Electroreduction of nitrobenzene on titanium electrode implanted with platinum

The titanium substrates were bombarded with 5 x 10(17) ions cm(-2) of plati num. The surface composition of implanted electrode and concentration-depth profiles of various elements were measured by AES. The chemical state of P t in titanium electrode implanted with platinum (Pt/Ti) was detected by X-r ay photoelectron spectroscopy (XPS). The process and mechanism of the elect roreduction of nitrobenzene (NB) in 0.1 M NaOH solution at Pt/Ti electrode have been investigated by cyclic voltammetry, rotating ring-disk electrode (RRDE) and Electron Spin Resonance (ESR) in-situ. The results indicated tha t the electrocatalytic activity of implanted substrates was much more activ e than that of the untreated ones. Meanwhile, the electrocatalytic activity of Pt/Ti electrode was also higher than that of smooth Pr. The NE anion-ra dical. which is the product of one-electron reduction of NE. was detected b y ESR in-situ in conjunction with electrochemical methods. The results of R RDE also showed that the first stage of the electroreduction of NE in alkal ine solution involves formation of an anion-radical that then can be reduce d to phenylhydroxylamine successively. (C) 2000 Elsevier Science S.A. All r ights reserved.