High‐Performance Direct Methanol Fuel Cells with Precious‐Metal‐Free Cathode

Abstract

Direct methanol fuel cells (DMFCs) hold great promise for applications ranging from portable power for electronics to transportation. However, apart from the high costs, current Pt‐based cathodes in DMFCs suffer significantly from performance loss due to severe methanol crossover from anode to cathode. The migrated methanol in cathodes tends to contaminate Pt active sites through yielding a mixed potential region resulting from oxygen reduction reaction and methanol oxidation reaction. Therefore, highly methanol‐tolerant cathodes must be developed before DMFC technologies become viable. The newly developed reduced graphene oxide (rGO)‐based Fe‐N‐C cathode exhibits high methanol tolerance and exceeds the performance of current Pt cathodes, as evidenced by both rotating disk electrode and DMFC tests. While the morphology of 2D rGO is largely preserved, the resulting Fe‐N‐rGO catalyst provides a more unique porous structure. DMFC tests with various methanol concentrations are systematically studied using the best performing Fe‐N‐rGO catalyst. At feed concentrations greater than 2.0 m, the obtained DMFC performance from the Fe‐N‐rGO cathode is found to start exceeding that of a Pt/C cathode. This work will open a new avenue to use nonprecious metal cathode for advanced DMFC technologies with increased performance and at significantly reduced cost.

Atomically Dispersed Fe‐Nx/C Electrocatalyst Boosts Oxygen Catalysis via a New Metal‐Organic Polymer Supramolecule Strategy

“…The ORR activity and H 2 O 2 yields of the studied catalysts were investigated by the rotating ringdisk electrode (RRDE) measurements in O 2 -saturated 0.5 m H 2 SO 4 electrolyte. [2,[35][36][37] The ORR activity of SA-Fe-N-1.5-800 is also superior to that of Fe-N-KJ-800 ( Figure S12, Supporting Information), further confirming the advantages of using SA as a Fe immobilizer and carbon source for developing M-N-C catalysts relative to traditional carbon supports. A substantial improvement in ORR activity of the studied catalysts, reflected by a remarkable positive shift in the onset and half-wave potentials (E 1/2 ), is achieved only after the addition of SA.…”

“…[35] Obviously, there is nearly no change in ORR polarization curves of SA-Fe-N-1.5-800 catalyst in the presence or absence of 1.0 m methanol ( Figure S16, Supporting Information), demonstrating much improved methanol and CO tolerance of the developed catalyst compared to Pt/C catalyst. [35] Obviously, there is nearly no change in ORR polarization curves of SA-Fe-N-1.5-800 catalyst in the presence or absence of 1.0 m methanol ( Figure S16, Supporting Information), demonstrating much improved methanol and CO tolerance of the developed catalyst compared to Pt/C catalyst.…”

Engineering Favorable Morphology and Structure of Fe‐N‐C Oxygen‐Reduction Catalysts through Tuning of Nitrogen/Carbon Precursors

“…These carbon composite catalysts have many advantages over other oxide‐based NPMCs, including low cost, simplicity of functionalization, high surface area, excellent mechanical and electronic properties, and sufficient electrochemical durability under harsh environments . Generally, a high‐temperature treatment (800–1100 °C) in an inert atmosphere (e.g., N 2 or Ar) of a complex mixture including nitrogen/carbon and Fe precursors with/without carbon templates is the common approach to preparing Fe‐N‐C catalysts . The nitrogen/carbon and Fe rich compounds are carbonized together, which is accompanied by direct doping of N and Fe into the carbon matrix.…”

Electrocatalytic Water Splitting and CO2 Reduction: Sustainable Solutions via Single‐Atom Catalysts Supported on 2D Materials

“…The Fe‐ and N‐doped porous carbons are considered as one of the most promising ORR catalysts . Although the Fe/N‐doped C catalysts show relatively good performance, their slightly high overpotential, about 60 mV less than commercial Pt/C in acidic environment, is attributed to the different states of the active sites . Furthermore, the design of metal–N–C configuration is difficult due to the formation of uncontrollable metal clusters at a higher temperature, leading to a relatively low catalytic activity and hard‐to‐understand catalytic mechanisms .…”