树枝状微纳米银催化剂对甲醛的电化学检测

Dentrite-like Ag micronano-catalysts for electrochemical detection of formaldehyde

在Ag(NH3)2+溶液中,在钛基体上电沉积出具有新颖树枝状结构的微纳米银材料,探讨了K+或Ca2+的存在对这种树枝状微纳米银材料的影响.结果表明,在Ca2+存在下形成了尺寸更小的树枝状银(Ag/Ca2+/Ti),研究了这种钛基树枝状微纳米银电极(Ag/Ca2+/Ti)在碱性溶液中对甲醛氧化的电催化活性.循环伏安结果表明,在0.1 mol.L-1NaOH溶液中,甲醛氧化的起始电位为-0.83 V,阳极氧化电流密度随甲醛浓度的增大而明显增加;-0.5 V时的恒电位阶跃研究表明,甲醛浓度和它的稳态氧化电流密度呈现良好的线性关系,甲醛检测灵敏度为1.25 mA.cm-2(mmol.L-1)-1,检测下限18.9μmol.L-1,且乙醛、乙醇和正丁醇的干扰较小.结果表明,电沉积制备的这种细树枝状微纳米银电极(Ag/Ca2+/Ti)对甲醛氧化具有强的电催化活性,且对甲醛检测具有高灵敏度和较好的选择性,有望作为甲醛检测的电化学传感器.

Dentrite-like Ag micronano-materials were prepared by using the electro-deposition process in Ag（ NH3 ） 2＋ solution. The effect of K ＋ , Ca2 ＋ on the formation of the dendritic Ag was investigated. Results showed that the presence of Ca2＋ in the Ag（ NH3 ）2 solution resulted in the formation of smaller dentrite-like silver micronano- catalyst （Ag/Ca2＋/Ti）. The electrocatalytic activity of the Ag/Ca2＋/Ti catalyst towards formaldehyde oxidation in alkaline media was examined. Cyclic voltammetric responses of the Ag/Ca2＋/Ti electrode in 0.1 mol. L -~ NaOH containing HCHO showed a low onset potential of- 0.83 V for formaldehyde oxidation and a rapid increment of formaldehyde oxidation current density with formaldehyde concentration. Chronoamperometric data at - 0.5 V presented a linear increase of the oxidation current density at 600 s with Cnc.o in the range of 0---10 mmol-L-1 HCHO with a HCHO detection sensitivity of 1.25 mA-cm-2 （mmol＇L-1） -1 and detection limit of 18.9 mol. L-1. The presence of acetaldehyde, ethanol or butanol exhibited little effect on the electrochemical detection of HCHO by using the prepared Ag/Ca2＋/Ti as electrocatalyst. Results showed that the Ag/Ca2＋/Ti electrode exhibited high electroactivity for the HCHO oxidation and presented a promising application to electrochemical detection of HCHO with high sensitivity and selectivity.