氯离子对铜或黄铜表面膜半导体性质的影响

Di Quarto等对Cu在弱酸性溶液中氧化膜层的光电化学进行了较为广泛的研究.关于Cl~-离子的影响,他们认为,在低浓度下(Cl~-]≤5×10~(-2)mol·L~(-1),即质量比0.0029),仅增加Cu 电极的腐蚀速度,而不影响Cu 电极表而氧化层Cu_2O 的半导体特性.但尚未见细致的工作报导:Cl~-离子浓度究竟达到多大时能对Cu 电极氧化膜层的半导体特性产生影响?我们在弱碱性溶液中逐步添加Cl~-,通过在周期性光照(14Hz)下,用锁定放大器测得的光电流i_(ph)对E 的关系,来研究Cl~-对铜或黄铜表面膜层半导体性质的影响.

INFLUENCE OF CHLORIDE IONS UPON SEMICONDUCTOR PROPERTIES OF OXIDE FILMS ON COPPER AND BRASS

The photocurrent-potential relationship for copper and brass electrodes under periodic illumination was obtained during slow (6 mV·s~(-1)) cyclic potential scans with lock-in amplifier in 0.1 molo·L~(-1) Na_2B_4O_7 contianing variable concentration of NaCl. Only cathodic photocurrent was exhibited on photocurrent vs. potential curves in absence of or in the presence of low concentrations of chloride ion in the solution. The minimum concentration of NaCl at which an anodic photocurrent peak appeared is 7.5×10~(-4) g·g~(-1) for copper and 3.8×10~(-3) g·g~(-1) for brass. With the continuous increase of NaCl concentraton the peak area of anodic photocurrent increases and that of cathodic decreases. The appearance of anodic photocurrent peak and its magnitude on photocurrent vs. potential curve may be served as a criterion for the characterization of the corrosion extent of copper material by Cl~-.