Engineers at UNSW Sydney have revolutionized the traditional silicon solar panel, transforming it into a device capable of producing ammonia in a much more environmentally friendly way. Ammonia plays a crucial role in manufacturing fertilizers that support global agriculture and food production. However, conventional methods of ammonia production are notorious for their significant greenhouse gas emissions, as they rely heavily on fossil fuels for hydrogen production and the high-energy processes involved.
In a groundbreaking development, UNSW Scientia Professor Rose Amal, in collaboration with Professor Xiaojing Hao and their teams, has pioneered a method to generate ammonium ions from nitrate-containing wastewater. This innovation is powered solely by a specially designed solar panel that mimics the function of an artificial leaf.
Their research, recently published in the Journal of Energy and Environmental Science, introduces a process known as photoelectrocatalysis (PEC). This method employs a nano-structured thin layer of copper and cobalt hydroxide on the solar panel, which acts as a catalyst to facilitate the chemical reaction necessary to produce ammonium nitrate from wastewater.
The team, including lead author Chen Han and Dr. Jian Pan, a DECRA Fellow, has successfully built a 40cm² artificial leaf system on the roof of the Tyree Energy Technologies Building at UNSW. This system has demonstrated the capability to produce ammonium ions sufficient to fertilize 1.49m² of cropland. The promising results pave the way for scaling up the system, potentially enabling ammonia production without the associated greenhouse gas emissions.
“Traditional ammonia production requires high temperatures—around 400 to 500 degrees Celsius—and high pressure, historically necessitating the use of fossil fuels,” explained Professor Amal from the School of Chemical Engineering. “Our system operates under ambient conditions, using only sunlight to produce ammonium from nitrate-containing wastewater, a key ingredient in fertilizers. We believe this new technology could be deployed on a relatively small scale in agricultural settings to produce ammonium onsite, decentralizing the production process and further reducing CO2 emissions related to transportation.”
This innovative process draws inspiration from nature. In real leaves, photosynthesis allows plants to convert sunlight, water, and carbon dioxide into oxygen and sugar. Similarly, this new photoelectrocatalytic process enables the solar panel to function as an artificial leaf, utilizing sunlight and nitrate-containing wastewater to produce ammonium nitrate.
Lead author Chen Han emphasized the interdisciplinary collaboration behind the breakthrough: “We are combining photovoltaics expertise from UNSW’s School of Photovoltaics & Renewable Energy Engineering with our chemical engineering know-how to transform nitrate waste into a valuable commodity—ammonia. We’ve developed an efficient catalyst with unique nanostructures and integrated it with a traditional silicon solar panel, resulting in a highly effective process.”
The findings offer a clean, efficient, and cost-effective solution for harnessing solar energy and chemical waste to produce ammonia and other valuable products. While the current system produces ammonia in concentrations suitable for fertilizer, the researchers acknowledge there is still room for improvement.
Looking ahead, the team hopes that the processed wastewater, once converted to ammonium, can be repurposed for crop irrigation, further enhancing agricultural productivity. “It’s important to note that the wastewater we convert isn’t directly sourced from municipal waste or runoff—it must first be treated to remove organic matter and particulates,” said Professor Amal. “However, we’re optimistic that the treated water, after ammonium generation, can be used for irrigation.”
Professor Amal is eager to explore further collaborations with industry partners to advance this innovative process into a fully viable commercial system.
By Impact Lab
