Research

Materials for Energy Conversion & Environmental Engineering

We are conducting research on energy conversion materials for catalytic reactions including electrochemical, photoelectrochemical, and photocatalytic reactions. Our research aims to develop environmentally friendly and sustainable energy solutions to address issues such as global warming and energy scarcity.

1. Material Design

(1) Electrocatalysts

We are currently engaged in experimental material design to optimize the efficiency and stability of specific catalytic reactions. For the electrochemical reactions, new materials with unique nanostructures or atomic configurations including binary or ternary metals and semiconductors are under investigation. our investigation encompasses strategies such as defect management involving vacancies and grain boundary engineering, precise atomic-level adjustments as seen in single-atom catalysts, and the incorporation of tandem structures. These approaches are being carefully considered as we embark on the endeavor of designing electrocatalysts.

(2) Photocatalysts and Photoelectrodes

For the photocatalytic and photoelectrochemical reactions, various cocatalysts are applied on the conventional semiconductors (Si, GaN) and emerging semiconductors (perovskite, oxides) to fully harness the potential of abundant and clean solar energy. The research approach involves the interaction between catalysts and semiconductors at the heterointerface, thereby influencing electronic dynamics. Additionally, we are actively investigating the catalytic performance effects arising from lattice mismatch-induced strain on these materials.

2. Catalytic Reactions

-Electrochemical Reactions: Electrochemical reactions involve the conversion of electrical energy into chemical energy through the redox (reduction-oxidation) process. This typically occurs at the interface between an electrode and an electrolyte.

-Photoelectrochemical Reactions: Photoelectrochemical reactions combine light absorption and electrochemical processes on a photoelectrode. In photoelectrochemical cells, photoelectrodes absorb photons from light and generate electron-hole pairs. These charge carriers are then utilized for redox reactions at the photoelectrode-electrolyte interface.

-Photocatalytic Reactions: Photocatalytic reactions involve the use of a photocatalyst to facilitate chemical transformations under light irradiation. The photocatalyst absorbs photons, creating electron-hole pairs that can drive redox reactions on its surface or interact with nearby molecules. This process is employed in environmental applications, such as using photocatalysts to break down pollutants in air or water, and in energy-related applications like artificial photosynthesis for converting carbon dioxide into fuels using sunlight.

(1) Water Splitting

Water splitting is a chemical reaction in which water (H2O) is separated into its constituent elements, hydrogen (H2) and oxygen (O2). This process involves breaking the strong bonds between hydrogen and oxygen atoms through the application of energy. We are investigating two processes of water reduction (= H2 evolution) and water oxidation (= O2 evolution) reactions using electrocatalysts, photoelectrodes, and photocatalysts.

(2) CO2 Reduction

CO2 reduction is a process aimed at converting greenhouse gas, CO2, into valuable chemicals or fuels using electrochemical, photoelectrochemical, and photocatalytic reactions. This process addresses both environmental concerns by reducing CO2 emissions and energy challenges by providing a means to store renewable energy in chemical forms.

(3) NOx and N2 Reduction

NOx reduction refers to the process of reducing nitrogen oxides (NOx), which are a group of highly reactive gases or ions that include NO, NO2 gases, and NO2- or NO3- ions. These chemicals are pollutants produced from chemical processes, such as those occurring in vehicles and industrial facilities. NOx emissions contribute to air pollution, smog formation, and adverse health effects.

N2 reduction refers to the reduction of nitrogen gas (N2) to form ammonia (NH3). This is a method to replace the Haber-Bosch process, which is an industrial method to synthesize NH3 from nitrogen and hydrogen gases at high temperatures and high pressure with the emission of massive CO2 gas. It's important to note that both NOx and N2 reduction are complex processes with environmental and technological implications, and they are areas of ongoing research and development to address pollution and sustainability challenges.