• Universitat de València
• Universitat Jaume I

• Pedro Javier Rodríguez Cantó
• Sixto Giménez Julia
• Miguel García Tecedor

Nowadays, there is a growing need for clean and renewable energy generation to combat climate change. The use of H2 as a fuel for electricity generation is one of the most promising solutions in terms of sustainability, as it is completely clean and has H2O as the only reaction product. This process takes place in a fuel cell. The hydrolysis of water is a process that is only spontaneous at very high temperatures, around 2200ºC. To carry out the reaction at room temperature, a large amount of extra energy is required compared to what is theoretically necessary to carry out the reaction (+1.23V). This is because, as in any chemical reaction, the activation energy of the reaction must be exceeded for the reaction to occur. Catalysts are used to reduce the energy required.

Although the use of photoelectrochemistry in hydrogen production has enormous potential, it has not yet been possible to develop an application that can compete economically with conventional processes. Currently, the best performing electrocatalytic systems are based on the use of precious metals (RuO2, IrO2, or Pt), which are highly expensive. Methane reforming, on the other hand, allows hydrogen to be obtained cheaply (€3/kg), but with a significant carbon footprint that must be eliminated. There is therefore a need to develop new catalysts based on metals that are more abundant in the earth's crust.

Researchers from the Universitat de València, the Universitat Jaume I and Intenanomat S.L. have collaboratively developed a novel material based on non-stoichiometric nickel oxide (NiOx) that shows excellent electrocatalytic properties for the electrolysis (oxidation) of water, even improving the efficiency of electrocatalysts based on precious metals (RuO2, IrO2, or Pt). The technology allows the synthesis of the electrocatalyst by formulating various NiOx precursors in solution for deposition on different types of substrates in a single step using different printing techniques. The resulting material has excellent electrocatalytic properties for water oxidation with low energy requirements. The manufacturing method used is also fully scalable and compatible with continuous roll-to-roll manufacturing techniques, where flexible substrates or thin metal foils are required.

The invention would be applicable in electrocatalysts for electrochlorination and water purification and in fuel cells for electricity generation from H2 and O2. It can also be used in the formulation of coatings and paints with photocatalytic properties and in materials for hole-selective transport layers for photovoltaics and optoelectronics, such as LEDs.

The proposed system has clear advantages over existing systems:

• High performance: low energy requirement and high stability.
• Low raw material cost. The electrocatalyst consists mainly of nickel, one of the most abundant chemical elements (approx. 17 €/kg).
• Low manufacturing cost. Manufacture by continuous industrial methods such as roll-to-roll or digital ink-jet printing.
• Versatility: wide range of applications in electrochemistry, not only as an electrocatalyst for water electrolysis but also for reactions such as electrochlorination of water from brine for drinking water purification.
• Operating cost reduction of 20-35% in electrochemical processes.

• Patent granted