A new transparent iridium oxide (IrO x ) film on fluorine-doped tin oxide (FTO) electrodes were achieved from a homogeneous precursor complex solution by employing a facile spin-coating technique. The composition of the nanostructure and crystallinity of the IrO x film is tunable by a simple annealing treatment of a compact complex layer, which is responsible for their significantly different electrocatalytic performances for water oxidation. Transmission electron microscopy (TEM) observations showed uniformly dispersed small IrO x nanoparticles of dimensions ca. 2–5 nm for the film annealed at 300 °C, and the nanoparticles gradually agglomerated to form relatively large particles at higher temperatures (400 and 500 °C). The IrO x films prepared at different annealing temperatures are characterized by Raman spectroscopic data to reveal intermediate IrO x (OH) y nanoparticles with two oxygen binding motifs: terminal hydroxo and bridging oxo at 300 and 350 °C annealing, via amorphous IrO x at 400 °C, transforming ultimately to crystalline IrO2 nanoparticles at 500 °C. Cyclic voltammetry suggests that the intrinsic activity of catalytic Ir sites in intermediate IrO x (OH) y nanoparticles formed at 300 °C annealing is higher in comparison with amorphous and crystalline IrO x nanoparticles. Electrochemical impedance data showed that the charge transfer resistance (R ct = 232 Ω) for the IrO x (OH) y film annealed at 300 °C is lower relative to that of films annealed at higher temperatures. This is ascribable to the facilitated electron transfer in grain boundaries between smaller IrO x particles to lead the efficient electron transport in the film. The high intrinsic activity of catalytic Ir sites and efficient electron transport are responsible for the high electrocatalytic performance observed for the intermediate IrO x (OH) y film annealed at 300 °C; it provides the lowest overpotential (η) of 0.24 V and Tafel slope of 42 mV dec–1 for water oxidation at neutral pH, which are comparable with values for amorphous IrO x ·nH2O nanoparticle films (40–50 mV dec–1) reported as some of the most efficient electrocatalysts so far.

Kleine Mesoporen sind effizienter: Ein mesoporöser Oxidhalbleiter (Wolfram(VI)‐oxid) wurde bei 550 °C unter Verwendung eines einfachen einstufigen Verfahrens kristallisiert. Das hochkristalline mesoporöse WO3 hat eine extrem große Oberfläche, die zu einer gesteigerten photoelektrochemische Aktivität bei der Wasseroxidation (siehe Bild) im Vergleich zu einem WO3‐Material mit Mesoporen zwischen den Partikeln führt.

New multifunctional luminescent hybrid mesoporous silicas (LHMS) containing a tunable chemosensor diimine moiety inside the pore wall have been synthesized. XRD and TEM image analyses indicate the formation of highly ordered 2D hexagonal mesophase from a 1:3 mixture of diimine organosilica and tetraethyl orthosilicate (TEOS) assisted by the supramolecular assembly of cetyltrimethylammonium bromide (CTAB); the use of diimine organosilica precursor alone leads to disordered mesophase. 13C CP MAS, 29Si MAS NMR, and UV−visible spectroscopic data show the incorporation of bridging organic diimine in the solid mesoporous materials. N2 sorption data suggest high BET surface areas together with type IV isotherms for the LHMS samples. These hybrid mesoporous materials show very strong affinity for metal cations (Fe3+, Zn2+, etc.), which could be utilized for possible application to metal ion chemosensors. All the LHMS samples exhibit very strong photoluminescence at room temperature and strong dependence of emission on exogenous ions. The highly ordered sample has the advantage over the disordered sample synthesized over pure diimine precursor, because its ion-exchange efficiency is high and it is synthesized with a small amount of diimine chemosensor precursor.

The creation of metal catalysts with highly active surfaces is pivotal to meeting the strong economic demand of the chemical industry.