Metal nanoparticles (NPs) can act as catalysts for a variety of reactions. Combining a metal with other elements in NPs can be used to develop new and improved catalysts. Usually, the second element is also a metal and the result is a nanoalloy catalyst. Non-metal alternatives, e.g., in metal phosphide NPs, have been less well explored.

Takato Mitsudome, Osaka University, Japan, and colleagues have found that nickel phosphide nanoparticles (Ni₂P NPs) can be used as highly active and selective catalysts for the transformation of 5-(hydroxymethyl)furfural (HMF) derivatives to 2,5-diketones in water. This reaction is useful in biorefinery processes that can transform sustainably sourced sugars into useful chemical building blocks. The team prepared the nanoparticles by adding NiCl₂, hexadecylamine, and triphenylphosphite to 1-octadecene and heating the reaction mixture up to 300 °C.

The resulting Ni₂P NPs were used as catalysts for the hydrogenation of 5-methylfurfural under H₂ in water. The diketone 2,5-hexanedione was obtained in a yield of 38 %. According to the researchers, this is the first example of this direct reaction with a nonprecious metal catalyst. The yield was improved to 74 % by dispersing the Ni₂P NPs on a zeolite support. The catalyst can be recovered and reused.

• Unique Catalysis of Nickel Phosphide Nanoparticles to Promote the Selective Transformation of Biofuranic Aldehydes into Diketones in Water,
  Shu Fujita, Kiyotaka Nakajima, Jun Yamasaki, Tomoo Mizugaki, Koichiro Jitsukawa, Takato Mitsudome,
  ACS Catalysis 2020.
  https://doi.org/10.1021/acscatal.9b05120