Cost-effective catalyst for water-splitting devices
Although one of the best means of sourcing renewable energy, solar systems cannot consistently produce adequate energy since sunlight varies from time to time and place to place. A solution to this problem is a device that can store energy in the form of hydrogen for later use, offering a consistent output over time with very little pollution.
One of the most sustainable methods of producing hydrogen is photoelectrochemical (PEC) water-splitting. Solar energy is used to break water molecules into hydrogen and oxygen through a process called "hydrogen evolution reaction". This reaction requires a catalyst, which is a chemical agent that increases its speed. In PEC water-splitting devices, a common catalyst used to split water is platinum, which is deposited on the surface of the solar panel's photocathode – the solar panel's electrode that converts light into electric current.
A research team at EPFL has now found a way to make efficient solar-powered water splitting devices using abundant and cheap materials. The group of Xile Hu developed a molybdenum-sulfide catalyst for the hydrogen evolution reaction, and the group of Michael Grätzel developed copper(I) oxide as a photocathode. The researchers found that the molybdenum sulfide can be deposited on the copper(I) oxide photocathode for use in PEC water splitting through a simple deposition process that can be easily expanded onto a large scale.
The technique shows comparable efficiency to other hydrogen evolution reaction catalysts like platinum, it preserves the optical transparency for the light-harvesting surface and it shows improved stability under acidic conditions, which could translate into lower maintenance. But more importantly, both the catalyst and the photocathode are made with cheap, earth-abundant materials that could greatly reduce the cost of PEC water-splitting devices in the future. According to senior author Xile Hu, the work represents a state-of-the-art example for solar hydrogen production devices.
Original publication
Morales, Guio CG, David Tilley S, Vrubel H, Grätzel M, Hu X. Hydrogen evolution from a copper(I) oxide photocathode coated with an amorphous molybdenum sulphide catalyst. Nature Communications, 8 January 2014
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Original publication
Morales, Guio CG, David Tilley S, Vrubel H, Grätzel M, Hu X. Hydrogen evolution from a copper(I) oxide photocathode coated with an amorphous molybdenum sulphide catalyst. Nature Communications, 8 January 2014
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