Research
1. Electrocatalytic water splitting for hydrogen production
Owing to the increasing concerns over environmental issues and dependence on fossil fuels, electrocatalytic water splitting into hydrogen (H2) and oxygen (O2) is considered as an essential strategy to provide green and sustainable energy. However, the two half electrochemical reactions involved in a water splitting process, namely, the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), are kinetically sluggish, leading to significant electrode overpotentials, and thus requires efficient electrocatalysts to improve energy efficiency. We research various highly active OER and HER electrocatalysts using the noble metal, transition metal, metal oxide and heterogeneous catalyst by tailoring atomical/electronical properties.
2. Photoelectrochemical water splitting for hydrogen production
Efficient utilization of solar energy could alleviate many energy and environmental issues, as the solar energy irradiating the surface of the Earth (1.3 x 105 TW) exceeds the current global human energy consumption (1.6 x 101 TW). The photo-assisted electrochemical water oxidation based on band-gap excitation, photocatalytic and photoelectrochemical (PEC) water splitting on semiconducting materials has received tremendous attention for production of renewable hydrogen from water on a large scale. We research various highly active photocatalyst, photoanode and cathode materials by bandgap engineering and construct the tandem device with various types of solar cells for unbiased water splitting system.
3. Electrocatalyst for ammonia oxidation reaction
The implementation of renewable chemical fuels that are derived from abundant carbon-free feedstocks will be a key step in addressing future global energy demands. NH3 is a prominent, large-scale and renewable carbon-free energy source that could augment fossil-based fuels as renewable sources of energy are realized for NH3 production (i.e., N2 reduction). NH3 is easily stored and distributed using an established infrastructure, and is produced on an enormous scale from abundant N2 and fossil-derived H2 by the Haber–Bosch process. Due to its high energy density and flexibility as a fuel, NH3 can be a H2 storage medium or oxidized directly in NH3 fuel cells. We research various types of electrocatalysts for NH3 oxidation for unveiling the catalytic origin to understand how to cleave N–H bonds and construct the full cell with hydrogen evolution reaction (HER) electrocatalyst for overall N2 and H2 production.
4. Electrocatalyst for metal-air battery
Among the various energy conversion and storage technologies, metal–air batteries with high power and energy densities are promising candidates for the operation of portable devices and electric vehicles. The metal-air batteries have a higher specific energy density than conventional rechargeable Li-ion batteries (200–250 W h kg-1). However, the sluggish reaction kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) on air-cathode side causes the high overpotential gap and low round-trip efficiency during charge and discharge process, limiting to achieve the high theoretical energy density performance. We research highly active ORR and OER bifunctional electrocatalyst to reduce the overpotential gap and apply it to sodium (Na) – air battery and Zinc (Zn) – air battery to achieve superior energy density performance.
5. Electrode materials for energy storage devices
Nanostructured electrode materials have received tremendous interest due to their unique mechanical/electrical properties and overall behavior contributed by the complex synergy of bulk and interfacial properties for efficient and effective energy storage. The booming development of nanotechnology affords emerging but effective tools in designing advanced energy material. We research nanostructured electrode materials for electrochemical energy storage devices, including lithium, sodium and potassium ion batteries and supercapacitors.
6. Operando/In-situ synchrotron X-ray characterization
There are three types of measurements to analyze the reactions: ex-situ, in-situ and operando measurements. For ex-situ measurement, the cells are stopped at the desired potential, flowed by extraction of the electrode from the electrochemical cell in order to analyze it with the desired technique. For in-situ measurement, the cells are stopped to measure directly the electrode inside the cell at OCV. Operando measurement is performed while the cell is cycling. Most results from in-situ and operando measurements are similar, but the results from ex-situ measurement can be very different, since the state can be changed through relaxation process once cell is stopped. Operando/in-situ (especially, synchrotron based) X-ray techniques are very powerful to obtain important information for revealing reaction mechanisms of electrodes. We research the mechanistic studies of electrocatalyst and rechargeable battery electrodes using operando synchrotron X-ray based methods such as X-ray absorption spectroscopy and X-ray diffraction.
7. Density Functional Theory (DFT) calculation
Most of researchers are using advanced computational approaches based on density functional theory (DFT) and other methods that are able to predict materials properties. First principle calculations conduct accurate analyses and are better and better able to calculate materials properties at atomic/electronic levels based on quantum mechanics, statistical thermodynamics, classical mechanics and electrodynamics. We research rapid and reliable answers for a range of materials issues, especially related to materials design for energy conversion and storage.
