Solar-Powered Water Purification: Guihua Yu’s Hydrogel Innovations

Breaking the Wall of Solar Water Sustainability

Winner Interview 2024: Engineering & Technology

Guihua Yu has developed innovative hydrogel-based solar evaporators and atmospheric water harvesters. His research offers efficient, affordable solutions for clean water production using renewable solar energy, addressing water scarcity and promoting sustainable resource management.

Which wall does your research or project break?

Energy and water are of fundamental importance to our modern society, and advanced technologies on sustainable energy storage and conversion as well as water resource management are in the focus of intensive research worldwide. One of the grand challenges is how to effectively utilize renewable solar energy to provide sustainable solutions to clean water production.

Solar vapor generation is a promising technology to upgrade water quality from seawater or wastewater via solar powered evaporation, however, one critical challenge of solar-driven evaporation is that diffusive solar energy cannot meet the high energy barrier needed for evaporation of water, often requiring complex yet costly optical accessories to power efficient water evaporation process. We have pioneered a novel class of hydrogels with tunable water-polymer interactions that can achieve record-high evaporation rates under natural sunlight. A series of our works on hydrogels-based solar evaporators have triggered worldwide interests in this growing field of solar water purification and desalination with new perspective of tuning water-material interaction compared with traditional approaches of changing solar absorptive materials. These novel hydrogel-based solar evaporator materials have substantial impacts on fundamental water research, purification technologies, and environmental conservation.

Atmosphere water harvesting is considered another critical alternative technology for clean water production as atmospheric water reservoir contains ~13 trillion tons of fresh water. We have developed effective yet sustainable solutions based on novel hybrid hydrogels materials to achieve record-performance solar-powered water harvesting from the ambient air. Compared with traditional hygroscopic materials such as zeolites or silica materials, we developed the first-of-its-kind solar-powered super-moisture adsorbent gels (SMAGs)-based atmospheric water harvesting with record-high water collection efficiency, by introducing the new concept of thermoresponsive polymers to enable the most energy-efficient water release. We then invented the first all-biomass-derived cost-effective super hygroscopic polymer films based solar-powered atmospheric water harvesters, marking a significant step towards practical technology.

What are the three main goals of your research or project?

1. Further scientific understanding of fundamental processes and chemical/molecular interactions involved in many solar-water technologies.

One of the grand challenges in the field is how to effectively utilize renewable solar energy to provide sustainable solution to clean water production. Solar-powered water evaporation provides the basis for the development of eco-friendly and cost-effective freshwater production. The very key is to understand fundamental principles of materials design for efficient solar-to-thermal energy conversion and vapor generation, which involve photothermal materials, various nanostructures/microstructures and water–material interactions to greatly improve the performance of the evaporation system towards practical water-purification applications. Similarly, atmospheric water harvesting is another promising technology to address the global challenge of water scarcity by tapping into the vast reserves of atmospheric moisture for potable water supply. Understanding fundamental processes in two key steps involving water sorption and water release Is crucial for materials innovation to enable highly efficient water extraction from ambient air to promote AWH technology for decentralized water supply.

2. Translate scientific discoveries and materials innovation to enable technological advancement in sustainable energy-water nexus.

Compared with current water-purification and water-harvesting technologies that consume considerable energy, solar-driven water-purification and water-harvesting technologies are very promising. As renewable solar energy is the only energy input for water evaporation or atmospheric water harvesting, avoiding dependence on electricity and complex infrastructure. With many exciting material innovations, especially newly developed hydrogels, we aim to bring them beyond laboratory research towards practical energy-efficient yet low-cost solar evaporation systems for water purification (can even for seawater desalination) and/or atmospheric water generators, for many household applications, especially in many water-stressed areas as well as for emergency use, such as in disaster relief.

3. Work with society and world organizations to promote sustainable energy-water technology.

At the forefront of the United Nation’s Sustainable Development Goals (SDGs), particularly SDG6 (i.e., universal and equitable access to safe and affordable drinking water for all) and SDG7 (i.e., affordable and clean energy for all), renewable solar-driven water technologies can be particularly promising for promoting innovative solutions to produce clean drinking water to off-grid communities, especially under economic-challenging conditions as well as in arid regions, remote regions. We also aim to work with many societies and world organizations to promote these cost-effective and renewable energy powered sustainable solutions, especially to meet the needs of the developing communities lacking access to the most basic of human needs, clean drinking water.

What advice would you give to young scientists or students interested in pursuing a career in research, or to your younger self starting in science?

I always believe the biggest problem that scientists face is how we can provide timely and effective solutions for grand global challenges such as climate change, sustainable energy, and water crisis.

For young scientists or students, the first is to choose an important scientific topic of immense societal impacts, the second is always working hard to achieve and never giving up on your dreams.

Sharing my favorite quote “Genius is one percent inspiration and ninety-nine percent perspiration.” (Thomas Edison)

What inspired you to be in the profession you are today?

My greatest achievement has been becoming a science and engineering professor who has the privilege to work with thousands of young minds to pursue their dreams in science and technology beneficial to society.