Storing solar energy: Novel catalyst for water splitting

Water splitting requires carefully designed, durable catalysts. An international team of scientists, led by Mohamed Alkordi at Egypt’s Zewail City of Science and Technology, has developed a new method for generating hybrid nanoparticle/graphene catalysts based on microporous metal–organic frameworks (MOFs).

MOFs are synthetic compounds consisting of clusters of metal ions connected by organic ligands. By subjecting MOFs to extreme heat, their chemical structure can be altered to create metal-based nanoparticles for use as catalysts. The novel ‘one-pot’ approach taken by Alkordi’s team removes the need for this energy-intensive transformation, and uses the abundant, low cost material graphene as the composite base. 

The researchers deposited a microporous, zirconium-based MOF onto ultrathin graphene sheets, before adding nickel ions to the composite. They then immersed the composite in alkaline solution and passed an electric current through it, triggering a chemical reaction to restructure the composite into nickel hydroxide nanoparticles deposited on the graphene base. These nanoparticles have proven to be exceptionally active catalysts for water splitting.  

“This enhanced catalytic activity and durability are consequences of our optimized composition, namely the active nickel ions, the MOF host, and the electronically conductive graphene support,” says Alkordi. 

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