Electrochemistry Research Group

Microfluidic Fuel Cells - Nanomaterials - Alcohol and glucose electrooxidation Electrochemical devices - 3D-printed instruments and materials

The Electrochemistry Research Group

The Electrochemistry Research Group was created in 2015 by Prof. Dr. Cauê Alves Martins in Dourados, Mato Grosso do Sul, Brazil. ERG is now hosted by the Instituto de Física from the Universidade Federal de Mato Grosso do Sul (InFi-UFMS).

Our research involves development and evaluation of electroactivity of nanocatalysts for fuel cells applications, mainly involving, synthesis of nanomaterial, investigation of catalytic parameters and 3D-printed instrumentation.

Our latest publications!

This study unveils a novel role of bare graphite as a catalyst in glycerol electrooxidation and hydrogen evolution reactions, challenging the prevailing notion that current collectors employed in electrolyzers are inert. Half-cell experiments elucidate the feasibility of glycerol oxidation and hydrogen production on bulk graphite electrodes at potentials exceeding 1.7 V. The investigation of varying glycerol concentrations (0.05 to 1.5 mol L–1) highlights a concentration-dependent competition between glycerol electrooxidation and oxygen evolution reactions. Employing an H-type glycerol electrolyzer, polarization curves reveal significant activation polarization attributed to the low electroactivity of the anode. Glycerol electrolysis at different concentrations yields diverse product mixtures, including formate, glycolate, glycerate, and lactate at the anode, with concurrent hydrogen generation at the cathode. The anolyte composition changes with glycerol concentration, resulting in less-oxidized compounds at higher concentrations and more oxidized compounds at lower concentrations. The cell voltage also influences the product formation selectivity, with an increased voltage favoring more oxidized compounds. The glycerol concentration also affects hydrogen production, with lower concentrations yielding higher hydrogen amounts, peaking at 3.5 V for 0.05 mol L–1. This model quantitatively illustrates graphite's contribution to current and product generation in glycerol electrolyzers, emphasizing the significance of background current and products originating from current collectors if in contact with the reactants. These results have an impact on the efficiency of the electrolyzer and raise questions regarding possible extra non-noble "nonparticipating" current collectors that could affect overall performance. This research expands our understanding of electrocatalysis on graphite surfaces with potential applications in optimizing electrolyzer configurations for enhanced efficiency and product selectivity.

Given the current and escalating global energy and environmental concerns, this work explores an innovative approach to mitigate a widely employed commercial herbicide using a direct glyphosate (Gly) photocatalytic fuel cell (PFC). The device generates power continuously by converting solar radiation, degrading and mineralizing commercial glyphosate-based fuel, and reducing sodium persulfate at the cathode. Pristine and modified hematite photoanodes were coupled to Pt/C nanoparticles dispersed in a carbon paper (CP) support (Pt/C/CP) dark cathode by using an H-type cell. The Gly/persulfate PFC shows a remarkable current and power generation enhancement after dual-surface modification of pristine hematite with segregated Hf and FeNiOx cocatalysts. The optimized photoanode elevates maximum current density (Jmax) from 0.35 to 0.71 mA cm–2 and maximum power generation (Pmax) from 0.04 to 0.065 mW cm–2, representing 102.85 and 62.50% increase in Jmax and Pmax, respectively, as compared to pristine hematite. The system demonstrated stability over a studied period of 4 h; remarkably, the photodegradation of Gly proved substantial, achieving ∼98% degradation and ∼6% mineralization. Our findings may significantly contribute to reducing Gly's environmental impact in agribusiness since it may convert the pollutant into energy at zero bias. The proposed device offers a sustainable solution to counteract Gly pollution while concurrently harnessing solar energy for power generation.

Microfluidic fuel cells (μFCs) offer a promising avenue for generating energy from glycerol, utilizing flow-through electrodes to enhance reactant utilization. However, the cathodic reaction must efficiently consume the electrons harvested at the anode side to unlock its full potential. Here, we explore the feasibility of employing liquid oxidants as an alternative to O2 reduction on metal-free carbon paper (CP) cathodes. We investigated the half-cell reactions and the energy conversion in a new reusable 3D-printed μFC. Half-cell reactions predict spontaneous reactions by coupling glycerol electrooxidation in an alkaline medium with O2, Na2S2O8, and HClO from commercial bleach in an acidic medium. The μFC printed using the stereolithography apparatus technique build microchannels to place the Pt/C/CP anode and CP cathodes. The glycerol/Na2S2O8 μFC delivered a maximum of 32.4 mW cm−2, while glycerol/HClO μFC displayed 55.9 mW cm−2. This research sheds light on the potential of liquid oxidants as effective alternatives to O2 reduction, presenting a pathway toward optimizing μFCs and their practical applications in energy conversion from glycerol.

A miniaturized and low-cost electrochemical 3D-printed system for rapid and accurate quantification of ethanol content in ethanol fuel using electrochemical impedance spectroscopy (EIS) was developed. The monolithic design of the system incorporates insulating thermoplastic electrode separators, with only the cover being mobile, allowing for easy assembly and handling. The portable device, measuring approximately 26 × 24 mm, has a maximum capacity of 1 mL, making it suitable for lab-on-a-chip and portable analysis. By utilizing the dielectric constant of ethanol and ethanol fuel mixtures with water, the miniaturized EIS cell quantifies ethanol content effectively. To validate its performance, we compared measurements from four gas stations with a digital densimeter, and the values obtained from the proposed system matched perfectly. Our miniaturized and low-cost electrochemical 3D-printed device can be printed and assembled in two hours, offering a cost-effective solution for fast and precise ethanol quantification. Its versatility, affordability, and compatibility with lab-on-a-chip platforms make it easily applicable, including for fuel quality control and on-site analysis in remote locations.

Paper batteries are self-pumping emerging tools for powering portable analytical systems. These disposable energy converters must be low-cost and must achieve enough energy to power electronic devices. The challenge is reaching high energy while keeping the low cost. Here, for the first time, we report a paper-based microfluidic fuel cell (PμFC) equipped with Pt/C on a carbon paper (CP) anode and a metal-free CP cathode fed by biomass-derived fuels to deliver high power. The cells were engineered in a mixed-media configuration, where methanol, ethanol, ethylene glycol, or glycerol is electro-oxidized in an alkaline medium, while Na2S2O8 is reduced in an acidic medium. This strategy allows for optimizing each half-cell reaction independently. The colaminar channel of the cellulose paper was chemically investigated by mapping the composition, which reveals a majority of elements from the catholyte and anolyte on each respective side and a mixture of both at the interface, assuring the existing colaminar system. Moreover, the colaminar flow was studied by investigating the flow rate by considering recorded videos for the first time. All PμFCs show 150–200 s to build a stable colaminar flow, which matches the time to reach a stable open circuit voltage. The flow rate is similar for different concentrations of methanol and ethanol, but it decreases with the increase in ethylene glycol and glycerol concentrations, suggesting a longer residence time for the reactants. The cells perform differently for the different concentrations, and their limiting power densities are composed of a balance among anode poisoning, residence time, and viscosity of the liquids. The sustainable PμFCs can be interchangeably fed by the four biomass-derived fuels to deliver ∼2.2–3.9 mW cm–2. This allows choosing the proper fuel due to their availability. The unprecedented PμFC fed by ethylene glycol delivered 6.76 mW cm–2, which is the benchmark output power for a paper battery fed by alcohol.

May, 2022 - Reading highlight

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 three-dimensional (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.

June, 2022

The production of 3D graphene-based materials is an alternative to retain the intrinsic properties of 2D graphene, and improve others like specific surface area, porosity, mechanical properties, etc. For practical applications such as electrochemical sensors, the production of electroactive 3D graphene-based composites in one single step with good processability and electrochemical response is extremely desirable. Here, we synthesize 3D composites of crumpled graphene (CG) decorated by copper-based nanoparticles in dry state form without further steps. The aerosol-assisted capillary compression strategy adopted results in copper-based nanoparticles directly connected to CG. The carbon nanostructure controls the nucleation and growth of nanoparticles during capillary compression. We explored the application of the composites as an electrochemical sensor for hydrogen peroxide, and it connects the best performance to the synergism between crumpled graphene and the copper-based nanoparticles.

June, 2022

The world is facing a massive problem regarding the reduction of greenhouse gases emission to the atmosphere allied to the need for new and renewable energy sources. Photocatalytic fuel cells (PFCs) have been proposed as a pathway to reduce the costs of conventional fuel cells (FCs) by designing new and smart semiconductor materials for harvesting solar energy and concomitantly converting chemical energy directly into electricity with zero carbon emissions. A PFC combines two well-defined approaches for clean energy production and fuel generation, the FCs and photoelectrochemical (PEC) systems. Regardless of being new, the PFC community is growing fast, with several papers published and patents required in the literature in the last years. We present herein a tutorial review containing the most important definitions, working principles, theoretical fundaments, and hands-on on building devices and testing half-cell reactions and performance of PFCs. In addition, for the first time, we review the recent developments of batch and microfluidic PFCs, highlighting and critically discussing the pros and cons of each approach for solar energy conversion into electricity and environmental remediation.

July, 2021

Sensors based on 3D-printed pieces made with conductive filaments are promising to decrease the cost and time of analysis. However, the conductivity of these sensors is lower than that necessary for electrochemical detection, requiring postprinting treatment. Considering that the post-treatment is mandatory to date, we used an electrochemical surface modification to convert an insulating plastic into a conductive material, eliminating the need for using a conductive filament. We used cyclic voltammetry to grow polyaniline on a polylactic acid surface in the presence of graphite (GR) in the form of trails. This simple step built a monolithic 3D-printed sensor integrated with a GR working electrode (WE). Such a sensor coupled to a minipotentiostat was used to detect caffeine by chronoamperometry in an aqueous solution with a limit of detection of 57.7 μmol L-1. We also electrodeposited Ru and Cu on the WEs, which were used for H2O2 and glucose sensing with the detection limited to 2.3 and 49.3 μmol L-1, respectively. This technique can be applied to any existing plastic object to manufacture integrated (all-in-one), stable, low-cost, and disposable sensors.

April, 2021

In this work we prepare Pd (1 0 0) preferentially oriented nanoparticles modified with different amounts of Tl and study the CO electro-oxidation reaction on these surfaces in alkaline medium. The analysis is based on cyclic voltammetry coupled with in situ FTIR spectroscopy, and the results are interpreted with the help of a DFT study. In situ FTIR indicates a change in the CO adsorption geometry on Pd surfaces partially covered by Tl, while DFT data reveal that for high Tl coverages CO adsorption is completely inhibited. Based on our findings, by using the proper amount of Tl, one can think in the development of Pd-based catalysts designed to present tolerance to CO poisoning, aiming their application in the electro-oxidation of small organic molecules.

January, 2021

Here we present a planar polydimethylsiloxane (PDMS)-based millifluidic device in which the channel (at a serpentine-shape) and a new design of electrochemical sensor (dual-mode detection) are assembled into a single chip. The platform makes use of a fully integrated reservoir to place the reference electrode, separating it from the flowing stream. The device was properly characterized aiming to evaluate the influences of channel geometries and diameters, and the electrochemical properties were improved compared with the classical reference electrode configuration. To investigate the applicability of the proposed millifluidic device, amperometric detection was used for the analysis of tap and lake water as well as groundwater samples to determine salicylic acid - selected as a model analyte. Our experimental results have demonstrated a successful prospect as amperometric detection in PDMS-based chip and showed high tolerance to disturbance by external action provided in the use of electronic micropipette and no surface inactivation from sample-interference.

Research Interests

Renewable Energy - Fuel Cells

Fuel cells produce energy with low environmental impact since these devices convert chemical energy from fuel (H2, glucose or alcohols) into electrical useable power in a cleanly and efficiently electrochemical process. Fuel cell is comprised of many individual cells grouped together to form fuel cell stack.

  • Researches about fuel cell can be roughly divided in:
  1. Anode: materials and reactions;
  2. Cathode: materials and reactions;
  3. Membrane: materials and processes;
  4. Single cells: applying those materials and investigating performance;
  5. General engineering: applying and developing news systems.

ERG is currently interested in fronts 1 and 5.


Anodes and cathodes of fuel cells are made of platinum nanoparticles (NPs) immobilized on carbon black. These NPs do not have the long-term stability and activity required, which is one of the challenges for commercialization of fuel cells. Nanotechnology applied to energy converters involves many fields, including:

  1. Synthesis of metallic NPs: synthesis of single and multi-metallic nanomaterials with high activity and stability;
  2. Nanodesign: synthesis of NPs with controlled shape and size, in attempt to understand the influence of atomic arrangement in surface processes;
  3. New supports: synthesis of new carbon materials, as nanotubes and graphene to partially or completely replace carbon black;
  4. Fundamentals: experimental and theoretical data analysis to help to understand the quantum phenomena involved in surface processes on nanomaterials.

ERG is currently interested in all fronts.

Glucose and Alcohol fuel cells

Pure H2 used as fuel is obtained by electrolysis of water, which is highly expensive. Besides, it is difficult to storage and transport H2. In this context, the development of direct alcohol fuel cells (DAFCs) - particularly those fed with methanol, ethanol and glycerol - has attracted an increasing number of researchers. Ethanol is not toxic and is obtained from biomass. Glycerol is a byproduct of biodiesel fabrication and is less toxic than methanol. Therefore, using alcohols as fuel to feed fuel cells is a way of generating clean energy and added value for these alcohols. Moreover, glucose might be used to feed microfluidic fuel cell to power pacemakers, wearable internet, and low power devices.

Universal devices applied to electrocatalysis

The electrocatalysis field is mainly dedicated to the development of materials and to elucidate processes taking place on the interface solid/liquid. However, not much has been done (comparing the number of publication) concerning the development of new techniques to help researchers in this field. We are dedicated in instrumentation applied to electrocatalysis, in an attempt to build universal devices to help the evaluation of activity and electrochemical stability of new nanomaterials.

Former Students

Universidade Federal de Mato Grosso do Sul
Universidade Federal da Grande Dourados
Universidade Federal da Grande Dourados
Universidade Federal do Mato Grosso do Sul
Universidade Federal do Mato Grosso do Sul
Universidade Federal da Grande Dourados
Universidade Federal da Grande Dourados
Universidade Federal do Mato Grosso do Sul
Universidade Federal de Mato Grosso do Sul
Universidade Federal de Mato Grosso do Sul

Universidade Federal de Mato Grosso do Sul
Kaê de Oliveira Budke (Undergraduate Student)
Universidade Federal de Mato Grosso do Sul

Our Partners

Prof. Jesum Alves Fernandes

  • University of Nottingham (UK)

Prof. Erik Kejang

  • Simon Fraser University (Canadá)

Prof. Giuseppe Abiola Camara

  • Universidade Federal de Mato Grosso do Sul

Prof. Pablo Sebastián Fernadez

  • Universidade Estadual de Campinas

Prof. Gilberto Maia

  • Universidade Federal de Mato Grosso do Sul

Prof. Rodrigo Amorim Bezerra da Silva

  • Universidade Federal de Uberlândia (Monte Carmelo)

Prof. Maria Elisa Martins

  • Universidad Nacional de La Plata, Argentine
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