Glycerol Is Converted into Energy and Carbonyl Compounds in a 3D-Printed Microfluidic Fuel Cell: In Situ and In Operando Bi-Modified Pt Anodes

Abstract

The combination of energy and chemical conversion can be achieved by designing glycerol fuel cells. However, the anode must promote the reaction at onset potentials low enough to allow a spontaneous reaction, when coupled to the cathodic reaction, and must be selective. Here, we build a threedimensional (3D)-printed glycerol microfluidic fuel cell that produces power concomitantly to glycolate and formate at zero bias. The balance between energy and the two carbonyl compounds is tuned by decorating the Pt/C/CP anode in situ (before feeding the cell reactants) or in operando (while feeding the cell with reactants) with Bi. The Bi-modified anodes improve glycerol conversion and output power while decreasing the formation of the carbonyl compounds. The in operando method builds dendrites of rodlike Bi oxides that are inactive for the anodic reaction and cover active sites. The in situ strategy promotes homogeneous Bi decoration, decreasing activation losses, increasing the open-circuit voltage to 1.0 V, and augmenting maximum power density 6.5 times and the glycerol conversion to 72% at 25 °C while producing 0.2 mmoL L −1 of glycolate and formate (each) at 100 μL min −1 . Such a performance is attributed to the low CO poisoning of the anode, which leads the glycerol electrooxidation toward a more complete reaction, harvesting more electrons at the device. Printing the microfluidic fuel cell takes 23 min and costs ∼US$1.85 and can be used for other coupled reactions since the methods of modification presented here are applied to any existing and assembled systems.

Interchangeable Biomass Fuels for Paper-Based Microfluidic Fuel Cells: Finding Their Power Density Limits

“…Half-cell measurements showed that the poisoning effect is more intense in high concentrations, which was also reported for PDMS-based μFCs . The three-hydrated carbons make the surface reaction very complex to understand ,,, but certainly improve electron harvest compared to methanol.…”

“…The mixed-media configuration allied to the use of porous electrodes in a flow-through configuration has been used to boost the output power of a μFC fed by biomass-derived alcohols. − Methanol, ethylene glycol, ethanol, and glycerol have been investigated as potential fuels, theoretically producing 6, 10, 12, and 14 electrons per molecule completely oxidized, respectively . Although the cleavage of the C–C bonds of ethanol, ethylene glycol, and glycerol makes it difficult to convert them into CO 2 (CO 3 2– in an alkaline medium) on planar electrodes, − the flow-through configuration increases reactant usage, increasing the efficiency of conversion. , …”

Killing Two Birds with One Stone: Upgrading Organic Compounds via Electrooxidation in Electricity-Input Mode and Electricity-Output Mode

“…Up to now, most prevailing electrodes and or photoelectrons focus on the planar structure, which suffers from limited reactants diffusion and sluggish mass transfer, thus resulting in overoxidation of valuable chemicals [ 106 , 107 ]. Recently, microfluidic nanostructures have been reported and fabricated to circumvent the aforementioned drawbacks due to the use of 3-D channels for precise product control and enhanced mass transfer [ 106 , 107 ]. Qu and co-workers [ 106 ] constructed a microfluidic photo-electrochemical architecture with 3-D microflow channels, which was fabricated with defect WO 3 /TiO 2 heterostructures on porous carbon.…”

“…Cauê A. Martins and co-workers [ 107 ] developed a 3D-printed microfluidic glycerol fuel cell that generates power concomitantly to formate and glycolate. They intelligently tuned the balance between the output energy and the two carbonyl compounds generated via decorating the Pt/C/carbon paper anode in situ and before feeding reactants, or operando with Bi (while feeding reactants).…”

Glycerol (photo)electro-oxidation on carbon supported Ag nanoparticles modified with low amounts of Pt. Activity, selectivity and the effect of visible-light irradiation

“…The results are relatively similar to those for glycerol showed in figure S3 and in our previous work [5], but with some important differences. Starting by the similarities, it is possible to observe that both the currents attained and the potentials when the 1) Several syntheses of Ag/C nanoparticles can be tested to improve the electrochemical activity and or the visible-light absorption [16,21,22,25], 2) new ways of doing the galvanic replacement and other methods to deposit the noble metal (Pt or Pd) on the surface of Ag/C can be tested [16,20,21], 3) the materials must be used in real devices, i.e., electrolyzers [41], microfluidic fuel cells [42], etc. We believe that, by further optimizing the preparation of materials, these Ag-based NPs will easily surpass the performances of the benchmark Pt/C and Pd/C catalysts.…”