The crystal structures of double-decker single molecule magnets (SMM) LnPc(2) (Ln = Tb(III) and Dy(III); Pc = phthalocyanine) and non-SMM YPc(2) were determined by using X-ray diffraction analysis. The compounds are isomorphous to each other. The compounds have metal centers (M = Tb(3+), Dy(3+), and Y(3+)) sandwiched by two Pc ligands via eight isoindole-nitrogen atoms in a square-antiprism fashion. The twist angle between the two Pc ligands is 41.4 degrees. Scanning tunneling microscopy was used to investigate the compounds adsorbed on a Au(111) surface, deposited by using the thermal evaporation in ultrahigh vacuum. Both MPc(2) with eight lobes and MPc with four lobes, which has lost one Pc ligand, were observed. In the scanning tunneling spectroscopy images of TbPc molecules at 4.8 K, a Kondo peak with a Kondo temperature (T(K)) of approximately 250 K was observed near the Fermi level (V = 0 V). On the other hand, DyPc, YPc, and MPc(2) exhibited no Kondo peak. To understand the observed Kondo effect, the energy splitting of sublevels in a crystal field should be taken into consideration. As the next step in our studies on the SMM/Kondo effect in Tb-Pc derivatives, we investigated the electronic transport properties of Ln-Pc molecules as the active layer in top- and bottom-contact thin-film organic field effect transistor devices. Tb-Pc molecule devices exhibit p-type semiconducting properties with a hole mobility (mu(H)) of approximately 10(-4) cm(2) V(-1) s(-1). Interestingly, the Dy-Pc based devices exhibited ambipolar semiconducting properties with an electron mobility (mu(e)) of approximately 10(-5) and a mu(H) of approximately 10(-4) cm(2) V(-1) s(-1). This behavior has important implications for the electronic structure of the molecules.

Single-atom electrocatalysts (SAEs) can realize the target of low-cost by maximum atomic efficiency. However, they usually suffer performance decay due to high energy states, especially in a harsh acidic water splitting environment. Here, we conceive and realize a double protecting strategy that ensures robust acidic water splitting on Ir SAEs by dispersing Ir atoms in/onto Fe nanoparticles and embedding IrFe nanoparticles into nitrogen-doped carbon nanotubes (Ir-SA@Fe@NCNT). When Ir-SA@Fe@NCNT acts as a bifunctional electrocatalyst at ultralow Ir loading of 1.14 μg cm −2 , the required overpotentials to deliver 10 mA cm −2 are 250 and 26 mV for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in 0.5 M H 2 SO 4 electrolyte corresponding to 1370-and 61-fold better mass activities than benchmark IrO 2 and Pt/C at an overpotential of 270 mV, respectively, resulting in only 1.51 V to drive overall water splitting. Moreover, remarkable stability is also observed compared to Pt/ C-IrO 2 .

Simultaneous improvements in oxygen reduction reaction (ORR) activity and long-term durability of Ptbased cathode catalysts are indispensable for the development of next-generation polymer electrolyte fuel cells but are still a major dilemma. We present a robust octahedral core−shell PtNi x /C electrocatalyst with high ORR performance (mass activity and surface specific activity 6.8−16.9 and 20.3−24.0 times larger than those of Pt/C, respectively) and durability (negligible loss after 10000 accelerated durability test (ADT) cycles). The key factors of the robust octahedral nanostructure (core−shell Pt 73 Ni 27 /C) responsible for the remarkable activity and durability were found to be three continuous Pt skin layers with 2.0−3.6% compressive strain, concave facet arrangements (concave defects and high coordination), a symmetric Pt/Ni distribution, and a Pt 67 Ni 33 intermetallic core, as found by STEM-EDS, in situ XAFS, XPS, etc. The robust core−shell Pt 73 Ni 27 /C was produced by the partial release of the stress, Pt/Ni rearrangement, and dimension reduction of an as-synthesized octahedral Pt 50 Ni 50 /C with 3.6−6.7% compressive Pt skin layers by Ni leaching during the activation process. The present results on the tailored synthesis of the PtNi x structure and composition and the better control of the robust catalytic architecture renew the current knowledge and viewpoint for instability of octahedral PtNi x /C samples to provide a new insight into the development of next-generation PEFC cathode catalysts. KEYWORDS: robust octahedral core−shell PtNi x /C electrocatalyst, polymer electrolyte fuel cell, high performance and durability, continuous, compressive and concave Pt skin layers, structural and electronic property, in situ XAFS/STEM-EDS/XPS/ICP-AES