The utilization and development of efficient water electrolyzers for hydrogen production is currently limited due to the sluggish kinetics of the anodic processthe oxygen evolution reaction (OER). Moreover, state of the art OER catalysts contain high amounts of expensive and low-abundance noble metals such as Ru and Ir, limiting their large-scale industrial utilization. Therefore, the development of low-cost, highly active, and stable OER catalysts is a key requirement toward the implementation of a hydrogen-based economy. We have developed a synthetic approach to high-surface-area chlorine-free iridium oxide nanoparticles dispersed in titania (IrO2-TiO2), which is a highly active and stable OER catalyst in acidic media. IrO2-TiO2 was prepared in one step in molten NaNO3 (Adams fusion method) and consists of ca. 1–2 nm IrO2 particles distributed in a matrix of titania nanoparticles with an overall surface area of 245 m2 g–1. This material contains 40 molM % of iridium and demonstrates improved OER activity and stability in comparison to the commercial benchmark catalyst and state of the art high-surface-area IrO2. Ex situ characterization of the catalyst indicates the presence of iridium hydroxo surface species, which were previously associated with the high OER activity. Operando X-ray absorption studies demonstrate the evolution of the surface species as a function of the applied potential, suggesting the conversion of the initial hydroxo surface layer to the oxo-terminated surface via anodic oxidation (OER regime).

The Adams method is used to prepare IrO2–TiO2 materials, composed of nanoparticles, whose electrical conductivity follows percolation theory.

Herein, we report the preparation of small and narrowly distributed (2.1 ± 0.5 nm) Ag nanoparticles supported on passivated silica, where the surface OH groups are replaced by OSiMe3 functionalities. This synthetic method involves the grafting of silver(I) bis(trimethylsilyl)amide ([AgN(SiMe3)2]4) on silica partially dehydroxylated at 700 °C, followed by a thermal treatment of the grafted complex under H2. The catalytic performance of this material was investigated in the semi-hydrogenation of propyne and 1-hexyne and compared with that of 2.0 ± 0.3 nm Ag nanoparticles supported on silica. Whilst surface passivation slightly decreases the activity in both reactions (by a factor 2-3), probably as a result of the decreased alkyne adsorption properties or the presence of less accessible active sites on the passivated support, the AgNP@SiO2 catalysts demonstrate a remarkable selectivity for the production of alkenes.

The synthesis, characterisation and photocatalytic water splitting activity of blue tungsten oxide materials prepared from W(vi) and W(iv) precursors is reported.