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[Display omitted] • Smartly designed metal/oxides heterojunction via a facile Ar-H 2 plasma reduction strategy. • The in-situ synthesized Ir/IrO 2 heterointerface possesses structural flexibility and abundant active sites. • Ir–IrO 2 /Ti@Ar–H 2 exhibits outstanding electrocatalytic activity and durability for both HER and OER. • Ir–IrO 2 /Ti@Ar–H 2 can used as an efficient and stable bifunctional catalyst for overall water splitting in acidic media. Iridium oxide (IrO 2) has been intensively investigated as an efficient and stable anode catalyst for the oxygen evolution reaction (OER) in water splitting system. However, the overall water splitting performance of IrO 2 is rarely studied because of its strong adsorption of hydrogen intermediates during the hydrogen evolution reaction (HER) process. Herein, a facile Ar/H 2 plasma reduction strategy is developed to activate the HER performance of self-supported IrO 2 by constructing a novel metal/oxide heterostructure. The in-situ synthesized Ir/IrO 2 composite possesses excellent electrical interconnection and abundant catalytic active sites. Meanwhile, dual active sites induced by the strong interface effect between metallic Ir and IrO 2 could optimize the adsorption energy and reaction path for both HER and OER. The optimized Ir–IrO 2 /Ti@Ar–H 2 exhibits remarkable activities with a small overpotential of 58 and 211 mV toward HER and OER, respectively. Besides, Ir–IrO 2 /Ti@Ar–H 2 ||Ir–IrO 2 /Ti@Ar–H 2 electrolyzer only requires an operational voltage of 1.48 V to afford a current density of 10 mA cm−2, much lower than that of commercial Pt/C||IrO 2 (1.61 V). [ABSTRACT FROM AUTHOR]

[Display omitted] • Devised a molecular dynamics/time-stamped force-bias Monte Carlo (MD/tfMC) simulation method. • Discovered a new FCC-Cu[110]//TiN[001] orientation relationship via UHV sputter deposition. • MD/tfMC simulations showed that Cu grows on TiN(001) initially as BCC-Cu[001]//TiN[001] • BCC-Cu transforms to nanotwinned FCC-Cu[110] via a Nishiyama-Wasserman type shear mechanism. • Investigated Cu growth on N- and Ti- terminated TiN(111) surfaces in detail via simulation. Using a sequential molecular dynamics (MD)/time-stamped force-bias Monte Carlo (tfMC) algorithm to simulate the deposition of Cu species onto a TiN(001) substrate at 600 K, it is shown for the first time that at the very early stage of growth, BCC-Cu grows pseudomorphically on the TiN(001) substrate as a very thin continuous film with the BCC-Cu[001]//TiN[001] growth direction. By increasing the thickness of the Cu thin film, however, the film transforms through the Nishiyama-Wasserman mechanism from BCC into predominantly FCC-Cu with abundant nanotwins, which is the same type of structure obtained in the experiment conducted here via a dc magnetron sputter deposition technique to grow Cu on TiN(001) at 105 °C. In agreement with the experimental observations in the literature, the devised MD/tfMC is employed further to reveal that on the N-terminated TiN(111), Cu shows a very poor wettability, and FCC-Cu(111) grows vertically in the form of tall 3D islands. On Ti-terminated TiN(111) surface, however, FCC-Cu(111) initially grows in the form of 2D islands with high wettability. With additional Cu deposition, a triangular misfit dislocation network is generated at the Cu(111)//Ti-terminated TiN(111) interface with subsequent formation of a two-layer nanotwin with its twinning plane parallel to the surface substrate. [ABSTRACT FROM AUTHOR]