化学镀镍体系次亚磷酸钠氧化中间产物的ESR研究

化学镀镍是借助 Na H2 PO2 在具有催化活性金属表面的阳极氧化将溶液中的镍离子还原成金属镍 .伴随镍的沉积 ,表面同时有氢气析出 .同位素研究表明 1,2 ] ,析出的氢气一部分为溶液中 H+或 H2 O的阴极还原 ,另一部分来自 Na H2 PO2 的阳极氧化过程 .Meerakker等3～ 5 ] 认为 ,Na H2 PO2 的氧化经历了H2 PO-2 H+ HPO-.2 异相前置转化步骤 ,HPO-.2 阴离子自由基发生阳极氧化的同时伴有 H复合生成氢气过程 .而另一些研究者 6～ 8] 认为 ,Na H2 PO2 的氧化过程为 H2 PO-2 + H2 O H2 PO-3 + 2 H,仅有 H自由基生成 ,并不产生 H…

An ESR Investigation of the Intermediate Obtained from Oxidation of Sodium Hypophosphite in the Process of Electroless Nickel Deposition

The radical intermediate, which is produced in the process of electroless nickel plating, was detected in the presence of water-soluble trap α-4-pyridy1-N-tert-buty1 nitrone(POBN) or α-phenyl-tert-buty1 nitrone(PBN) by electron spin resonance(ESR) spectroscopy. The results obtained indicated that a 16-line(g=2.006 1, a^β_C-H=1.98×10^-4 T, a^γ_P-H=3.32×10^-4 T, a_N=a_P=15.93×10^-4 T) or a 18-line (g=2.004 9, a^β_C-H=a^γ_P-H=2.38×10^-4 T, a_P=17.72×10^-4 T, a_N=16.20×10^-4 T) ESR spectrum was observed in the process of electroless nickel plating when spin trap PBN or POBN was added. The spectra-line patterns and hyperfine coupling parameters were greatly indentical with those in the solution composed of Ti³⁺(0.01 mol/L)+H₂O₂(0.05 mol/L)+H₂PO₂^-(0.01 mol/L)+POBN or PBN(0.01 mol/L). Therefore, the spin adducts formed in the process of electroless nickel plating could be ascribed to the adducts belonging to HPO₂^-· and POBN or PBN and it follows that the anion radical HPO₂^-·was really produced from the oxidation of sodium hypophosphite in the process of electroless nickel plating.