Clean energy

Production of hydrogen fuels from water using electricity generated from renewable energy sources such as solar and wind can provide a sustainable and clean fuel supply for human use. Currently, low efficiency and high cost are the major hurdles for producing affordable hydrogen fuel from the electrochemical splitting of water. We design novel nanostructured catalysts that are made entirely of Earth-abundant materials and can catalyse water electrolysis at an unprecedented efficiency. Our electrodes have been commercialised and successfully applied in a number of industrial plants.

Proton exchange membrane fuel cells fueled with hydrogen have been considered the ultimate energy source. However, their costs have remained one of the barriers towards wide-scale commercialisation. We are particularly tackling this challenge via the development of porous nonprecious metal catalysts, with the aim of reducing and replacing platinum group metals with more available materials. We are specialised in operando techniques for characterising the catalysts and membrane electrode assemblies in home-built single cells and stacks.

Fossil fuels have historically been the primary feedstock for petroleum-based products and industrial chemicals. Apart from the impact that fossil fuels pose on the environment, they are generally mined in remote locations and require massive infrastructure for processing and distribution before they are even refined. One promising solution is to reduce CO2 itself to petrochemical feedstock, which could cater to the unprecedented consumerism of society and simultaneously reduce the anthropogenic emissions of CO2 in the atmosphere to restore the natural carbon cycle. We are designing advanced catalysts that are efficient, selective, stable, and low cost for converting CO2 into useful chemicals and fuels.

Ammonia is an important commodity in the hydrogen economy due to its high energy capacity, easy storage and transportation. The Haber-Bosh process is vital for the fertilizer industry due to its high ammonia production rate. However, non-ambient operating conditions, alongside its energy-intensive nature and sophisticated infrastructure have hampered its utilization as a green and decentralized system. On the other hand, the electrochemical nitrogen reduction reaction (NRR) at ambient conditions is a suitable and sustainable alternative, while the selectivity of the catalysts needs to be improved to increase the ammonia generation rate.

The large-scale harvest of intermittent renewables (solar and wind) calls for efficient energy storage devices to integrate them into electric grids. Comparing with other types of charge carriers (Li+, Na+, K+), proton possesses the smallest ionic radius and the unique Grotthuss’s conduction mechanism for achieving ultrafast transport and high power density. We have developed a new-concept aqueous proton battery with high cycling performance and capacity, demonstrating application potentials for large-scale energy storage. Novel cathode and anode materials and home-made in-situ characterization devices are being developed to understand the electrode/electrolyte interface and the structure evolution of electrode materials during proton insertion.

Ionic liquids (ILs), liquids that contain essentially only ions, are novel electrolytes and often have extremely low vapour pressure (environmentally friendly), low combustibility, excellent thermal stability and wide electrochemical windows. We are particularly interested in a class of protic ionic liquids (PILs) because their fluidities and attendant conductivities tend to be much higher than aprotic ILs, for reasons that are not completely clear. These novel ionic liquids will be explored as electrolytes electrochemical applications such as fuel cells and Li-air batteries.

Interfacial photoelectron transfer kinetics is crucial to the operation of a photocatalyst. However, relatively little is known so far about the factors that control the kinetics of electron transfer (ET) at the photocatalyst/electrolyte interface. Conventional electrochemical techniques encounter problems at these interfaces such as ohmic effects, charging currents, and parallel processes such as corrosion. We have applied scanning electrochemical microscopy (SECM) to solve this challenge. This technique allows reliable steady state measurements of rate constants and transfer coefficients for fast reactions and is also free of problems with ohmic effects, photocorrosion and photopassivation.