Carbon-supported bimetallic Pd–Ir catalysts for alkaline sulfide oxidation in direct alkaline sulfide fuel cell

Abstract

In this paper, carbon-supported palladium (Pd) and its alloys with iridium (Ir) were investigated for the purpose of alkaline sulfide oxidation and ultimately for application as anodes in direct alkaline sulfide fuel cell (DASFC). Physical and electrochemical characterizations, such as X-ray diffraction, transmission electron microscopy, energy dispersive X-ray, cyclic voltammetry, linear sweep voltammetry, I-V analysis, and electrochemical impedance spectroscopy were carried out. Pd 9 Ir 1 /C exhibited the highest activity, showing the lowest onset potential and the highest current density, mass activity, and specific activity. The maximum power density of a DASFC single cell with a Pd 9 Ir 1 /C anode was 33.98 mW cm -2 at 70°C, which was 35 % higher than that obtained with Pd/C. It is thought that the incorporation of more oxophilic Ir into Pd promoted the adsorption of OH ads at a lower potential, and Pd 9 Ir 1 /C led to optimal OH ads coverage, which played a catalytic role and thus resulted in the best performance.

Biomimetically Synthesized Hierarchical TiO2-Graphitic Carbon as Anodic Catalysts for Direct Alkaline Sulfide Fuel Cell

“…Six milligrams of the fabricated catalysts was dispersed in 6 mL of IPA/DIW (1/5, v/v) via sonication to obtain homogeneity of the ink, and then 3.5 μL of the ink was dripped onto a glassy carbon electrode to achieve a loading of 0.15 mg cm –2 . After drying in an oven overnight, 3.5 μL of Tokuyama ionomer (AS-4, 5 wt %) was also dripped on the catalyst layer to enhance the mechanical strength of the catalyst layer. , The as-prepared electrodes were then subjected to CV in a potential range from −0.8 to 0.5 V in N 2 -purged 1 M Na 2 S + 3 M NaOH at a scan rate of 10 mV s –1 and at a rotation speed of 2000 rpm with rotating disk electrode (RDE) equipment.…”

“…After drying in an oven overnight, 3.5 μL of Tokuyama ionomer (AS-4, 5 wt %) was also dripped on the catalyst layer to enhance the mechanical strength of the catalyst layer. 11,12 The as-prepared electrodes were then subjected to CV in a potential range from −0.8 to 0.5 V in N 2 -purged 1 M Na 2 S + 3 M NaOH at a scan rate of 10 mV s −1 and at a rotation speed of 2000 rpm with rotating disk electrode (RDE) equipment.…”

“…For instance, various compounds such as metal sulfides and heteropolyacids have been reported to produce quite meaningful power output. Bimetallic alloys are other promising candidates; it was found that bimetallic palladium–cobalt or palladium–iridium showed higher activity than Pd itself and especially the widely active noble metal Pt. − However, the performance of the anodic catalyst, which is in fact an essential condition, needs to be further improved in order to meet the economical aspects for the implementation of the DASFC-based H 2 S capture technology.…”