Transition metal dichalcogenide materials have been explored extensively as catalysts to negotiate the hydrogen evolution reaction, but they often run at a large excess thermodynamic cost. Although activating strategies, such as defects and composition engineering, have led to remarkable activity gains, there remains the requirement for better performance that aims for real device applications. We report here a phosphorus-doping-induced phase transition from cubic to orthorhombic phases in CoSe2. It has been found that the achieved orthorhombic CoSe2 with appropriate phosphorus dopant (8 wt%) needs the lowest overpotential of 104 mV at 10 mA cm−2 in 1 M KOH, with onset potential as small as −31 mV. This catalyst demonstrates negligible activity decay after 20 h of operation. The striking catalysis performance can be attributed to the favorable electronic structure and local coordination environment created by this doping-induced structural phase transition strategy.

The growth and interfacial electronic properties of Ag on CeO 2 (111) thin films have been studied by synchrotron radiation photoemission spectroscopy (SRPES), low energy electron diffraction (LEED), and X-ray photoelectron spectroscopy (XPS). Stoichiometric CeO 2 (111) thin films were grown on a Ru(0001) substrate. Ag grows as three-dimensional (3D) particles on the well-ordered CeO 2 (111) surface at 300 K with a number density of ∼1 Â 10 12 particles/cm 2 . When the CeO 2 (111) surface has a high density of defects, Ag initially populates these defect sites, leading to a two-dimensional (2D) island growth at low coverages followed by 3D islanding at high coverages. The binding energy of Ag 3d increases when the Ag particle size decreases, which is mainly attributed to the final-state screening. No strong interaction between Ag and CeO 2 (111) is found. The CeO 2 (111) surface is slightly reduced upon Ag deposition, which can be ascribed to the reverse spillover of oxygen atoms from the Ag-CeO 2 boundary to the Ag nanoparticles. The Ag particles on CeO 2 (111) experience significant sintering when the temperature increases before they desorb from the surface.

In situ metalation of tetraphenylporphyrin (2HTPP) (sub)monolayers with Ni on a TiO2(110) surface to nickel(II)-tetraphenylporphyrin (NiTPP) depends on temperature and order of deposition, and affects conformation and bonding geometry of the porphyrin.