铂电极上氰离子电化学行为的现场红外反射吸收光谱及电化学研究

本文用电化学方法和电化学调制现场FTIR光谱方法研究了CN~-/pt体系的行为。对0.5 mol L~(-1)NaCN+0.5mol L~(-1)NaF/pt体系, 在-0.8至1.0伏(相对饱和甘汞电极)电势区内, 可观测到四个红外吸收峰, 位置为2076、2087—2095, 2138和2170cm~(-1), 分别对应于溶液中的CN~-, 吸附态的CN~-, pt~(2+)-CN~-配合物及NCO~-。在此伏电势范围内, Pt电极上总存在吸附态的CN~-, 其吸收峰位随电势正移而移向高波数。当电势正于0.2伏时, 电极上发生了两种不可逆电化学反应, 分别生成Pt(CN)_2或Pt(CN)_4和NCO~-。当电势正于0.6伏时, NCO~-发生进一步的氧化反应, 生成CO_2和N_2气泡。

IN-SITU FTIR REFLECTION-ABSORPTION SPECTROSCOPIC STUDIES OF CYANIDE ON PLATINUM ELECTRODES

The behaviors of cyanide ions on platium electrode were studied using cyclic voltammetry and in-situ FTIR spectroelectrochemistry. The system was 0.5 moIL~(-1) NaCN +0.5 moIL~(-1) NaF/Pt. Four bands near 2076, 2087—2095, 2138 and 2170 cm~(-1) were found when potential changed staircasely from -0.80 to 1.00 V(vs.SCE). These bands were attributed to CN-(2076 cm~(-1)) in the solution, adsorbed CN~-(2087-2095 cm~(-1)), complex compound Pt(CN)_4~(2-) and/or Pt(CN)_2(2138 cm~(-1)) and solution species NCO~- (2170 cm~(-1), respectively. The band near 2087 cm~(-1) for adsorbed CN~- showed blue shift with increasing potential. The experiment results showed that the adsored CN~- existed over the whole potential range studied. Two electrochemical reactions were observed as potential was made more positive than about 0.20 V with the products being Pt(CN)~2_4 and/or Pt(CN)_2 and NCO~- and surface complexes took place, generating CO_2 and N_2.