Bimetallic nickel-molybdenum/tungsten nanoalloys for high-efficiency hydrogen oxidation catalysis in alkaline electrolytes

Abstract

Hydroxide exchange membrane fuel cells offer possibility of adopting platinum-group-metal-free catalysts to negotiate sluggish oxygen reduction reaction. Unfortunately, the ultrafast hydrogen oxidation reaction (HOR) on platinum decreases at least two orders of magnitude by switching the electrolytes from acid to base, causing high platinum-group-metal loadings. Here we show that a nickel-molybdenum nanoalloy with tetragonal MoNi4 phase can catalyze the HOR efficiently in alkaline electrolytes. The catalyst exhibits a high apparent exchange current density of 3.41 milliamperes per square centimeter and operates very stable, which is 1.4 times higher than that of state-of-the-art Pt/C catalyst. With this catalyst, we further demonstrate the capability to tolerate carbon monoxide poisoning. Marked HOR activity was also observed on similarly designed WNi4 catalyst. We attribute this remarkable HOR reactivity to an alloy effect that enables optimum adsorption of hydrogen on nickel and hydroxyl on molybdenum (tungsten), which synergistically promotes the Volmer reaction.

Subnanometer high-entropy alloy nanowires enable remarkable hydrogen oxidation catalysis

“…In addition, we compared the hydrogen binding energy (HBE) and the oxhydryl binding energy (OHBE) of HEA SNWs/C [33][34][35] . Compared with the strong bindings of H * on Pt (111) and PtRu (111), the binding strength of H * on HEA SNWs/C has been significantly weakened to an appropriate level near the 0 eV (an ideal value for H * binding), leading to the improved HOR activity over HEA SNWs/C (Fig.…”

Solvent-free microwave synthesis of ultra-small Ru-Mo2C@CNT with strong metal-support interaction for industrial hydrogen evolution

“…Exchange current density (J 0 ) is another important parameter reflecting translation kinetics, which can provide the internal electron transfer rate between the electrode and the catalyst surface 55 . The exchange current density (J 0 ) of the catalyst was extracted from the linear fitting of the micropolarization region (−10 to 10 mV) 56 . The exchange current density of Ru-Mo 2 C@CNT was 4.3 mA cm −2 (Fig.…”

High-Performance Ru 2 P Anodic Catalyst for Alkaline Polymer Electrolyte Fuel Cells

“…[1][2][3] Currently, Pt remains the most advanced ORR electrocatalyst for PEMFCs, but its use is limited by its high cost and scarcity. 4,5 Due to their harsh acidic environment, most nonnoble metals and their alloys are labile and hence lead to low durability in PEMFCs. 6 As an alternative to PEMFCs, alkaline polymer electrolyte fuel cells (APEFCs) have received considerable attention by virtue of the development of nonnoblemetal-based electrocatalysts with Pt-like stability and high activity in cathode for ORR in alkaline electrolytes.…”

“…6 As an alternative to PEMFCs, alkaline polymer electrolyte fuel cells (APEFCs) have received considerable attention by virtue of the development of nonnoblemetal-based electrocatalysts with Pt-like stability and high activity in cathode for ORR in alkaline electrolytes. 4,7,8 However, the kinetics of anodic HOR in alkaline solution, even for the most advanced Pt-based catalysts, are approximately two to three orders of magnitude more sluggish than in acidic solution, 9,10 which means that more Pt-based catalysts are required to overcome the sluggish anodic HOR in APEFCs. Consequently, developing Pt-free materials as highly active and stable anodic catalysts for APEFCs is highly desirable.…”

“…19,20 Despite the fact that some Ni-based nonprecious metal electrocatalysts have been reported for catalyzing alkaline HOR, their catalytic performances are still far below the practical application in APEFCs. 4,[6][7][8]21,22 Most of the APEFCs with Ni-based materials as the anodes only show the peak power density around 0.1 W cm −2 . [22][23][24] As the cheapest metal in the platinum group of metals (PGM), Ru-based electrocatalysts have received considerable attention.…”