Electrochemical Codeposition of Platinum and Molybdenum Oxides: Formation of Composite Films with Distinct Electrocatalytic Activity for Hydrogen Peroxide Detection

Abstract

The electrochemical properties of gold electrode surfaces modified by molybdenum oxide films intercalated with platinum microparticles have been described. The incorporation of Pt microparticles at the oxide film was characterized by PIXE (particle induced X-ray emission) spectroscopy. The modified electrode showed electrochemical activity at around À 0.5 V in 50 mmol L À1 Na 2 SO 4 supporting electrolyte (pH 3), corresponding to the reduction of protons at platinum sites and further transfer of hydrogen atoms to form reduced molybdenum oxides (bronzes). At 0.1 V, the MoO 3 / Pt electrode showed a better performance for hydrogen peroxide oxidation than on platinized gold electrodes. The solution pH has a marked effect on the voltammetric profile and best responses for hydrogen peroxide were obtained at the 5.0 to 6.0 pH range. The activation of the electrode by polarization at negative potentials was also studied and a mechanism by which more platinum sites are available as a consequence of this process was proposed. Calibration plots for hydrogen peroxide were highly linear (r 0.9989) in the 0.2 to 1.6 mmol L À1 concentration range, with a relative standard deviation (RSD) < 1%.

Novel Electrochemical Microsensor for Hydrogen Peroxide based on Iron‐Ruthenium Hexacyanoferrate Modified Carbon Fiber Electrode

“…As a consequence, there is still growing interest in the modification of electrodes and microelectrodes with various organic and inorganic materials [18 -21]. These include polymeric materials and enzymes [9], clays [18], transition metal oxides [19], and polynuclear transition metal hexacyanometallates [20,21]. Among them, the transition metal hexacyanoferrates, particularly Prussian blue (PB) and its analogues, have received significant attention as mixed-valence polynuclear compounds/mediators.…”

Sensores eletroquímicos: considerações sobre mecanismos de funcionamento e aplicações no monitoramento de espécies químicas em ambientes microscópicos

“…Há artigos de revisão e textos mais aprofundados em que se discutem fundamentos e aplicações de ferramentas espectroscópicas na análise de superficies 3,[71][72][73][74] . Nosso grupo tem empregado algumas das técnicas acima relacionadas na investigação da estrutura de filmes de óxidos de molibdênio, nos quais se depositaram micropartículas de metais nobres, como platina, paládio e ródio 75,76 . A formação de óxidos e hidróxidos de cobre também foi averiguada empregando-se EDS ("energy dispersive spectroscopy") e os resultados indicaram a forte relação entre a composição dos filmes e a atividade eletroacatalítica do processo de oxidação do etanol com o potencial aplicado ao eletrodo de trabalho 77 .…”

Nanostructured Molybdenum Oxides from Aluminium-Based Intermetallic Compound: Synthesis and Application in Hydrogen Evolution Reaction

“…As an alloying element it enhances the corrosion resistance and mechanical properties of steels [ 1 , 3 ]. Molybdenum compounds have an array of applications as well—gas sensors [ 4 , 5 ], heterogeneous catalysis [ 6 , 7 ], electrocatalysis [ 4 , 8 ], capacitors [ 4 , 9 ], electrochromism [ 10 , 11 ], photochromism [ 4 , 12 ], and lithium-ion batteries [ 13 , 14 ]. Chalcogenide derivatives of Mo have been evidently favorable as building blocks in nanomaterial design in photocatalysis and hydrogen evolution reaction (HER) [ 15 , 16 ].…”