Membraneless microfluidic fuel cells (MMFCs) remove the physical membrane in conventional fuel cells and are considered one of the promising micropower supplies for portable electronic devices. However, a co-laminar flow pattern should be maintained to avoid fuel crossover, which goes against the integration of the cell and its applicability. Herein, we adopt activated carbon (AC) as the cathode catalyst to trigger the oxygen reduction reaction (ORR) and construct a novel single-flow MMFC (SF-MMFC). Benefitting from the selective catalytic property, the unfavorable fuel-crossover issue is successfully avoided, and device construction is extremely simplified. One single reactant solution containing both fuel and electrolyte can successfully maintain SF-MMFC stable operation. The device delivers a volumetric power density of 218.6 mW cm–3; nevertheless, the ORR catalytic performance for AC powders is poorer than that of commercial Pt/C cathode. More importantly, the capital power production per unit cathode cost is 200 W $c–1. The utilization of catalyst with selective catalytic performance can accelerate the application potential of MMFC technology in powering portable electronic devices.
Methanol is a volatile fuel which can be fed into microfluidic fuel cells in vaporized form. However, the methanol oxidation reaction is relatively sluggish compared with the hydrogen oxidation reaction . Therefore, a novel dual fuel microfluidic fuel cell system powered by both methanol and methanol-derived hydrogen via photocatalysis is developed, which can achieve much improved cell performance while eliminating the hydrogen transportation , storage and safety issues. Pt/P25 is adopted as the photocatalyst which photo-reforms the methanol to hydrogen in the fuel tank. The intermediate during the photoreforming process can also be fed into the microfluidic fuel cell as a fuel. Different cell performance can be achieved by varying the fuel-water mix ratios in the tank. By optimizing the ratio, the peak power density can be increased by more than 10 times when the system is exposed to simulated solar light (3 suns) illumination.
Membraneless microfluidic fuel cell (MMFC) is expected to be a promising candidate of next-generation power supplies for portable devices due to its intrinsic advantages of compact construction, sufficient power density and environmental friendliness . However, it remains a challenge to CO 2 bubbles management with a controllable strategy under the acidic operational conditions. Herein, a facile and effective strategy that enables promotion of CO 2 bubbles detachment by manipulating the generated CO 2 bubbles with the aid of bioinspired gradient anode is proposed. The geometry gradient successfully boosts CO 2 bubbles transport along flow direction and wettability-gradient facilitates the unidirectional CO 2 bubbles penetration. The successful cooperation can benefit the manipulation of CO 2 bubble generation, transport, and departure on the anode. The MMFC equipped with the proposed anode is capable of operating stably at the extremely high current density of 130 mA cm −2 . Compared with MMFC based on the conventional anodes, the power density and the limiting current density are significantly increased by 30% and 60%, respectively. The present study solves the problem of unstable power supply caused by CO 2 bubbles at high current density (>50 mA cm −2 ), benefiting the powering the practical devices constantly.
A Ru@Pt core–shell nanoparticles decorated graphene-carbon nanotube composite was produced as a porous anode for a flow-through direct methanol microfluidic fuel cell (MFC). The composite was characterized by TEM and SEM, which reveals that the size of the nanoparticles is less than 5 nm and the pore size of the porous electrode is less than 10 µm. TEM image showed that the nanoparticles were evenly distributed in the carbon substrate without agglomeration. The carbon nanotubes (CNT) increased the composite conductivity by connecting the graphene oxide nanosheets together. An orthogonal flow air-breathing microfluidic fuel cell combining the advantages of co-flow and counter flow MFC was designed to compare the electrode performances and a maximum specific power of 13.1 mW/mg catalyst was achieved with 1 M methanol in 1 M KOH as supporting electrolyte, which outperformed most others’ works in the literature.
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