Self‐Assembled Manganese Sulfide Nanostructures on Graphene as an Oxygen Reduction Catalyst for Anion Exchange Membrane Fuel Cells

Abstract

The development of active, inexpensive, and durable nonprecious-metal electrocatalysts to replace high-cost Pt-based catalysts towards the commercialization of fuel cell technology is the focus in recent years. In this regard, we report a facile one-pot hydrothermal synthesis of self-assembled manganese sulfide on graphene layers (MnS/G), and is recognized as a nonprecious-metal catalyst for the efficient oxygen reduction reaction (ORR) in an alkaline medium. The phase purity and surface morphologies are investigated by using X-ray diffraction and scanning electron microscopic techniques, respectively. Optimized MnS/G with 50 % Mn exhibited excellent ORR properties with onset and half-wave potentials of 0.83 and 0.71 V vs. RHE, respectively. While evaluating the durability, only a 90 mV negative shift in its half-wave potential is observed after 5000 repeated potential cycles, which is also ascertained for up to 48 h of operation at a constant potential by using a chronoamperometric technique with 28 % degradation in the current. The optimized material is utilized as a cathode catalyst in fabricating membrane electrode assembly for performance evaluation in an anion exchange membrane fuel cell. A peak power density of 12 mW cm À2 is realized in H 2 ÀO 2 feeds under ambient temperature and pressure; thus, it looks as an alternative non-preciousmetal catalyst for fuel cell applications. water (18.2 MW cm) used throughout the present work was produced from Milli-Q system, Germany.

Ordered Iron‐ and Nitrogen‐Doped Carbon Framework as a Carbon Monoxide‐Tolerant Alkaline Anion‐Exchange Membrane Fuel Cell Catalyst

“…Moreover, the 30 nm@Fe‐N‐Csample exhibits excellent long‐term durability. As shown in Figure b, with a 0.6 V constant voltage, the output power density of the 30 nm@Fe‐N‐C sample could steadily operate for more than 60 h with only 4.65 % performance degradation, which shows substantially higher stability than commercial Pt/C with more than 18.6 % retention of its initial electrochemical activity after 60 h, which is also superior to the durability performance investigated in recent reports . The LSV curve of the 30 nm@Fe‐N‐C sample was acquired before and after 1000 cycles testing.…”

“…As shown in Figure 6b,w ith a0 .6 Vc onstant voltage,t he output power density of the 30 nm@Fe-N-C sample could steadily operate for more than 60 hw ith only 4.65 %p erformance degradation, which shows substantially higher stability than commercial Pt/C with more than 18.6 %r etention of its initial electrochemical activitya fter 60 h, whichi sa lso superiort ot he durability performancei nvestigated in recent reports. [46,47] TheL SV curve of the 30 nm@Fe-N-C sample was acquired before anda fter 1000 cycles testing. As shown in Figure6c, the ORR onset potential and half-wavep otential did not change, which provedt hat the catalyst activity was not significantlyr educed,b ut the diffusion-limiting current of the samples decreased from 4.7 to 4.2 mA cm À2 .Chronoamperometric responses were monitored to characterize the CO tolerance of the catalysts.T he 30 nm@Fe-N-Ccatalyst shows as ignificantly better tolerance to CO than commercial Pt/C (Figure 5d), indicating that the as-obtained 30 nm@Fe-N-C catalyst holds great potential as an ultra-stable ORR catalyst.…”

A comprehensive review on water management strategies and developments in anion exchange membrane fuel cells

“…Further, oxygen reduction reaction (ORR) is more favorable in alkaline electrolytes reducing the ORR overpotential and allowing to use lower catalyst loading contributing to reduce environmental pollution [13,14]. The other benefit of AEMFC is that alkaline cell atmosphere give raise a possibility to adopt broad category of materials as bipolar plates and other cell components [8,10,[14][15][16].…”

“…, MoS2 etc. )[16,70,71] and carbon nanomaterials (graphene, MWCNTs and their derivatives)[40,[78][79][80][81] could be employed as electrocatalysts in AEMFC. Since none of them is really commercialized, the state of art is based on Pt supported on carbon black with an anion exchange ionomer (AEI).…”

Efficient oxygen reduction activity on layered palladium phosphosulphide and its application in alkaline fuel cells

“…Wang et al [25] synthesized cobalt sulfide/graphene composite and have shown efficient electrocatalysis for ORR in alkaline medium. Sahu et al reported metal sulphide (Mo, Co and Mn) [26][27][28] -graphene composites as efficient ORR catalyst and evaluated their performance in AEMFCs environment.…”