Electrocatalysis: Synthesis to Devices
Research Topics
Electrochemical Organic Oxidation Reaction
Electrochemical organic oxidation in paired water electrolysis is a sustainable approach for converting waste materials, such as plastics and biomass-derived compounds, into value-added precursor products at the anode while simultaneously enhancing hydrogen production efficiency at the cathode. By utilizing electrical energy, this method enables the selective oxidation of organic molecules, which have lower electrochemical potentials than water oxidation, thereby generating valuable chemicals. In the case of plastic waste, hydrolysis followed by electrochemical oxidation yields useful intermediates like succinate and formate. Similarly, biomass-derived molecules such as hydroxymethylfurfural (HMF) can be electrochemically oxidized into high-value compounds like 2,5-furandicarboxylic acid (FDCA), a key precursor for bioplastics. This approach not only offers a greener and more energy-efficient pathway for upcycling waste into industrially relevant chemicals but also improves the overall efficiency of hydrogen generation.
Fuel Cells
Proton Exchange Membrane (PEM) Fuel Cells:
A proton exchange membrane (PEM) fuel cell is an electrochemical device that converts hydrogen into electricity through a redox reaction, offering high efficiency and zero emissions. At the anode, hydrogen molecules split into protons and electrons on an electrocatalyst, with protons migrating through the polymer electrolyte membrane while electrons travel through an external circuit, generating electrical power. At the cathode, oxygen from the air reacts with protons and electrons to form water, the only byproduct. Operating at 60–80°C, PEM fuel cells provide rapid startup and high power density, making them ideal for transportation and stationary applications. However, challenges include sluggish oxygen reduction reaction (ORR) kinetics, platinum catalyst costs, and membrane hydration management. Researchers focus on improving catalyst efficiency, developing durable membranes, and optimizing water and heat management to enhance performance and longevity. Advancements in these areas are key to commercializing PEM fuel cells for sustainable energy solutions.
Oxygen Reduction Reaction (ORR) in PEM Fuel Cells:
The oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells occurs at the cathode, where molecular oxygen (O₂) is reduced to water (H₂O) via a multi-step, four-electron transfer process. In acidic PEM fuel cells, ORR proceeds via a four-electron pathway: O₂ is adsorbed onto the catalyst surface (typically Pt-based), followed by sequential proton and electron transfer steps, leading to bond cleavage and water formation. ORR is inherently sluggish due to the strong O=O bond and complex reaction mechanism, necessitating highly active electrocatalysts to enhance efficiency and reduce overpotential losses. Research efforts focus on developing advanced catalysts, such as Pt alloys and non-precious metal alternatives, to improve ORR kinetics and lower fuel cell costs.
Hydrogen Evolution Reaction (HER)
The Hydrogen Evolution Reaction (HER) is a fundamental electrochemical process for generating hydrogen gas (H₂) from water, playing a crucial role in sustainable energy technologies such as water electrolysis and fuel cells. HER occurs at the cathode of an electrolyzer, where protons (H⁺) in acidic media or water molecules (H₂O) in alkaline media are reduced to hydrogen gas (H₂). Efficient HER catalysts, such as platinum-based materials, reduce energy consumption and improve hydrogen generation efficiency. Our research focuses on developing cost-effective, high-performance catalysts to enhance HER kinetics and stability for scalable green hydrogen production.
Oxygen Evolution Reaction (OER)
Water splitting through electrolysis driven represents a promising pathway to sustainable energy, converting water molecules into hydrogen and oxygen to produce green hydrogen. Critical for improving the economic viability of this process is the oxygen evolution reaction (OER), a crucial yet challenging step that currently limits the efficiency of water electrolysis systems.
The OER's inherently slow reaction kinetics present a significant technical hurdle. To overcome this bottleneck, research is focusing on developing advanced electrocatalysts – materials that can accelerate the reaction. The ideal catalyst must demonstrate high catalytic activity, maintain long-term stability under operating conditions, and be cost-effective for commercial implementation.
Our research group is at the forefront of this challenge, developing novel electrocatalysts for OER. We specialize in transition metal oxides and MXene-based materials, which show promising potential for efficient oxygen evolution. These advanced materials combine the robust catalytic properties of transition metals with the unique structural advantages of MXenes, offering new possibilities for high-performance water splitting systems.
Optimizing OER catalysts is essential for reducing energy losses and improving the economic viability of green hydrogen production. This research area represents a critical intersection of materials science and sustainable energy technology, with important implications for the broader adoption of hydrogen as a clean energy carrier.
Electrolyzers
Electrolyzers are essential for sustainable hydrogen production, enabling the conversion of water into hydrogen and oxygen through electrochemical reactions. Our research focuses on anion exchange membrane (AEM) electrolyzers, developing efficient catalysts and optimizing device performance to advance water electrolysis technology. In our lab, we utilize multiple electrolyzer setups to investigate catalyst activity, stability, and system efficiency under controlled conditions. Our facilities include:
- Two AEM electrolyzer setups, equipped with mass flow meters for precise volume measurement of produced gases and electrolyte flow rate adjustment to analyze mass transport effects.
- Various electrolyzer cells for catalyst evaluation at different scales:
- Two homemade cells (area: 1 cm² and 4 cm²) for fundamental electrocatalyst studies
- Two commercial cells — a 5 cm² Dioxide Materials cell and a 6.25 cm² redox.me cell — allowing for catalyst testing under application-relevant conditions
- Membrane electrode assembly (MEA) fabrication, where we integrate our catalysts into self-prepared MEAs. We employ membranes from different suppliers for performance evaluation.
- Electrochemical testing infrastructure, featuring a range of potentiostats for detailed electrochemical characterization:
- Three PalmSens4 potentiostats and a four-channel PalmSens multipotentiostat
- One Metrohm Autolab potentiostat
- Two CH Instruments potentiostats
- Two Zahner potentiostats (Zennium Pro & Zennium E4), along with a booster for high-current applications (PP211)
A key aspect of our research involves the use of MXenes—specifically Ti₃C₂Tx, Ti₂CTx, and V₂CTx—which are integrated with our catalyst materials to enhance the electrochemical performance of AEM electrolyzers. The unique properties of MXenes, such as their high conductivity and tunable surface chemistry, provide significant advantages for efficient hydrogen production. By combining advanced catalyst development with MXenes and real-world electrolyzer testing, our research contributes to improving the efficiency and scalability of green hydrogen production, supporting the transition to a sustainable energy future.
Photo electrochemical (PEC) water splitting
Photo electrochemical (PEC) water splitting is a promising method for sustainable hydrogen production by utilizing solar energy to drive the electrolysis of water into hydrogen and oxygen. This process involves a photo electrode, typically a semiconductor material, which absorbs sunlight and generates electron-hole pairs that facilitate redox reactions at the electrode surface. The photocathode enables hydrogen evolution, while the photo anode supports oxygen evolution. The efficiency of PEC water splitting depends on factors such as light absorption, charge separation, and catalytic activity. Research efforts focus on developing stable and efficient materials, such as transition metal dichalcogenides (TMDs) and MXene hybrids, to enhance the performance of PEC cells for large-scale hydrogen production.
Electrochemical Hydrogen Pump
An electrochemical hydrogen pump (EHP) is an electrolytic cell that produces high-pressure hydrogen at the cathode. It utilizes a proton exchange membrane (PEM) in a zero-gap configuration and is powered by an external electricity supply. At the anode, hydrogen is oxidized, generating protons that pass through the PEM while electrons are supplied to the cathode, where the hydrogen evolution reaction occurs, producing hydrogen. Since only protons pass through the ionically conductive membrane, an EHP can also be used to separate hydrogen from gas mixtures.
The test rig operates at temperatures ranging from 30°C to 75°C, with a maximum output pressure of 30 barg. The EHP has the flexibility to operate with samples that have a geometric area of either 5 cm2 or 25 cm2. Our research focuses on optimizing operating conditions for peak performance, exploring non-platinum group metal catalysts for the hydrogen evolution reaction at the cathode.