Methanol Oxidation at Pt−Cu, Pt−Ni, and Pt−Co Electrode Coatings Prepared by a Galvanic Replacement Process

Abstract

Platinized Cu, Ni, and Co deposits have been formed on glassy carbon (GC) electrode substrates by a twostep process, whereby a controlled amount of the transition metal was electrodeposited onto GC and subsequently partially exchanged for Pt upon immersion of the Cu/GC, Ni/GC, and Co/GC electrodes into a chloroplatinic acid solution. The spontaneous partial replacement of the transition metal by Pt resulted in Pt(Cu)/GC, Pt(Ni)/GC, and Pt(Co)/GC electrodes whose composition and depth profile were obtained by energy-dispersive spectrometry (EDS) and sputter-etch Auger electron spectroscopy (AES). Following electrochemical conditioning (involving electrode exposure to the oxygen and hydrogen evolution potential regimes), all deposits displayed typical Pt surface electrochemistry in acid solutions. Pt(Cu) catalysts exhibited enhanced electrocatalytic activity for methanol oxidation both during voltammetric and constant potential experiments. The behavior of Pt(Ni) and Pt(Co) depended on the method of assessment; in short-term voltammetric experiments, they were inferior to pure Pt, whereas in long-term constant potential experiments they outperformed it. The superior methanol oxidation activity of Pt(Cu) among all catalysts tested is interpreted in terms of the effect of Cu, Ni, and Co on methanol dissociative chemisorption and CO poison removal at/from the Pt surface.

Dye-sensitized photoelectrochemical cell on plasmonic Ag/AgCl @ chiral TiO 2 nanofibers for treatment of urban wastewater effluents, with simultaneous production of hydrogen and electricity

“…Within this wide contest, wastewater 6 previously considered as a waste is increasingly being used as a valuable resource for 7 producing fresh water, energy and fertilizing nutrients (N and P). For instance, the 8 wastewater"s organic content can be converted into methane gas through the anaerobic 9 process [1], and microbial fuel cell (MFC) [2,3] may also be a viable route for the 10 production of energy from wastewater treatment.…”

“…For instance, the 8 wastewater"s organic content can be converted into methane gas through the anaerobic 9 process [1], and microbial fuel cell (MFC) [2,3] may also be a viable route for the 10 production of energy from wastewater treatment. Photocatalytic oxidation using 11 titanium dioxide (TiO 2 ) is an effective method for the removal of chemically stable 12 contaminants, it requires no chemicals input or output and TiO 2 is inexpensive and 13 non-toxic [4][5][6][7][8]. The photocatalytic oxidation of contaminants is initiated by the 14 excitation of TiO 2 , which results in the promotion of an electron (e-) to the conduction 15 band (CB) and creation of a hole (h+) in the valence band (VB) of TiO 2 [9].…”

“…One major innovating aspect of the present study 4 is the replacement of the redox couples (such as I -/I 3 -) in DSSCs with organic and 5 inorganic compounds naturally occurring in urban wastewater, which collectively can 6 act as an effective electrolyte and also reduced the dye in excited state to stable state. 7 Although dyes have been reported to be unstable in water, they may have a temporary 8 sensitization effect. Under an ideal situation, organic contaminants may be oxidized by 9 an excited dye in the photoanode, while nitrate and heavy metal could be reduced in the 10 cathode ( Fig.…”

“…In a typical 4 synthesis, C18-D-Glu (0.06 g, 0.16 mmol) was dissolved in a mixture of methanol 5 (27.2 g) and deionized water (160 ml) while stirring at room temperature. After the 6 mixture was stirred for 10 min, TDA (0.58 g, 75% in isopropanol, purchased from TCI) 7 was added to the mixture with stirring at 55°C. The mixture was allowed to react at 8 55 °C with stirring for 2 h. The products were collected by centrifugal separation and 9 dried by freeze drying at -60 °C, which resulted in a pale yellow powder.…”

“…Prior to irradiation, twelve fabricated DSPC cells (the volume of each cell was 12.5 6 were vertically fixed into an oscillation box, and were all shaken in the dark, for 40 7 to establish adsorption-desorption equilibrium of the solution species with the 8 electrodes. Then water samples for analysis were taken when all 12 cells were 9 irradiated for two hours using an AM 1.5 solar simulator (Oriel) equipped with a 150 10 xenon light and AM 1.5G type filter (Newport, 81094).…”