Constructing a Cathode Catalyst Layer of a Passive Direct Methanol Fuel Cell with Highly Hydrophilic Carbon Aerogel for Improved Water Management

Abstract

Nitrogen-doped porous carbon materials show excellent water adsorption ability by forming strong hydrogen bonding between water molecules and the doped atoms. When these porous carbon materials are used to construct a water management layer (WML) of a passive direct methanol fuel cell (DMFC), high water concentration and hydraulic pressure formed inside the cathode catalyst layer would facilitate the water recovery from cathode to anode. In this paper, a highly hydrophilic nitrogen-doped carbon aerogel was synthesized by the carbonization of hydrogel precursors composed of resorcinol, formaldehyde, and graphene oxide under ammonia, and it was used for the first time to construct the WML for liquid-feed and vapor-feed passive DMFCs. The results show that the WML significantly improves the output performance of the liquid-feed DMFC by enhancing the water recovery, which is characterized and proved by the smaller cathode polarization, the slightly increased anode polarization, and a released cathode water flooding situation. A new method was also proposed to study the in situ methanol crossover of DMFCs, which confirmed that the methanol crossover during the discharge was reduced by the WML. As for the vapor-feed DMFCs, the WML reduces both the cathode and anode polarizations significantly, which increases the output performance greatly. This study opens a new window for the design and optimization of the membrane assembly electrode of DMFCs.

A facile synthesis for nitrogen‐doped carbon catalyst with high activity of oxygen reduction reaction in acidic media

“…The facile synthesis of nitrogen‐doped carbon catalysts was as follows 41 . A 4.0 mL GO with 5% mass fraction, 16.0 mL water, 0.665 mL formaldehyde with 37% mass fraction, and 0.495 g resorcinol were mixed in sequence and stirred at 300 rpm for over 0.5 hour.…”

A Critical Assessment on Functional Attributes and Degradation Mechanism of Membrane Electrode Assembly Components in Direct Methanol Fuel Cells

“…In a study, using the Sessile-drop method, it is observed that decreasing hydrophobicity leads to a small contact angle of water droplets in the GDL fibers [215]. Despite the irreversible performance reduction, there is a chance that the physical degradation of electrodes, especially the cathode, will have implications for water drainage characteristics during a prolonged test, potentially increasing the water flooding conflict [216]. However, the number of lite is limited with linked water flooding behavior to morphological alterations in the CCL during protracted DMFC operation.…”

Aerogels as Catalyst Support for Fuel Cells

“…Fig. 1 [22] shows the schematic setup of a direct methanol FC or DMFC. A microwave-assisted polyol process was used by Hong Zhu et al [23] to synthesize Pt-Au based on carbon aerogel (CA).…”

“…Fig. 2 [22] shows water flooding at cathode current collectors, a challenging problem in the working of a DMFC.…”

“…Thus, making way for oxides as an alternative to be used as an electrocatalyst in energy storage devices. Weijian Yuan et al [48] synthesized nitrogen-doped CA using resorcinol, formaldehyde and GO and carbonization of the aforementioned precursors and hydrogel under ammonia obtaining an ECSA value of 41.57 m 2 g −1 and a peak power density of 22.41 mW cm −2 . The aerogel showed a very high surface area and superior doping of N and O atoms.…”