Pt−Ag Catalysts as Cathode Material for Oxygen-Depolarized Electrodes in Hydrochloric Acid Electrolysis

Abstract

Pt-Ag nanoparticles were prepared on a glassy carbon (GC) surface by pulsed electrodeposition and tested using cyclic voltammetry and scanning electrochemical microscopy (SECM) with respect to their possible use as catalyst material for oxygen reduction in 400 mM HCl solution. For comparison, a Pt catalyst was investigated under similar conditions. The redox competition mode of scanning electrochemical microscopy (RC-SECM) was adapted to the specific conditions caused by the presence of Cl(-) ions and used to visualize the local catalytic activity of the Pt-Ag deposits. Similarly prepared Pt deposits were shown to dissolve underneath the SECM tip. Pt-Ag composites showed improved long-term stability toward oxygen reduction as compared with Pt even under multiple switching off to open-circuit potential in 400 mM HCl.

Study of Porosity-Dependent Oxygen Reduction at Porous Platinum Tips Using Scanning Electrochemical Microscopy

“…6 Increasing ORR current density (including n value) and more positive E 1/2 were observed with increasing pore size. Due to very thin Pt film on carbon substrate, however, the catalytic activity of carbon substrate is not negligible.Rotating ring and disk electrode (RRDE) 9-11 and scanning electrochemical microscopy (SECM) [12][13][14][15][16][17][18][19][20][21] have been generally used to study the ORR activity and mechanism at various metallic thin film catalysts using Pt or Au electrodes for H 2 O 2 detection. Especially, SECM has been proven to be useful for studying the mechanism and activity associated with electrode reactions with high collection efficiency, minimizing experimental errors, such as the effects of the resistive potential drop in solution, the charging current, etc.…”

Fabrication of soft gold microelectrode arrays as probes for scanning electrochemical microscopy

“…This includes catalysts for energy conversion [21,22] and materials for light harvesting [23]. The potential for electrochemical investigation of material libraries has been demonstrated, in which the inspection of specimens coated with the material libraries that measure square millimeters or square centimeters rather than a few square micrometers is required.…”

Polythiophene‐Assisted Vapor Phase Synthesis of Carbon Nanotube‐Supported Rhodium Sulfide as Oxygen Reduction Catalyst for HCl Electrolysis

“…[1] Recently, the energy efficiency has been significantly enhanced by replacing the traditional means of hydrogen production with the oxygen reduction reaction (ORR) using an oxygen-depolarized cathode. [2,3] Platinum has long been studied as electrocatalyst for the ORR; however, its application is limited by its poor stability in the highly corrosive HCl electrolyte and by the strong adsorption of chloride ions onto the platinum surface, which may lead to kinetic limitations for the ORR. [1,4,5] Recently, the rhodiumbased chalcogenide Rh 17 S 15 was found to be a very active and highly stable catalyst for the ORR in HCl.…”

“…[4] Methods reported for the synthesis of rhodium sulfide catalysts include direct reaction of metallic rhodium with elemental sulfur in xylene, [6] deposition-precipitation (DP) from solution, [4,7] decomposition of carbonyl precursors, [4] using H 2 S for post-treatment, [3,8,9] and using thio-containing compounds or thiols. [4,10] In general, catalysts prepared from precipitation using H 2 S and prepared from thio-containing compounds at fixed pH showed the best performance, which, however, is still below that of state-of-the-art platinum-based catalysts.…”

“…For comparison, pure polythiophene (without CNTs) was synthesized in the liquid phase, and thermally treated at 650 8C in He with or without impregnated RhCl 3 . The results, shown in Figure 5 a, suggest that the charge transfer resistance of CNTs (trace 5) and of carbonized polythiophene (trace 4) is much higher than that of the three Rh-S/CNT samples.…”