CityU researcher wins distinguished materials science award

Monday Ng


Dr Xu Wanghuai
Dr Xu Wanghuai from the Department of Mechanical Engineering received the 2021 Materials Research Society (MRS) Graduate Student Award (Silver).  

Dr Xu Wanghuai, a recent PhD graduate in the Department of Mechanical Engineering, City University of Hong Kong (CityU), received the 2021 Materials Research Society (MRS) Graduate Student Award (Silver) for his pioneering research on the development of a novel droplet-based electricity generator for advancing scientific research into water energy generation. 

Dr Xu is the only recipient from Hong Kong as the other nine winners come from top 10 universities in US. In fact, only three researchers from Hong Kong have received this award since its inception in 2001, and they are all from CityU.

Through his research, titled “Fusion of Slippery Interfaces and Transistor-Inspired Architecture for Water Kinetic Energy Harvesting”, he has made breakthroughs in the design and development of the interface and architectural design of power generation devices. His work has enabled highly efficient harvesting of kinetic energy from water under a range of work conditions. As first author, Dr Xu has published several articles in top international journals such as Nature, Joule, and National Science Review.

With his novel method, the output performance of water harvesting can be enhanced in terms of voltage, current and electric power density when compared to existing methods for droplets. The open-circuit output voltage and short-circuit current were about 143.5 volts and 270.0 microamps, respectively—around 295 and 2,600 times higher than the values for more conventional designs. The instantaneous peak power density is 50.1 watts per square metre under a load resistance of 332.0 kiloohms, a thousand times higher than for similar devices.

DEG Paradigm shift
A schematic diagram displaying the advantages inherent in slippery interfaces and transistor-inspired architecture.

The electricity generated from one droplet could light up hundreds of LED bulbs. Moreover, the advantages inherent in slippery interfaces and transistor-inspired architecture allow efficient energy harvesting at many different scales under various conditions. His research has important application prospects in the fields of self-powered micro-nano devices, flexible electronics, intelligent life, green agriculture, and blue energy harvesting.


The water energy harvesting system applied to environmental monitoring device. 

His technology has been adopted by a project in collaboration with the Electrical and Mechanical Services Department, Hong Kong SAR Government. The aim is to save energy by harvesting the ubiquitous kinetic energy from water for environmental monitoring applications, such as humidity and temperature measurement. 

“It is of great scientific significance and application value to develop a kind of universal energy harvesting technology with high durability and high output performance. By harnessing the organic combination of manufacturing, fluid mechanics, interface science, materials, and energy, we have successfully achieved this objective,” said Dr Xu.

Chair Professor Wang Zuankai, Dr Xu’s supervisor in the Department of Mechanical Engineering, said the award reflected CityU's research excellence and global impact. 


“The field of energy research is of course extremely crowded, but Dr Xu has made remarkable achievements by translating his training, especially in multidisciplinary research, to address energy challenges facing us,” he said.

Dr Xu was also an awardee of the Research Grant Committee Postdoctoral Fellowship Scheme under the University Grants Committee this year in recognition of his outstanding research achievements.

The MRS promotes communication for the advancement of interdisciplinary materials research and technology to improve the quality of life. MRS Graduate Student Awards honour and encourage graduate students whose academic achievements and current materials research display a high level of excellence. 


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Communications and Institutional Research Office

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