Abstract

Fuels and chemicals production (including green hydrogen, ammonia, H₂O₂ and etc) using sustainable light-induced catalytic/ electrocatalytic reactions have been considered a potential alternative way to make solar energy storable and transportable. For instances, hydrogen generation from the splitting of water, selective conversion or reduction of CO₂ into chemicals (e.g. methane, methanol and C2-products), selective oxidation of water into hydrogen peroxides (H₂O₂), and chemical reduction of N₂/nitrate pollutants into ammonia are a few good examples of fuels and chemicals production driven by photocatalysis-triggered method. These reactions have demonstrated potential in simultaneously addressing energy and environmental issues.

The above-mentioned light-induced reactions are typically performed using photoactive semiconductors or photocatalysts under natural sunlight (outdoor) or simulated light (indoor), which can conveniently find their respective utilization scenarios. A great number of photoactive semiconductors (be it oxide, nitride, sulphide or others) have attracted attention owing to their affordability, mostly non-toxic, and with considerable theoretical potentials for fuels/ chemicals generation. The scientific challenges in extending their capability in these applications lie on several aspects, such as the extension of the solar spectrum absorption, the overcoming of the charges transportation limitation, and the provision of reasonable photo-stability of the catalytic materials. In addition, demonstration of practicality by developing systems beyond laboratory-scale is currently one of the bottlenecks.

The main approaches of our new group at Chemical Engineering Program, KAUST are in two folds. (1) Traditionally focused on the fundamental understanding of the photoactive catalysts and reactions design; and (2) now the scope and focus are extended to develop larger scale integrated system and installation of devices for feasibility examinations. In this seminar, progress and strategies in developing efficient photocatalysts for meaningful reactions (hydrogen production, H₂O₂ and etc) at larger-scale system will be shared.

Relevant recent works:

1. Solar Oxidative Hydrogen Peroxide Production: Is the Oxygen Vacancy Always a Promoter in Solar Water Oxidation? ACS Catalysis 2024, 14 (7), 5297-5304.
2. Clean Production of Hydrogen Peroxide: A Heterogeneous Solar-driven Redox Process, Adv. Energy Mater. 2023, 13 (36), 2301047.
3. Low-bias Photoelectrochemical Water Splitting via Mediating Trap States and Small Polaron Hopping, Nature Commun. 2022, 13 (1), 6231.

Biography

Yun Hau Ng is a Professor of Chemical Engineering at the Physical Science and Engineering (PSE) Division of the King Abdullah University of Science and Technology (KAUST). He received his PhD from Osaka University in 2009. Prior to his current position, he was a faculty member at UNSW Australia (2009-2018) and City University of Hong Kong (2018-2024). His research mainly focuses on the development of semiconductor-based photocatalysts and photoelectrochemical systems for sunlight energy conversion, including hydrogen generation from water, conversion of carbon dioxide to solar fuels, and ammonia synthesis. He received a few recognitions in photocatalysis research, including Honda-Fujishima Prize (2013), Distinguished Lectureship Award from the Chemical Society of Japan (2018), APEC Science Prize for Innovation, Research and Education (ASPIRE) in Chile (2019), and Kataoka Lectureship Award from the Japanese Photochemistry Association (2021). He is currently serving as an associate editor for Sustainable Materials and Technologies and Journal of Photochemistry & Photobiology A: Chemistry.