We describe the direct preparation of crystalline NiS thin films via atomic layer deposition (ALD) techniques at temperatures as low as 250 °C without postthermal treatments. A new ALD chemistry is proposed using bis(1-dimethylamino-2-methyl-2-butoxy) nickel(II) [Ni(dmamb)] and HS as precursors. Homogeneous and conformal depositions of NiS films were achieved on 4 in. wafers (both metal and oxide substrates, including Au and SiO). The resulting crystalline NiS layers exhibited highly efficient and stable performance as electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline solutions, with a low overpotential of 300 mV and a high turnover frequency for HER and an overpotential of 400 mV for OER (at a current density of 10 mA/cm). Using our NiS films as both the cathode and the anode, two-electrode full-cell electrolyzers were constructed, which showed stable operation for 100 h at a current density of 10 mA/cm. The proposed ALD electrocatalysts on planar surfaces exhibited the best performance among NiS materials for overall water splitting recorded to date.

The authors describe the atomic layer deposition (ALD) of titanium oxysulfide films (TiO2−xSx). A new ALD chemistry of tetrakis(dimethylamido)titanium and hydrogen sulfide is proposed for fabricating amorphous titanium sulfide layers. They found that the resulting films subsequently underwent oxidation upon reactions under the ambient condition, resulting in TiO2−xSx. The resultant structures were analyzed by using x-ray diffraction, transmission electron microscopy, and x-ray photoelectron spectroscopy, indicative of the formation of TiO2−xSx. A combined study of Hall effect measurements and Mott–Schottky analysis showed n-type semiconductor behaviors possessing a good conductivity. Optical properties testify that the present system has a moderate bandgap in between the related binary end compounds such as TiS2 and TiO2.

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Hematite (α‐Fe2O3) has attracted considerable attention as an anode material due to its high theoretical capacity (1,007 mAhg−1), low cost, and non‐toxicity. The conversion reaction, which often leads to the pulverization of hematite and degradation of electrochemical performances (e. g., capacity retention, high rate capability), is also found in hematite as Fe2O3 + 6Li+ + 6e– → 2Fe + Li2O. Here, we synthesized nanotubular hetero‐structures using α‐Fe2O3 and TiN via atomic layer deposition (ALD) without any binders. The initial reversible charge capacity of Fe2O3@TiN nanotubes (NTs) was 952 mAhg−1 with a retention of 673 mAhg−1 after 30 cycles. Porous Fe2O3 NTs with conductive TiN NTs exhibited enhanced electrochemical performances when used as an anode material.