For the growth of 2D transition metal dichalcogenides, such as molybdenum (MoS2) and tungsten disulfides (WS2), metalorganic chemical vapor deposition (MOCVD) routes are favorable due to their superior scalability, the possibility to tune the processing temperatures by a proper choice of reactants thus avoiding the need for a postdeposition treatment. Herein, the first example of a promising MOCVD route for the direct fabrication of MoS2 and WS2 layers under moderate process conditions is reported. This straightforward route is successfully realized by the combination of metalorganic precursors of Mo or W bearing the amidinato ligand with just elemental sulfur. The formation of stoichiometric hexagonal 2H‐MoS2 and 2H‐WS2 is demonstrated which is confirmed by Raman, X‐ray diffraction, and X‐ray photoelectron spectroscopy studies. The deposited layers are evaluated for their electrocatalytic activity in hydrogen evolution reaction as a proof of principle for application in water splitting devices.

In this paper, a direct chemical vapor deposition (CVD) approach is applied for the first time to synthesize high quality copper oxide (CuO), copper tungstate (CuWO4) and tungsten oxide (WO3) on F:SnO2 (FTO) substrates for photocatalytic water splitting.

Vapor phase deposited iron oxide nanostructures are promising for fabrication of solid state chemical sensors, photoelectrodes for solar water splitting, batteries, and logic devices. The deposition of iron oxide via chemical vapor deposition (CVD) or atomic layer deposition (ALD) under mild conditions necessitates a precursor that comprises good volatility, stability, and reactivity. Here, a versatile iron precursor, namely [bis(N‐isopropylketoiminate) iron(II)], which possesses ideal characteristics both for low‐temperature CVD and water‐assisted ALD processes, is reported. The films are thoroughly investigated toward phase, composition, and morphology. As‐deposited ALD grown Fe2O3 layers are amorphous, while the CVD process in the presence of oxygen leads to polycrystalline hematite layers. The nanostructured iron oxide grown via CVD consists of nanoplatelets that are appealing for photoelectrochemical applications. Preliminary tests of the photoelectrocatalytic activity of CVD‐grown Fe2O3 layers show photocurrent densities up to 0.3 mA cm−2 at 1.2 V versus reversible hydrogen electrode (RHE) and 1.2 mA cm−2 at 1.6 V versus RHE under simulated sunlight (1 sun). Surface modification by cobalt oxyhydroxide (Co‐Pi) co‐catalyst is found to have a highly beneficial effect on photocurrent, leading to maximum monochromatic quantum efficiencies of 10% at 400 nm and 4% at 500 nm at 1.5 V versus RHE.

Uniform and vertically aligned nanotube arrays of titanium oxynitride functionalized with iridium nanoparticles (Ir/TiON-NTs) were fabricated for the solar driven-water splitting.

Hybrid photoanodes comprising polymer-based light absorbers coupled to oxygen-evolving cocatalysts represent a promising, yes still underdeveloped, approach to photoelectrochemical splitting of water into hydrogen and oxygen. In this study, we investigate nickel oxide (NiO x ) nanoparticles as a water oxidation catalyst in hybrid photoanodes based on polymeric carbon nitride (CN x ) supported on electron-collecting mesoporous TiO2 support. The performance of the resulting TiO2–CN x /NiO x photoanodes is evaluated with respect to our previous results on hybrid TiO2–CN x photoanodes modified with IrO x and CoO(OH) x cocatalysts. The deposition of NiO x into TiO2–CN x photoanodes enhances significantly the photocurrent (from <8 μA to >250 μA cm–2 at 1.23 V vs. RHE) under visible light irradiation (λ > 420 nm, ∼200 mW cm−2) and triggers the photoelectrocatalytic oxygen evolution. No oxygen evolution was observed without a cocatalyst. As compared to photoanodes modified with IrO x or CoO(OH) x , the TiO2–CN x /NiO x photoanodes excel by the very negative photocurrent onset potential (0 V vs. RHE), which we ascribe to good hole-extracting properties of NiO x . However, the comparatively low Faradaic efficiencies for oxygen evolution (∼18%) and dramatically decreased operational stability of the photoanodes indicate that the extracted holes do not efficiently oxidize water to dioxygen, but instead accumulate in the NiO x particles and increase thus the oxidative photodegradation of the photoanodes. Our study highlights the fact that employing outstanding electrocatalysts like NiO x in photoelectrochemical water-splitting systems does not necessarily lead to satisfactory results, especially when the photoelectrode cannot be operated at optimal pH due to light absorber stability issues.