to the NWs, citric acid delayed the Cu dissolution in aqueous solution, enabling regulation of the Ag concentration, solution volume, and temperature of the GRR. The GRR was precisely controlled by lowering some or all of these three factors under vacuum filtration. In the controlled reactions, the slow reaction rates caused partial Ag crystal growth on the surfaces. The heterogeneity of the growth increased with solution volume, producing large surface irregularities. At fast reaction rates with high Ag concentrations, the Ag species uniformly reacted with the Cu NW surface within a short time, leading to Cu NWs with fewer surface irregularities and thicker Ag layers than at slow reaction rates. After the GRR, the sheet resistance of the Cu NWs was lowered because the Ag crystal growth between the Cu junctions decreased the contact resistance. In transparent Cu NW films with a thick Ag layer, the sheet resistance was retained for 300 h at high-temperature (130 °C) and under standard harsh conditions (85 °C and 85% relative humidity).